Chondrichthyes

Abstract In this paper are recorded the results of an investigation undertaken at the instance of Dr. A. Smith Woodward for the purpose of ascertaining to what extent the pattern presented by the calcified laminæ of the centrum is of value as an aid to the classification of Elasmobranch fishes, and to the identification of vertebræ found in the fossil state. The subject was dealt with exhaustively in 1879-1885 by Hasse, who, in his monograph ‘Das natürliche System der Elasmobranchier,’ claimed that the differences in the disposition of the calcified laminæ in the various genera and families of Elasmobranchs occur with such constancy and regularity that they may be accepted with confidence as an important factor in taxonomy. During the years, however, that have passed since the publication of this monograph the thesis has come to be looked upon with suspicion, and vertebrate morphologists at the present time do not, as a whole, regard Hasse’s definitions of the Cyclospondyli, Tectospondyli, and Asterospondyli as consistently applicable to the genera and species included by him within those groups. The material studied in the course of the investigation was to a large extent accumulated several years ago (see p. 313), and it was only the superior attraction of Cephalodiscus as a subject of research that prevented the work from being brought to an earlier conclusion. The examination of this accumulated material, and of that more recently acquired, was carried on in the Huxley Research Laboratory of the Imperial College of Science during the winter of 1917 and from May, 1919, to May, 1920, and I hereby acknowledge my great indebtedness to Prof. E. W. MacBride and the administrative officers of the College for the facilities offered there for the prosecution of the work. I have further to thank Prof. MacBride for frequent advice and for valuable suggestions made during the progress of the research. My thanks are also due, and are hereby tendered, to Dr. A. Smith Woodward and Mr. C. Tate Began, of the British Museum (Natural History), for many helpful hints and suggestions. Acknowledgments and thanks for material kindly furnished by various donors are recorded on p. 313.

@article{doi101098rstb19210008,
    author = "Ridewood, W. G. and MacBride, E. W.",
    title = "VIII.—On the calcification of the vertebral centra in sharks and rays",
    year = "1921",
    journal = "Philosophical Transactions of the Royal Society of London Series B Containing Papers of a Biological Character",
    abstract = "Abstract In this paper are recorded the results of an investigation undertaken at the instance of Dr. A. Smith Woodward for the purpose of ascertaining to what extent the pattern presented by the calcified laminæ of the centrum is of value as an aid to the classification of Elasmobranch fishes, and to the identification of vertebræ found in the fossil state. The subject was dealt with exhaustively in 1879-1885 by Hasse, who, in his monograph ‘Das natürliche System der Elasmobranchier,’ claimed that the differences in the disposition of the calcified laminæ in the various genera and families of Elasmobranchs occur with such constancy and regularity that they may be accepted with confidence as an important factor in taxonomy. During the years, however, that have passed since the publication of this monograph the thesis has come to be looked upon with suspicion, and vertebrate morphologists at the present time do not, as a whole, regard Hasse’s definitions of the Cyclospondyli, Tectospondyli, and Asterospondyli as consistently applicable to the genera and species included by him within those groups. The material studied in the course of the investigation was to a large extent accumulated several years ago (see p. 313), and it was only the superior attraction of Cephalodiscus as a subject of research that prevented the work from being brought to an earlier conclusion. The examination of this accumulated material, and of that more recently acquired, was carried on in the Huxley Research Laboratory of the Imperial College of Science during the winter of 1917 and from May, 1919, to May, 1920, and I hereby acknowledge my great indebtedness to Prof. E. W. MacBride and the administrative officers of the College for the facilities offered there for the prosecution of the work. I have further to thank Prof. MacBride for frequent advice and for valuable suggestions made during the progress of the research. My thanks are also due, and are hereby tendered, to Dr. A. Smith Woodward and Mr. C. Tate Began, of the British Museum (Natural History), for many helpful hints and suggestions. Acknowledgments and thanks for material kindly furnished by various donors are recorded on p. 313.",
    url = "https://doi.org/10.1098/rstb.1921.0008",
    doi = "10.1098/rstb.1921.0008",
    openalex = "W2156728886"
}

The maximum yield of the school shark fishery in south-eastern Australian waters was 4.09 million lb in 1949. The catch has fluctuated since then about a declining trend to 3.18 million lb in 1956. In 1944, 7.3 hooks were required to catch a shark of mean weight 14.7 lb. In 1956 the number of hooks required was almost doubled: 13.6 hooks were needed to catch sharks of mean weight 13.7 lb; the catch per hook dropped from 2.01 to 0.99 lb. Whereas the catch per boat-month remained relatively stable at 4765 lb for 1944 and 4643 for 1956, the number of hooks used per boat-month increased from 2366 to 4668 hooks in 12 years. Throughout this period the mean weight of sharks in eastern Bass Strait remained fairly steady (11-13 lb) whereas there was a drop of 3 lb from a mean weight of 17-20 lb in the predominantly mature portion of the stock in western Bass Strait. Fishermen in South Australia have reported a comparable drop in the mean weight of sharks in their catches. During the period 1941-46 there was unrestricted inshore fishing of juveniles and pregnant females with a consequent severe drop in the inshore population. The subsequent decline in the annual total catch is believed to be due not only to a too intensive offshore fishery but also to the resultant reduced recruitment and depressed reproductive potential caused by the earlier destruction of juveniles and pregnant females. In the data presented in this paper there is evidence that the school shark fishery, which is operating on a single stock of sharks with a slow growth rate, a late sexual maturity, and a low fecundity, shows trends which are suggestive of depletion. Because similar trends in the soupfin shark fishery of California and in the dogfish fishery of British Columbia were followed by depletion, it has been inferred that regulations to protect the vulnerable phases of the life history of the school shark of Australia may be required. Measures for conservation are discussed.

@article{doi101071mf9590150,
    author = "Olsen, AM",
    title = "The Status of the School Shark Fishery in South-Eastern Australian Waters",
    year = "1959",
    journal = "Marine and Freshwater Research",
    abstract = "The maximum yield of the school shark fishery in south-eastern Australian waters was 4.09 million lb in 1949. The catch has fluctuated since then about a declining trend to 3.18 million lb in 1956. In 1944, 7.3 hooks were required to catch a shark of mean weight 14.7 lb. In 1956 the number of hooks required was almost doubled: 13.6 hooks were needed to catch sharks of mean weight 13.7 lb; the catch per hook dropped from 2.01 to 0.99 lb. Whereas the catch per boat-month remained relatively stable at 4765 lb for 1944 and 4643 for 1956, the number of hooks used per boat-month increased from 2366 to 4668 hooks in 12 years. Throughout this period the mean weight of sharks in eastern Bass Strait remained fairly steady (11-13 lb) whereas there was a drop of 3 lb from a mean weight of 17-20 lb in the predominantly mature portion of the stock in western Bass Strait. Fishermen in South Australia have reported a comparable drop in the mean weight of sharks in their catches. During the period 1941-46 there was unrestricted inshore fishing of juveniles and pregnant females with a consequent severe drop in the inshore population. The subsequent decline in the annual total catch is believed to be due not only to a too intensive offshore fishery but also to the resultant reduced recruitment and depressed reproductive potential caused by the earlier destruction of juveniles and pregnant females. In the data presented in this paper there is evidence that the school shark fishery, which is operating on a single stock of sharks with a slow growth rate, a late sexual maturity, and a low fecundity, shows trends which are suggestive of depletion. Because similar trends in the soupfin shark fishery of California and in the dogfish fishery of British Columbia were followed by depletion, it has been inferred that regulations to protect the vulnerable phases of the life history of the school shark of Australia may be required. Measures for conservation are discussed.",
    url = "https://doi.org/10.1071/mf9590150",
    doi = "10.1071/mf9590150",
    openalex = "W2002649917"
}

The Shark Research Panel Get access Perry W. Gilbert Perry W. Gilbert Department of Zoology, Cornell University, Ithaca, New York Search for other works by this author on: Oxford Academic Google Scholar AIBS Bulletin, Volume 10, Issue 1, February 1960, Pages 19–20, https://doi.org/10.2307/1292691 Published: 01 February 1960

@article{doi1023071292691,
    author = "Gilbert, Perry W.",
    title = "The Shark Research Panel",
    year = "1960",
    journal = "AIBS Bulletin",
    abstract = "The Shark Research Panel Get access Perry W. Gilbert Perry W. Gilbert Department of Zoology, Cornell University, Ithaca, New York Search for other works by this author on: Oxford Academic Google Scholar AIBS Bulletin, Volume 10, Issue 1, February 1960, Pages 19–20, https://doi.org/10.2307/1292691 Published: 01 February 1960",
    url = "https://doi.org/10.2307/1292691",
    doi = "10.2307/1292691",
    openalex = "W2326913536"
}

@article{denton1964the2,
    author = "Denton, E. J. and Nicol, J. A. C",
    title = "The chorioidal tapeta of some cartilaginous fishes (Chondrichthyes)",
    year = "1964",
    journal = "Journal of the Marine Biological Association of the United Kingdom, v. 44, p. 219-258",
    note = "talkorigins\_source = {true}; raw\_reference = {Denton, E. J., and Nicol, J. A. C., 1964, The chorioidal tapeta of some cartilaginous fishes (Chondrichthyes): Journal of the Marine Biological Association of the United Kingdom, v. 44, p. 219-258.}"
}

@book{gilbert1967sharks4,
    author = "Gilbert, P. W. and Mathewson, R. F. and Rall, D. P",
    title = "Sharks, Skates and Rays",
    year = "1967",
    publisher = "Baltimore, Md., The Johns Hopkins Press",
    note = "talkorigins\_source = {true}; raw\_reference = {Gilbert, P. W., Mathewson, R. F., and Rall, D. P., 1967, Sharks, Skates and Rays: Baltimore, Md., The Johns Hopkins Press.}"
}

The morphology of thefeedingapparatus in several genera of carcharhinid sharks (Carcharhinus, Rhizoprionodon, Hypoprion, Prionace, Galeocerdo and Negaprion) was studied in both fresh and preserved states. The actions of the cranial musculature were determined through electrical stimulation. The feeding behaviours of representatives of the genera Carcharhinus, Negaprion and Galeocerdo were studied under controlled conditions by direct observation as well as photographically. The cranial anatomy of carcharhinid sharks is characterized by a relatively reduced chondrocranium and a greatly hypertrophied musculature. The hyostylic jaw suspension serves to allow substantial cranial kinesis, particularly with respect to the upper jaw. Protraction of this skeletal element is accomplished in at least two ways, depending on the external and internal forces applied to the palatoquadrate cartilage. Under one set of conditions upper jaw protraction serves to allow precision when feeding on benthic organisms. Under quite different conditions upper jaw protraction allows the jaw to cut deeply through food items too large to be swallowed whole. The feeding mechanism found in these sharks, therefore, seems to be well adapted to deal with a wide variety of food types.

@article{doi101111j146979981972tb01734x,
    author = "Moss, Sanford A.",
    title = "The feeding mechanism of sharks of the family Carcharhinidae",
    year = "1972",
    journal = "Journal of Zoology",
    abstract = "The morphology of thefeedingapparatus in several genera of carcharhinid sharks (Carcharhinus, Rhizoprionodon, Hypoprion, Prionace, Galeocerdo and Negaprion) was studied in both fresh and preserved states. The actions of the cranial musculature were determined through electrical stimulation. The feeding behaviours of representatives of the genera Carcharhinus, Negaprion and Galeocerdo were studied under controlled conditions by direct observation as well as photographically. The cranial anatomy of carcharhinid sharks is characterized by a relatively reduced chondrocranium and a greatly hypertrophied musculature. The hyostylic jaw suspension serves to allow substantial cranial kinesis, particularly with respect to the upper jaw. Protraction of this skeletal element is accomplished in at least two ways, depending on the external and internal forces applied to the palatoquadrate cartilage. Under one set of conditions upper jaw protraction serves to allow precision when feeding on benthic organisms. Under quite different conditions upper jaw protraction allows the jaw to cut deeply through food items too large to be swallowed whole. The feeding mechanism found in these sharks, therefore, seems to be well adapted to deal with a wide variety of food types.",
    url = "https://doi.org/10.1111/j.1469-7998.1972.tb01734.x",
    doi = "10.1111/j.1469-7998.1972.tb01734.x",
    openalex = "W2086819850"
}

@misc{ebbesson1972new3,
    author = "Ebbesson, S. O. E",
    title = "New insights into the organization of the shark brain",
    year = "1972",
    howpublished = "Comparative Biochemistry and Physiology, v. 42, p. 121-129",
    note = "talkorigins\_source = {true}; raw\_reference = {Ebbesson, S. O. E., 1972, New insights into the organization of the shark brain: Comparative Biochemistry and Physiology, v. 42, p. 121-129.}"
}

@misc{compagno1977phyletic1,
    author = "Compagno, L. J. V",
    title = "Phyletic relationships of living sharks and rays",
    year = "1977",
    howpublished = "American Zoologist, v. 17, p. 303-322",
    note = "talkorigins\_source = {true}; raw\_reference = {Compagno, L. J. V., 1977, Phyletic relationships of living sharks and rays: American Zoologist, v. 17, p. 303-322.}"
}

A set of hypotheses are developed for the origin of living sharks and rays and the interrelationships of their major groups, using some methods of cladistic analysis to relate groups with shared derived characters. Comparative studies on living sharks and rays combined with new data on fossil sharks suggests that the living groups ultimately stem from a common ancestral group of “neoselachian” sharks with many modern characters. Reinterpretations of “amphistyly” in modern sharks is presented on new data.

@article{doi101093icb172303,
    author = "Compagno, Leonard J. V.",
    title = "Phyletic Relationships of Living Sharks and Rays",
    year = "1977",
    journal = "American Zoologist",
    abstract = "A set of hypotheses are developed for the origin of living sharks and rays and the interrelationships of their major groups, using some methods of cladistic analysis to relate groups with shared derived characters. Comparative studies on living sharks and rays combined with new data on fossil sharks suggests that the living groups ultimately stem from a common ancestral group of “neoselachian” sharks with many modern characters. Reinterpretations of “amphistyly” in modern sharks is presented on new data.",
    url = "https://doi.org/10.1093/icb/17.2.303",
    doi = "10.1093/icb/17.2.303",
    openalex = "W2011454861",
    references = "doi101017cbo9781139680851, doi101038124440c0, doi101098rstb19210008, doi101111j146363951923tb00161x, doi101111j146979981936tb06287x, doi101111j146979981972tb01734x, doi1023071535500, openalexw1509085045, openalexw3041320757, openalexw3138434819"
}

@misc{gruber1977approaches6,
    author = "Gruber, S. H. and Myrberg, A. A. J",
    title = "Approaches to the study of the behavior of sharks",
    year = "1977",
    howpublished = "American Zoologist, v. 17, p. 471-486",
    note = "talkorigins\_source = {true}; raw\_reference = {Gruber, S. H., and Myrberg, A. A. J., 1977, Approaches to the study of the behavior of sharks: American Zoologist, v. 17, p. 471-486.}"
}

@misc{gruber1977the5,
    author = "Gruber, S. H",
    title = "The visual system of sharks, adaptations and capability",
    year = "1977",
    howpublished = "American Zoologist, v. 17, p. 453-469",
    note = "talkorigins\_source = {true}; raw\_reference = {Gruber, S. H., 1977, The visual system of sharks, adaptations and capability: American Zoologist, v. 17, p. 453-469.}"
}

Partial contents: Vision--Visual system of the Elasmobranchs (State of the art 1960-1975), Refraction and accommodations of the Elasmobranch eye, Brain organization in the Cartilaginous fishes, and Behavioral studies correlated with central nervous system integration of vision in sharks; Chemical Senses--Electrophysiological studies of chemoreception in Elasmobranchs, and Chemoreception and the role of its interaction with flow and light perception in the locomotion and orientation of some Elasmobranchs; Mechanical and Acoustical Senses--Mechanoreception and the behavior of Elasmobranch fishes with special reference to the acoustico-lateralis systems, Underwater sound (Its effect on shark's behavior), and Telemetering techniques for study of free-ranging sharks; Electrical Senses--Physiology of the Ampulla of Lorenzini, and Electric and magnetic sensory world of sharks, skates, and rays; and Ecology and Behavior- Dispersion of the Port Jackson shark in Australian waters, Problems in studies of sharks in the southwest Indian Ocean, Knowledge and exploitation of the sensory biology of sharks in the southwestern Pacific, and Effects of fasting confinement on Squalus acanthias.

@book{doi105962bhltitle3596,
    author = "Hodgson, Edward S. and Mathewson, Robert F.",
    title = "Sensory Biology of Sharks, Skates, and Rays,",
    year = "1978",
    booktitle = "Biodiversity Heritage Library (Smithsonian Institution)",
    abstract = "Partial contents: Vision--Visual system of the Elasmobranchs (State of the art 1960-1975), Refraction and accommodations of the Elasmobranch eye, Brain organization in the Cartilaginous fishes, and Behavioral studies correlated with central nervous system integration of vision in sharks; Chemical Senses--Electrophysiological studies of chemoreception in Elasmobranchs, and Chemoreception and the role of its interaction with flow and light perception in the locomotion and orientation of some Elasmobranchs; Mechanical and Acoustical Senses--Mechanoreception and the behavior of Elasmobranch fishes with special reference to the acoustico-lateralis systems, Underwater sound (Its effect on shark's behavior), and Telemetering techniques for study of free-ranging sharks; Electrical Senses--Physiology of the Ampulla of Lorenzini, and Electric and magnetic sensory world of sharks, skates, and rays; and Ecology and Behavior- Dispersion of the Port Jackson shark in Australian waters, Problems in studies of sharks in the southwest Indian Ocean, Knowledge and exploitation of the sensory biology of sharks in the southwestern Pacific, and Effects of fasting confinement on Squalus acanthias.",
    url = "https://doi.org/10.5962/bhl.title.3596",
    doi = "10.5962/bhl.title.3596",
    openalex = "W1794557058"
}

@book{openalexw595691412,
    author = "Zangerl, Rainer",
    title = "Chondrichthyes I: Paleozoic Elasmobranchii",
    year = "1981",
    booktitle = "G. Fischer eBooks",
    url = "https://openalex.org/W595691412",
    openalex = "W595691412"
}

Age and growth of the sandbar shark (Carcharhinus plumbeus) was determined from rings in the vertebrae of 475 individuals, tagging data from 220 sharks at liberty for up to 17 yr, and length–frequency data from 2594 individuals. The oldest male sandbar aged in this study was 15 yr old and 154 cm fork length (FL); the oldest female was 21 yr old and 204 cm FL. The sexes grew at similar rates, 5.2–7.3 cm/yr. Females reached a larger adult size. Age to maturity was estimated at 13 yr in males and 12 yr in females. Tag returns indicated that sandbar sharks may live for over 30 yr. von Bertalanffy parameters for males are L ∞ = 257, K = 0.0501, t 0 = −4.5 and for females are L ∞ = 299, K = 0.040, t 0 = −4.9.

@article{doi101139f85121,
    author = "Casey, John G. and Pratt, H. L. and Stillwell, C. E.",
    title = "Age and Growth of the Sandbar Shark (Carcharhinus plumbeus) from the Western North Atlantic",
    year = "1985",
    journal = "Canadian Journal of Fisheries and Aquatic Sciences",
    abstract = "Age and growth of the sandbar shark (Carcharhinus plumbeus) was determined from rings in the vertebrae of 475 individuals, tagging data from 220 sharks at liberty for up to 17 yr, and length–frequency data from 2594 individuals. The oldest male sandbar aged in this study was 15 yr old and 154 cm fork length (FL); the oldest female was 21 yr old and 204 cm FL. The sexes grew at similar rates, 5.2–7.3 cm/yr. Females reached a larger adult size. Age to maturity was estimated at 13 yr in males and 12 yr in females. Tag returns indicated that sandbar sharks may live for over 30 yr. von Bertalanffy parameters for males are L ∞ = 257, K = 0.0501, t 0 = −4.5 and for females are L ∞ = 299, K = 0.040, t 0 = −4.9.",
    url = "https://doi.org/10.1139/f85-121",
    doi = "10.1139/f85-121",
    openalex = "W2016067848",
    references = "openalexw2900647185"
}

@book{openalexw641496887,
    author = "Cappetta, Henri",
    title = "Chondrichthyes: Mesozoic and Cenozoic Elasmobranchii",
    year = "1987",
    booktitle = "G. Fischer Verlag eBooks",
    url = "https://openalex.org/W641496887",
    openalex = "W641496887"
}

@article{doi101007bf00539785,
    author = "Frazzetta, T. H.",
    title = "The mechanics of cutting and the form of shark teeth (Chondrichthyes, Elasmobranchii)",
    year = "1988",
    journal = "Zoomorphology",
    url = "https://doi.org/10.1007/bf00539785",
    doi = "10.1007/bf00539785",
    openalex = "W2030029189",
    references = "doi101002jmor1051180206, doi101038164766a0, doi101093bioscience1610752a, doi1023071445562, openalexw1521389098"
}

This book is a general review, taxonomic revision, and phylogenetic analysis of the carcharhinoids, the largest group of living sharks, which comprises almost 60 percent or 200 of known shark species. Students of shark biology have been hampered by the lack of just such a comprehensive and rigorous account of shark morphology. With this work L.J.V. Compagno offers not only the most comprehensive and detailed account of this important but neglected group to date but also one of the most comprehensive modern anatomical and phylogenetic studies on cartilaginous fishes available. It will become an essential reference not only for researchers on carcharhinoids but also for those who study other families of sharks and for paleontologists interested in this ancient group of fishes. The book begins with a general account of carcharhinoid sharks. Chapters Two through Eleven include detailed discussions of character systems used in taxonomic and phylogenetic analysis of carcharhinoids. Chapter Twelve defines the Order Carcharhiniformes, lists its families, and includes a taxonomic key to the families. Chapters Thirteen through Twenty review the eight carcharhinoid families, and Chapter Twenty-One is an extended discussion of the phylogeny of carcharhinoids, with cladistic analysis of taxa at various levels.

@article{doi1023071445465,
    author = "McEachran, John D. and Compagno, Leonard J. V.",
    title = "Sharks of the Order Carcharhiniformes",
    year = "1989",
    journal = "Copeia",
    abstract = "This book is a general review, taxonomic revision, and phylogenetic analysis of the carcharhinoids, the largest group of living sharks, which comprises almost 60 percent or 200 of known shark species. Students of shark biology have been hampered by the lack of just such a comprehensive and rigorous account of shark morphology. With this work L.J.V. Compagno offers not only the most comprehensive and detailed account of this important but neglected group to date but also one of the most comprehensive modern anatomical and phylogenetic studies on cartilaginous fishes available. It will become an essential reference not only for researchers on carcharhinoids but also for those who study other families of sharks and for paleontologists interested in this ancient group of fishes. The book begins with a general account of carcharhinoid sharks. Chapters Two through Eleven include detailed discussions of character systems used in taxonomic and phylogenetic analysis of carcharhinoids. Chapter Twelve defines the Order Carcharhiniformes, lists its families, and includes a taxonomic key to the families. Chapters Thirteen through Twenty review the eight carcharhinoid families, and Chapter Twenty-One is an extended discussion of the phylogeny of carcharhinoids, with cladistic analysis of taxa at various levels.",
    url = "https://doi.org/10.2307/1445465",
    doi = "10.2307/1445465",
    openalex = "W2044330064"
}

The size of most newborn sharks makes them susceptible to predation from their own kind and other large fishes. In the northwestern Atlantic, juvenile nursery grounds can be generally classified according to whether or not the young are exposed to such predatory risk. Several related factors-breeding frequency, litter size, size at birth, early growth rate-may help offset early natural mortality. These factors are counterbalanced by the different species in several different ways, producing numerous early life history strategies. In general, slow growing species are either born at relatively large sizes or use protected nursery grounds, whereas faster growing species tend to rely more on growth rates than the other factors.

@article{openalexw3008158973,
    author = "Branstetter, Steven",
    title = "Early Life-History Implications of Selected Carcharhinoid and Lamnoid Sharks of the Northwest Atlantic",
    year = "1990",
    journal = "W\&M Publish (College of William \& Mary)",
    abstract = "The size of most newborn sharks makes them susceptible to predation from their own kind and other large fishes. In the northwestern Atlantic, juvenile nursery grounds can be generally classified according to whether or not the young are exposed to such predatory risk. Several related factors-breeding frequency, litter size, size at birth, early growth rate-may help offset early natural mortality. These factors are counterbalanced by the different species in several different ways, producing numerous early life history strategies. In general, slow growing species are either born at relatively large sizes or use protected nursery grounds, whereas faster growing species tend to rely more on growth rates than the other factors.",
    openalex = "W3008158973"
}

The distribution, size composition, sex ratio, reproductive biology and diet of 17 species of shark from the families Triakidae, Hemigaleidae and Carcharhinidae from northern Australia were examined. In most of these species the sex ratio of the embryos is 1: 1, whereas in the post-partum populations there were significantly more males than females. The results indicate four broad reproductive strategies among these sharks. In most species reproduction was distinctly seasonal with individual females giving birth each Austral summer (annual cycle) after a gestation period of 9-12 months. A second group had a very similar cycle except that individual females gave birth every second year (biennial cycle). A third group had an annual cycle but breeding was continuous throughout the year, these were mostly small bottom-associated sharks. One species had a seasonal cycle but gave birth twice each year (biannual cycle) after a 6-month gestation. The average size at birth varied from 27 to 75 cm and the average litter size varied from 2 to 34. The size at birth was about 40% of the size at maturity, which in turn was about 70% of the maximum size. Diets ranged from omnivorous to highly selective. Fish was an important component of the diet in all but one species. There was evidence of partitioning of food resources among sympatric, morphologically similar, sharks.

@article{doi101071mf9910151,
    author = "Stevens, JD and McLoughlin, KJ",
    title = "Distribution, size and sex composition, reproductive biology and diet of sharks from Northern Australia",
    year = "1991",
    journal = "Australian Journal of Marine and Freshwater Research",
    abstract = "The distribution, size composition, sex ratio, reproductive biology and diet of 17 species of shark from the families Triakidae, Hemigaleidae and Carcharhinidae from northern Australia were examined. In most of these species the sex ratio of the embryos is 1: 1, whereas in the post-partum populations there were significantly more males than females. The results indicate four broad reproductive strategies among these sharks. In most species reproduction was distinctly seasonal with individual females giving birth each Austral summer (annual cycle) after a gestation period of 9-12 months. A second group had a very similar cycle except that individual females gave birth every second year (biennial cycle). A third group had an annual cycle but breeding was continuous throughout the year, these were mostly small bottom-associated sharks. One species had a seasonal cycle but gave birth twice each year (biannual cycle) after a 6-month gestation. The average size at birth varied from 27 to 75 cm and the average litter size varied from 2 to 34. The size at birth was about 40\% of the size at maturity, which in turn was about 70\% of the maximum size. Diets ranged from omnivorous to highly selective. Fish was an important component of the diet in all but one species. There was evidence of partitioning of food resources among sympatric, morphologically similar, sharks.",
    url = "https://doi.org/10.1071/mf9910151",
    doi = "10.1071/mf9910151",
    openalex = "W2046647019",
    references = "openalexw2900647185"
}

The ventral gill arch skeleton was examined in some representatives of batoid fishes. The homology of the components was elucidated by comparing similarities and differences among the components of the ventral gill arches in chondrichthyans, and attempts were made to justify the homology by giving causal mechanisms of chondrogenesis associated with the ventral gill arch skeleton. The ceratohyal is present in some batoid fishes, and its functional replacement, the pseudohyal, seems incomplete in most groups of batoid fishes, except in stingrays. The medial fusion of the pseudohyal with successive ceratobranchials occurs to varying degrees among stingray groups. The ankylosis between the last two ceratobranchials occurs uniquely in stingrays, and it serves as part of the insertion of the last pair of coracobranchialis muscles. The basihyal is possibly independently lost in electric rays, the stingray genus Urotrygon (except U. daviesi) and pelagic myliobatoid stingrays. The first hypobranchial is oriented anteriorly or anteromedially, and it varies in shape and size among batoid fishes. It is represented by rami projecting posterolaterally from the basihyal in sawfishes, guitarfishes and skates. It consists of a small piece of cartilage which extends anteromedially from the medial end of the first ccratobranchial in electric rays. It is a large cartilaginous plate in most of stingrays. It is absent in pelagic myliobatoid stingrays. The remaining hypobranchial cartilages also vary in shape and size among batoid fishes. Torpedo and possibly the Jurassic Belemnobalis and Spathobatis possess the generalized or typical chondrichthyan ventral gill arch structure in which the hypobranchials form a Σ-shaped pattern. In the electric ray Hypnos and narkinidid and narcinidid electric rays, the hypobranchial components are oriented longitudinally along the mid-portion of the ventral gill arches. They form a single cartilaginous plate in the narkinidid electric rays, Narcine and Diplobatis. In guitarfishes and skates, the second hypobranchial is unspecialized, and in skates, it does not have a direct contact with the second ceratobranchial. In both groups, the third and fourth hypobranchials are composed of a small cartilage which forms a passage for the afferent branches of the ventral aorta and serve as part of the insertion of the coracobranchialis muscle. In sawfishes and stingrays, the hypobranchials appear to be included in the medial plate. In sawfishes, the second and third components separately chondrify in adults, but the fourth component appears to be fused with the middle medial plate. In stingrays, a large medial plate appears to include the second through to the last hypobranchial and most of the basibranchial copulae. The medial plate probably develops independently in sawfishes and stingrays. Because the last basibranchial copula appears to be a composite of one to two hypobranchials and at least two basibranchial copulae, the medial plate may be formed by several developmental processes of chondrogenesis. More detailed comparative anatomical and developmental studies are needed to unveil morphogenesis and patternings of the ventral gill arch skeleton in batoid fishes.

@article{doi101111j109636421991tb01537x,
    author = "Miyake, Tsutomu and McEachran, John D.",
    title = "The morphology and evolution of the ventral gill arch skeleton in batoid fishes (Chondrichthyes: Batoidea)",
    year = "1991",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "The ventral gill arch skeleton was examined in some representatives of batoid fishes. The homology of the components was elucidated by comparing similarities and differences among the components of the ventral gill arches in chondrichthyans, and attempts were made to justify the homology by giving causal mechanisms of chondrogenesis associated with the ventral gill arch skeleton. The ceratohyal is present in some batoid fishes, and its functional replacement, the pseudohyal, seems incomplete in most groups of batoid fishes, except in stingrays. The medial fusion of the pseudohyal with successive ceratobranchials occurs to varying degrees among stingray groups. The ankylosis between the last two ceratobranchials occurs uniquely in stingrays, and it serves as part of the insertion of the last pair of coracobranchialis muscles. The basihyal is possibly independently lost in electric rays, the stingray genus Urotrygon (except U. daviesi) and pelagic myliobatoid stingrays. The first hypobranchial is oriented anteriorly or anteromedially, and it varies in shape and size among batoid fishes. It is represented by rami projecting posterolaterally from the basihyal in sawfishes, guitarfishes and skates. It consists of a small piece of cartilage which extends anteromedially from the medial end of the first ccratobranchial in electric rays. It is a large cartilaginous plate in most of stingrays. It is absent in pelagic myliobatoid stingrays. The remaining hypobranchial cartilages also vary in shape and size among batoid fishes. Torpedo and possibly the Jurassic Belemnobalis and Spathobatis possess the generalized or typical chondrichthyan ventral gill arch structure in which the hypobranchials form a Σ-shaped pattern. In the electric ray Hypnos and narkinidid and narcinidid electric rays, the hypobranchial components are oriented longitudinally along the mid-portion of the ventral gill arches. They form a single cartilaginous plate in the narkinidid electric rays, Narcine and Diplobatis. In guitarfishes and skates, the second hypobranchial is unspecialized, and in skates, it does not have a direct contact with the second ceratobranchial. In both groups, the third and fourth hypobranchials are composed of a small cartilage which forms a passage for the afferent branches of the ventral aorta and serve as part of the insertion of the coracobranchialis muscle. In sawfishes and stingrays, the hypobranchials appear to be included in the medial plate. In sawfishes, the second and third components separately chondrify in adults, but the fourth component appears to be fused with the middle medial plate. In stingrays, a large medial plate appears to include the second through to the last hypobranchial and most of the basibranchial copulae. The medial plate probably develops independently in sawfishes and stingrays. Because the last basibranchial copula appears to be a composite of one to two hypobranchials and at least two basibranchial copulae, the medial plate may be formed by several developmental processes of chondrogenesis. More detailed comparative anatomical and developmental studies are needed to unveil morphogenesis and patternings of the ventral gill arch skeleton in batoid fishes.",
    url = "https://doi.org/10.1111/j.1096-3642.1991.tb01537.x",
    doi = "10.1111/j.1096-3642.1991.tb01537.x",
    openalex = "W1978203077"
}

Sharks of the world:an annotated and illustrated catalogue of shark species known to date, Sharks of the world:an annotated and illustrated catalogue of shark species known to date, مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

@book{openalexw570265017,
    author = "Compagno, Leonard J. V.",
    title = "Sharks of the World: an Annotated and Illustrated Catalogue of Shark Species Known to Date",
    year = "1992",
    journal = "Medical Entomology and Zoology",
    abstract = "Sharks of the world:an annotated and illustrated catalogue of shark species known to date, Sharks of the world:an annotated and illustrated catalogue of shark species known to date, مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی",
    openalex = "W570265017"
}

Abstract A total of 63 species of skates (Chondrichthyes: Rajoidei) were surveyed, along with three species of the outgroup (Chondrichtyes: Rhinobatoidei) for electric organs along the sides of the tail. All skate specimens examined possessed what appeared to be functional electric organs, and the three species of the outgroup lacked evidence of electric organs. The electric organs were tail‐positive and arranged into horizontal columns divided by transverse septa. The electrocytes varied considerably within and among supraspecific taxa (subgenera and genera), but they could be broadly classified into cup‐shape, modified cup‐shape, intermediate‐shape, and disc‐shape cells, provided that the distinction was partially based on position of the electrocytes within their connective tissue chambers. The survey, in part, corroborates a phylogenetic hypothesis of skates and in some respects further resolves the hypothesis. The supraspecific taxa Atlantoraja and Rioraja have similar derived‐type electrocytes, as do the five supraspecific taxa of Rajini, and Cruriraja and Anacanthobatis, and to a lesser extent the supraspecific taxa Arhynchobatis, Psammobatis, and Sympterygia, and the supraspecific taxa Notoraja, Pavoraja, and Pseudoraja, corroborating the hypothesis. The supraspecific taxa Amblyraja, Rajella, Leucoraja, Breviraja, and Dactylobatus were unresolved in the phylogenetic hypothesis, but the electrocyte survey suggested that Leucoraja, Breviraja, and Dactylobatus were derived with respect to Amblyraja and Rajella. © 1994 Wiley‐Liss, Inc.

@article{doi101002jmor1052210104,
    author = "Jacob, Brian A. and McEachran, John D. and Lyons, Paul L.",
    title = "Electric organs in skates: Variation and phylogenetic significance (Chondrichthyes: Rajoidei)",
    year = "1994",
    journal = "Journal of Morphology",
    abstract = "Abstract A total of 63 species of skates (Chondrichthyes: Rajoidei) were surveyed, along with three species of the outgroup (Chondrichtyes: Rhinobatoidei) for electric organs along the sides of the tail. All skate specimens examined possessed what appeared to be functional electric organs, and the three species of the outgroup lacked evidence of electric organs. The electric organs were tail‐positive and arranged into horizontal columns divided by transverse septa. The electrocytes varied considerably within and among supraspecific taxa (subgenera and genera), but they could be broadly classified into cup‐shape, modified cup‐shape, intermediate‐shape, and disc‐shape cells, provided that the distinction was partially based on position of the electrocytes within their connective tissue chambers. The survey, in part, corroborates a phylogenetic hypothesis of skates and in some respects further resolves the hypothesis. The supraspecific taxa Atlantoraja and Rioraja have similar derived‐type electrocytes, as do the five supraspecific taxa of Rajini, and Cruriraja and Anacanthobatis, and to a lesser extent the supraspecific taxa Arhynchobatis, Psammobatis, and Sympterygia, and the supraspecific taxa Notoraja, Pavoraja, and Pseudoraja, corroborating the hypothesis. The supraspecific taxa Amblyraja, Rajella, Leucoraja, Breviraja, and Dactylobatus were unresolved in the phylogenetic hypothesis, but the electrocyte survey suggested that Leucoraja, Breviraja, and Dactylobatus were derived with respect to Amblyraja and Rajella. © 1994 Wiley‐Liss, Inc.",
    url = "https://doi.org/10.1002/jmor.1052210104",
    doi = "10.1002/jmor.1052210104",
    openalex = "W2034395060"
}

The waters around Australia are home to the greatest diversity of sharks and rays on Earth. Spookfish, numbfish, stingarees, fiddler rays and cookie-cutter sharks are just some of the 322 shark, ray and chimaerid species illustrated in the latest edition of Sharks and Rays of Australia. Australia's sharks, rays and chimaerids - collectively known as Chondrichthyans - are just as intriguing as their names suggest. Their eclectic colours, shapes and patterns reflect environments ranging from remote estuaries to ocean depths. Their new descriptions, and their striking portraits by watercolourist Roger Swainston, will help to guide the identification and conservation of these diverse species. The first edition of Sharks and Rays of Australia was produced in 1994. Since then, 29 species have been discovered in Australian seas and more than 100 species have been named and formally described. As well as documenting these advances, the new edition includes updated species classifications and descriptions, distribution maps, line illustrations by Georgina Davis, family keys and outlines of Chondrichthyan biology and interactions with humans. The book catalogues a rich seam of Australia's marine biodiversity, providing an indispensible compendium for scientists and a baseline reference for the fishing industry. Sharks and Rays of Australia is an essential reference for professional and recreational fishermen, divers, naturalists, students, fish and conservation biologists, and anyone interested in sharks and rays.

@article{doi1023071446735,
    author = "Springer, Victor G. and Last, Peter R. and Stevens, JD",
    title = "Sharks and Rays of Australia",
    year = "1994",
    journal = "Copeia",
    abstract = "The waters around Australia are home to the greatest diversity of sharks and rays on Earth. Spookfish, numbfish, stingarees, fiddler rays and cookie-cutter sharks are just some of the 322 shark, ray and chimaerid species illustrated in the latest edition of Sharks and Rays of Australia. Australia's sharks, rays and chimaerids - collectively known as Chondrichthyans - are just as intriguing as their names suggest. Their eclectic colours, shapes and patterns reflect environments ranging from remote estuaries to ocean depths. Their new descriptions, and their striking portraits by watercolourist Roger Swainston, will help to guide the identification and conservation of these diverse species. The first edition of Sharks and Rays of Australia was produced in 1994. Since then, 29 species have been discovered in Australian seas and more than 100 species have been named and formally described. As well as documenting these advances, the new edition includes updated species classifications and descriptions, distribution maps, line illustrations by Georgina Davis, family keys and outlines of Chondrichthyan biology and interactions with humans. The book catalogues a rich seam of Australia's marine biodiversity, providing an indispensible compendium for scientists and a baseline reference for the fishing industry. Sharks and Rays of Australia is an essential reference for professional and recreational fishermen, divers, naturalists, students, fish and conservation biologists, and anyone interested in sharks and rays.",
    url = "https://doi.org/10.2307/1446735",
    doi = "10.2307/1446735",
    openalex = "W2094622030"
}

Recent studies have shown that by 1991 the sandbar shark (Carcharhinus plumbeus) population along the Atlantic coast of the United States had declined in abundance to approximately 20% of its level in the late 1970s. This phenomenon allowed us to test the hypothesis that compensatory (density-dependent) growth occurred after severe population reduction. Age and growth of sandbar sharks were investigated by counting rings and back-calculating lengths at previous ages from vertebral samples collected in 1980-1981 and 1991-1992. The collections included 188 sharks from 1980-1981 and 412 sharks from 1990-1991 ranging in length from 51-172 cm precaudal length (PCL). All sharks were mature at lengths > 136 cm PCL. Minimum and maximum ring counts, which included a birth mark, were 1 and 25. Age at maturity was 15-16 years for both sample periods and both sexes. For sexes combined, the von Bertalanffy growth parameters were L,. = 199 cm PCL, K = 0.057, to = -4.9 years for the 1980-1981 sample and L,. = 164 cm PCL, K = 0.089, to = -3.8 years for the 1991-1992 sample. Statistical tests found significant differences between the two growth models. Significant differences in size at age and annual incremental growth of juveniles suggest a small increase in juvenile sandbar shark growth rate between the two sampling periods. However, age at maturity was unchanged between samples suggesting that any biological significance of a growth rate increase has not been realized.

@article{doi1023071447035,
    author = "Sminkey, Thomas R. and Musick, John A.",
    title = "Age and Growth of the Sandbar Shark, Carcharhinus plumbeus, before and after Population Depletion",
    year = "1995",
    journal = "Copeia",
    abstract = "Recent studies have shown that by 1991 the sandbar shark (Carcharhinus plumbeus) population along the Atlantic coast of the United States had declined in abundance to approximately 20\% of its level in the late 1970s. This phenomenon allowed us to test the hypothesis that compensatory (density-dependent) growth occurred after severe population reduction. Age and growth of sandbar sharks were investigated by counting rings and back-calculating lengths at previous ages from vertebral samples collected in 1980-1981 and 1991-1992. The collections included 188 sharks from 1980-1981 and 412 sharks from 1990-1991 ranging in length from 51-172 cm precaudal length (PCL). All sharks were mature at lengths > 136 cm PCL. Minimum and maximum ring counts, which included a birth mark, were 1 and 25. Age at maturity was 15-16 years for both sample periods and both sexes. For sexes combined, the von Bertalanffy growth parameters were L,. = 199 cm PCL, K = 0.057, to = -4.9 years for the 1980-1981 sample and L,. = 164 cm PCL, K = 0.089, to = -3.8 years for the 1991-1992 sample. Statistical tests found significant differences between the two growth models. Significant differences in size at age and annual incremental growth of juveniles suggest a small increase in juvenile sandbar shark growth rate between the two sampling periods. However, age at maturity was unchanged between samples suggesting that any biological significance of a growth rate increase has not been realized.",
    url = "https://doi.org/10.2307/1447035",
    doi = "10.2307/1447035",
    openalex = "W2332186382",
    references = "doi101007bf00004952, doi101139f81132, doi101139f85121, doi101139f88115, doi101139f90246, doi10157715488659197910814rfatas20co2, doi101577154886591983112735tfrfav20co2, openalexw227953458, openalexw2588677549, openalexw2900647185"
}

@incollection{doi101016b9780126709506500035,
    author = "Shirai, Shigeru",
    title = "Phylogenetic Interrelationships of Neoselachians (Chondrichthyes: Euselachii)",
    year = "1996",
    booktitle = "Elsevier eBooks",
    url = "https://doi.org/10.1016/b978-012670950-6/50003-5",
    doi = "10.1016/b978-012670950-6/50003-5",
    openalex = "W2909503525",
    references = "doi101038164766a0, doi101093bioscience1610752a, doi101093icb172303, doi101093sysbio33183, doi101111j146363951940tb00339x, doi1023072412293, doi1023072413134, openalexw2900647185, openalexw3041320757, openalexw3190442888, openalexw570265017"
}

@article{openalexw3211386673,
    author = "Shirai",
    title = "Phylogenetic interrelationships of neoselachians (Chondrichthyes: Euselachii)",
    year = "1996",
    journal = "(No Title)",
    url = "https://openalex.org/W3211386673",
    openalex = "W3211386673"
}

Contributors. Acknowledgments. Introduction: A.P. Klimley and D.G. Ainley, White Shark Research in the Past: A Perspective. R.C. Murphy, A Plea for White Shark Conservation. Evolution: G. Hubell, Using Tooth Structure to Determine the Evolutionary History of the White Shark. S.P. Applegate and L. Espinosa-Arrubarrena, The Fossil History of Carcharodon and Its Possible Ancestor, Cretolamna: A Study in Tooth Identification. D.J. Long and B.M. Waggoner, Evolutionary Relationships of the White Shark: A Phylogeny of Lamniform Sharks Based on Dental Morphology. A.P. Martin, Systematics of the Lamnidae and the Origination Time of Carcharodon carcharias Inferred from the Comparative Analysis of Mitochondrial DNA Sequences. M.D. Gottfried, L.J.V. Compagno, and S.C. Bowman, Size and Skeletal Anatomy of the Giant Megatooth Shark Carcharodon megalodon. R.W. Purdy, Paleoecology of Fossil White Sharks. Anatomy: H.F. Mollet and G.M. Cailliet, Using Allometry to Predict Body Mass from Linear Measurements of the White Shark. H.F. Mollet, G.M. Cailliet, A.P. Klimley, D.A. Ebert, A.D. Testi, and L.J.V. Compagno, A Review of Length Validation Methods and Protocols to Measure Large White Sharks. Physiology: K.J. Goldman, S.D. Anderson, J.E. McCosker, and A.P. Klimley, Temperature, Swimming Depth, and Movements of a White Shark at the South Farallon Islands, California. L.S. Demski and R.Gl. Northcutt, The Brain and Cranial Nerves of the White Shark: An Evolutionary Perspective. H.L. Pratt, Jr., Reproduction in the Male White Shark. S. Uchida, M. Toda, K. Teshima, and K. Yano, Pregnant White Sharks with Full-Term Embryos from Japan. M.P. Francis, Observations on a Pregnant White Shark with a Review of Reproductive Biology. Behavior: A.P. Klimley, P. Pyle, and S.D. Anderson, The Behavior of White Sharks and Their Pinniped Prey during Predatory Attacks. B.J. LeBoeuf and D.E. Crocker, Diving Behavior of Elephant Seals: Implications for Predator Avoidance. W.R. Strong, Jr., Repetitive Aerial Jaw Gaping: A Thwart-Induced Behavior in White Sharks. R.S. Collier, M. Marks, and R.W. Warner, White Shark Attacks on Inanimate Objects along the Pacific Coast of North America. S.D. Anderson, R.P. Henderson, P. Pyle, and D.G. Ainley, Observations of White Shark Reactions to Unbaited Decoys. W.R. Strong, Jr., Shape Discrimination and Visual Predatory Tactics in White Sharks. A.P. Klimley, P. Pyle, and S.D. Anderson, Tail Slap and Breach: Agonistic Displays among White Sharks? G.W. Barlow, Behavior of the White Shark: An Emerging Picture. Ecology and Distribution: D.J. Long, K.D. Hanni, P. Pyle, J. Roletto, R.E. Jones, and R. Bandar, White Shark Predation on Four Pinniped Species in Central California Waters: Geographic and Temporal Patterns Inferred from Wounded Carcasses. S.D. Anderson, A.P. Klimley, P. Pyle, and R.P. Henderson, Tidal Height and White Shark Predation at the South Farallon Islands, California. P. Pyle, S.D. Anderson, A.P. Klimley, and R.P. Henderson, Environmental Factors Affecting the Occurrence and Behavior of White Sharks at the Farallon Islands, California. D.J. Long and R.E. Jones, White Shark Predation and Scavenging on Cetaceans in the Eastern North Pacific Ocean. J.A. Ames, J.J. Geibel, F.E. Wendell, and C.A. Pattison, White Shark-Inflicted Wounds of Sea Otters in California, 1968-1992. D.J. Long, Records of White Shark-Bitten Leatherback Sea Turtles along the Central California Coast. I.K. Fergusson, Distribution and Autecology of the White Shark in the Eastern North Atlantic Ocean and the Mediterranean Sea. O.B.F. Gadig and R.S. Rosa, Occurrence of the White Shark along the Brazilian Coast. G. Cliff, S.F.J. Dudley, and M.R. Jury, Catches of White Sharks in KwaZulu-Natal, South Africa, and Environmental Influences. Population Biology: A.P. Klimley and S.D. Anderson, Residency Patterns of White Sharks at the South Farallon Islands, California. P. Pyle, S.D. Anderson, and D.G. Ainley, Trends in White Shark Predation at the South Farallon Islands, 1968-1993. C.A. Ferreira and T.P. Ferreira, Population Dynamics of White Sharks in South Africa. G. Cliff, R.P. Van Der Elst, A. Govender, T.K. Witthuhn, and E.M. Bullen, First Estimates of Mortality and Population Size on the South African Coast. W.R. Strong, Jr., B.D. Bruce, D.R. Nelson, and R.D. Murphy, Population Dynamics of White Sharks in Spencer Gulf, South Australia. G.M. Cailliet, An Evaluation of Methodologies to Study the Population Biology of White Sharks. Interactions with Humans: J.E. McCosker and R.N. Lea, White Shark Attacks in the Eastern Pacific Ocean: An Update and Analysis. M. Levine, Unprovoked Attacks by White Sharks off the South African Coast. J. West, White Shark Attacks in Australian Waters. G.H. Burgess and M. Callahan, Worldwide Patterns of White Shark Attacks on Humans. D.R. Nelson and W.R. Strong, Jr., Chemical Repellent Tests on White Sharks, with Comments on Repellent Delivery Methods. H.D. Baldridge, Jr., Comments on Means for Avoidance or Deterrence of White Shark Attacks on Humans. B. Heneman and M. Glazer, More Rare Than Dangerous: A Case Study of White Shark Conservation in California. Bibliography. Subject Index.

@book{openalexw596245786,
    author = "Klimley, A. Peter and Ainley, David G.",
    title = "Great white sharks: the biology of Carcharodon carcharias",
    year = "1996",
    abstract = "Contributors. Acknowledgments. Introduction: A.P. Klimley and D.G. Ainley, White Shark Research in the Past: A Perspective. R.C. Murphy, A Plea for White Shark Conservation. Evolution: G. Hubell, Using Tooth Structure to Determine the Evolutionary History of the White Shark. S.P. Applegate and L. Espinosa-Arrubarrena, The Fossil History of Carcharodon and Its Possible Ancestor, Cretolamna: A Study in Tooth Identification. D.J. Long and B.M. Waggoner, Evolutionary Relationships of the White Shark: A Phylogeny of Lamniform Sharks Based on Dental Morphology. A.P. Martin, Systematics of the Lamnidae and the Origination Time of Carcharodon carcharias Inferred from the Comparative Analysis of Mitochondrial DNA Sequences. M.D. Gottfried, L.J.V. Compagno, and S.C. Bowman, Size and Skeletal Anatomy of the Giant Megatooth Shark Carcharodon megalodon. R.W. Purdy, Paleoecology of Fossil White Sharks. Anatomy: H.F. Mollet and G.M. Cailliet, Using Allometry to Predict Body Mass from Linear Measurements of the White Shark. H.F. Mollet, G.M. Cailliet, A.P. Klimley, D.A. Ebert, A.D. Testi, and L.J.V. Compagno, A Review of Length Validation Methods and Protocols to Measure Large White Sharks. Physiology: K.J. Goldman, S.D. Anderson, J.E. McCosker, and A.P. Klimley, Temperature, Swimming Depth, and Movements of a White Shark at the South Farallon Islands, California. L.S. Demski and R.Gl. Northcutt, The Brain and Cranial Nerves of the White Shark: An Evolutionary Perspective. H.L. Pratt, Jr., Reproduction in the Male White Shark. S. Uchida, M. Toda, K. Teshima, and K. Yano, Pregnant White Sharks with Full-Term Embryos from Japan. M.P. Francis, Observations on a Pregnant White Shark with a Review of Reproductive Biology. Behavior: A.P. Klimley, P. Pyle, and S.D. Anderson, The Behavior of White Sharks and Their Pinniped Prey during Predatory Attacks. B.J. LeBoeuf and D.E. Crocker, Diving Behavior of Elephant Seals: Implications for Predator Avoidance. W.R. Strong, Jr., Repetitive Aerial Jaw Gaping: A Thwart-Induced Behavior in White Sharks. R.S. Collier, M. Marks, and R.W. Warner, White Shark Attacks on Inanimate Objects along the Pacific Coast of North America. S.D. Anderson, R.P. Henderson, P. Pyle, and D.G. Ainley, Observations of White Shark Reactions to Unbaited Decoys. W.R. Strong, Jr., Shape Discrimination and Visual Predatory Tactics in White Sharks. A.P. Klimley, P. Pyle, and S.D. Anderson, Tail Slap and Breach: Agonistic Displays among White Sharks? G.W. Barlow, Behavior of the White Shark: An Emerging Picture. Ecology and Distribution: D.J. Long, K.D. Hanni, P. Pyle, J. Roletto, R.E. Jones, and R. Bandar, White Shark Predation on Four Pinniped Species in Central California Waters: Geographic and Temporal Patterns Inferred from Wounded Carcasses. S.D. Anderson, A.P. Klimley, P. Pyle, and R.P. Henderson, Tidal Height and White Shark Predation at the South Farallon Islands, California. P. Pyle, S.D. Anderson, A.P. Klimley, and R.P. Henderson, Environmental Factors Affecting the Occurrence and Behavior of White Sharks at the Farallon Islands, California. D.J. Long and R.E. Jones, White Shark Predation and Scavenging on Cetaceans in the Eastern North Pacific Ocean. J.A. Ames, J.J. Geibel, F.E. Wendell, and C.A. Pattison, White Shark-Inflicted Wounds of Sea Otters in California, 1968-1992. D.J. Long, Records of White Shark-Bitten Leatherback Sea Turtles along the Central California Coast. I.K. Fergusson, Distribution and Autecology of the White Shark in the Eastern North Atlantic Ocean and the Mediterranean Sea. O.B.F. Gadig and R.S. Rosa, Occurrence of the White Shark along the Brazilian Coast. G. Cliff, S.F.J. Dudley, and M.R. Jury, Catches of White Sharks in KwaZulu-Natal, South Africa, and Environmental Influences. Population Biology: A.P. Klimley and S.D. Anderson, Residency Patterns of White Sharks at the South Farallon Islands, California. P. Pyle, S.D. Anderson, and D.G. Ainley, Trends in White Shark Predation at the South Farallon Islands, 1968-1993. C.A. Ferreira and T.P. Ferreira, Population Dynamics of White Sharks in South Africa. G. Cliff, R.P. Van Der Elst, A. Govender, T.K. Witthuhn, and E.M. Bullen, First Estimates of Mortality and Population Size on the South African Coast. W.R. Strong, Jr., B.D. Bruce, D.R. Nelson, and R.D. Murphy, Population Dynamics of White Sharks in Spencer Gulf, South Australia. G.M. Cailliet, An Evaluation of Methodologies to Study the Population Biology of White Sharks. Interactions with Humans: J.E. McCosker and R.N. Lea, White Shark Attacks in the Eastern Pacific Ocean: An Update and Analysis. M. Levine, Unprovoked Attacks by White Sharks off the South African Coast. J. West, White Shark Attacks in Australian Waters. G.H. Burgess and M. Callahan, Worldwide Patterns of White Shark Attacks on Humans. D.R. Nelson and W.R. Strong, Jr., Chemical Repellent Tests on White Sharks, with Comments on Repellent Delivery Methods. H.D. Baldridge, Jr., Comments on Means for Avoidance or Deterrence of White Shark Attacks on Humans. B. Heneman and M. Glazer, More Rare Than Dangerous: A Case Study of White Shark Conservation in California. Bibliography. Subject Index.",
    openalex = "W596245786"
}

@article{doi101023a1018471324332,
    author = "Lund, Richard and Grogan, Eileen D.",
    title = "Relationships of the Chimaeriformes and the basal radiation of the Chondrichthyes",
    year = "1997",
    journal = "Reviews in Fish Biology and Fisheries",
    url = "https://doi.org/10.1023/a:1018471324332",
    doi = "10.1023/a:1018471324332",
    openalex = "W1554344874",
    references = "doi101038142004a0, doi101093icb172303, doi101242dev103supplement155, doi105962bhltitle106607, doi105962bhltitle156765, doi105962bhltitle4275, doi105962bhltitle45918, doi105962bhltitle542, doi105962bhltitle70395, doi105962bhltitle82144, openalexw595691412"
}

Sharks and rays are thought to have a large number of independent origins of live–bearing. We examined evolutionary transitions to live–bearing and maternal input to embryos in this subclass by optimizing reproductive characters onto a composite phylogeny. Egg–laying (40 % of all species) is the likely ancestral reproductive mode for this clade, and there is evidence that live–bearing has evolved independently 9–10 times and maternal input 4–5 times. Most transitions (12–15) have been toward live–bearing with provisioning limited to yolk. These have occurred from egg–laying ancestors or live–bearing taxa that provide maternal input to embryos. Only 2–3 transitions have occurred in the other direction, i.e. away from yolk–only bearing. Egg–laying has evolved from live–bearing ancestors in skates, Rajidae (25 per cent of all species) and possibly in the zebra shark, Stegostoma fasciata. Thus, although there has been an overall trend toward the evolution of live–bearing in elesmobranchs, the evolution of additional maternal input has been extremely labile.

@article{doi101098rspb19970181,
    author = "Dulvy, Nicholas K. and Reynolds, John D.",
    title = "Evolutionary transitions among egg–laying, live–bearing and maternal inputs in sharks and rays",
    year = "1997",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "Sharks and rays are thought to have a large number of independent origins of live–bearing. We examined evolutionary transitions to live–bearing and maternal input to embryos in this subclass by optimizing reproductive characters onto a composite phylogeny. Egg–laying (40 \% of all species) is the likely ancestral reproductive mode for this clade, and there is evidence that live–bearing has evolved independently 9–10 times and maternal input 4–5 times. Most transitions (12–15) have been toward live–bearing with provisioning limited to yolk. These have occurred from egg–laying ancestors or live–bearing taxa that provide maternal input to embryos. Only 2–3 transitions have occurred in the other direction, i.e. away from yolk–only bearing. Egg–laying has evolved from live–bearing ancestors in skates, Rajidae (25 per cent of all species) and possibly in the zebra shark, Stegostoma fasciata. Thus, although there has been an overall trend toward the evolution of live–bearing in elesmobranchs, the evolution of additional maternal input has been extremely labile.",
    url = "https://doi.org/10.1098/rspb.1997.0181",
    doi = "10.1098/rspb.1997.0181",
    openalex = "W2112455215",
    references = "doi101016b9780126709506500035, doi101038357153a0, doi101093icb172303, doi101093icb172379, doi101093icb212473, doi1015159780691206981, doi102307jctvs32ssj, doi105860choice392183, openalexw3041320757, openalexw570265017"
}

John D. McEachran, Katherine A. Dunn, Phylogenetic Analysis of Skates, a Morphologically Conservative Clade of Elasmobranchs (Chondrichthyes: Rajidae), Copeia, Vol. 1998, No. 2 (May 1, 1998), pp. 271-290

@article{doi1023071447424,
    author = "McEachran, John D. and Dunn, Katherine A.",
    title = "Phylogenetic Analysis of Skates, a Morphologically Conservative Clade of Elasmobranchs (Chondrichthyes: Rajidae)",
    year = "1998",
    journal = "Copeia",
    abstract = "John D. McEachran, Katherine A. Dunn, Phylogenetic Analysis of Skates, a Morphologically Conservative Clade of Elasmobranchs (Chondrichthyes: Rajidae), Copeia, Vol. 1998, No. 2 (May 1, 1998), pp. 271-290",
    url = "https://doi.org/10.2307/1447424",
    doi = "10.2307/1447424",
    openalex = "W2025263435",
    references = "doi101002jmor1052210104, doi101002sici109746871996052282165aidjmor530co24, doi101007bf02987786, doi101111j109600311994tb00179x, doi101111j109636421991tb01537x, doi1023071440496, doi1023071443685, doi1023071446735, doi1023071446989, doi1023073514548"
}

Sharks and their relatives, the rays and chimaeras, are the diverse group of cartilaginous fishes that have evolved over 400 million years. Historically considered of low economic value to large-scale fisheries, today many of these fishes have become the target of directed commercial and recreational fisheries around the world, and they are increasingly taken in the by-catch of fisheries targeting other species. This report emphasizes the widely-acknowledged need to improve shark fishery monitoring, expand biological research and take management action. It serves as an introduction to the ecology, status and conservation of the sharks and their relatives for a general audience. Shark fisheries can only be managed sustainably, and shark populations remain viable, with the introduction of new conservation and management initiatives.

@book{openalexw161635134,
    author = "Bräutigam, Amie and Camhi, Merry D. and Fordham, Sonja V. and Fowler, Sarah and Musick, John A.",
    title = "Sharks and their Relatives: Ecology And Conservation",
    year = "1998",
    abstract = "Sharks and their relatives, the rays and chimaeras, are the diverse group of cartilaginous fishes that have evolved over 400 million years. Historically considered of low economic value to large-scale fisheries, today many of these fishes have become the target of directed commercial and recreational fisheries around the world, and they are increasingly taken in the by-catch of fisheries targeting other species. This report emphasizes the widely-acknowledged need to improve shark fishery monitoring, expand biological research and take management action. It serves as an introduction to the ecology, status and conservation of the sharks and their relatives for a general audience. Shark fisheries can only be managed sustainably, and shark populations remain viable, with the introduction of new conservation and management initiatives.",
    openalex = "W161635134",
    references = "doi1023071447035"
}

Sharks are marine consumers believed to occupy top positions in marine food webs. But surprisingly, trophic level estimates for these predators are almost non-existent. With the hope of helping better define the ecological role of sharks in marine communities, this paper presents standardized diet compositions and trophic levels calculated for a suite of species. Dietary composition for each species was derived from published quantitative studies using a weighted average index that takes into account sample size in each study. The trophic level (TL) values of the 11 food types used to characterize the diet (obtained from published accounts) were then used to calculate fractional trophic levels for 149 species representing eight orders and 23 families. Sharks as a group are tertiary consumers (TL>4), and significant differences were found among the six orders compared, which were attributable to differences between orectolobiforms (TL<4) and all other orders, and between hexanchiforms and both carcharhiniforms and squatiniforms. Among four families of carcharhiniform sharks, carcharhinids (TL=4.1, n=39) had a significantly higher TL than triakids (TL=3.8, n=19) and scyliorhinids (TL=3.9, n=21), but not sphyrnids (TL=3.9, n=6). When compared to trophic levels for other top predators of marine communities obtained from the literature, mean TL for sharks was significantly higher than for seabirds (n=28), but not for marine mammals (n=97). Trophic level and body size were positively correlated (r s =0.33), with the fit increasing (r s =0.41) when the three predominantly zooplanktivorous sharks were omitted, and especially when considering only carcharhinid sharks (r s =0.55).

@article{doi101006jmsc19990489,
    author = "Cortés, Enric",
    title = "Standardized diet compositions and trophic levels of sharks",
    year = "1999",
    journal = "ICES Journal of Marine Science",
    abstract = "Sharks are marine consumers believed to occupy top positions in marine food webs. But surprisingly, trophic level estimates for these predators are almost non-existent. With the hope of helping better define the ecological role of sharks in marine communities, this paper presents standardized diet compositions and trophic levels calculated for a suite of species. Dietary composition for each species was derived from published quantitative studies using a weighted average index that takes into account sample size in each study. The trophic level (TL) values of the 11 food types used to characterize the diet (obtained from published accounts) were then used to calculate fractional trophic levels for 149 species representing eight orders and 23 families. Sharks as a group are tertiary consumers (TL>4), and significant differences were found among the six orders compared, which were attributable to differences between orectolobiforms (TL<4) and all other orders, and between hexanchiforms and both carcharhiniforms and squatiniforms. Among four families of carcharhiniform sharks, carcharhinids (TL=4.1, n=39) had a significantly higher TL than triakids (TL=3.8, n=19) and scyliorhinids (TL=3.9, n=21), but not sphyrnids (TL=3.9, n=6). When compared to trophic levels for other top predators of marine communities obtained from the literature, mean TL for sharks was significantly higher than for seabirds (n=28), but not for marine mammals (n=97). Trophic level and body size were positively correlated (r s =0.33), with the fit increasing (r s =0.41) when the three predominantly zooplanktivorous sharks were omitted, and especially when considering only carcharhinid sharks (r s =0.55).",
    url = "https://doi.org/10.1006/jmsc.1999.0489",
    doi = "10.1006/jmsc.1999.0489",
    openalex = "W2130534187",
    references = "doi101006jmsc19970280, doi101007978146123498212, doi1010160304380092900168, doi101016s0065288108600772, doi101038374255a0, doi101126science150369228, doi101126science2795352860, doi101139f96316, doi1023075256, doi103354meps084009"
}

A demographic technique is used to compare the intrinsic rates of population increase of 26 shark species hypothetically exposed to fishing mortality. These rates (r 2M) are used as a measure of the relative ability of different sharks to recover from fishing pressure. The method incorporates concepts of density dependence from standard population modelling and uses female age at maturity, maximum reproductive age, and average fecundity. A compensatory response to population reduction is assumed in pre-adult survival to the extent possible given the constraints of the life-history parameters. ‘Rebound’ productivity was strongly affected by age at maturity and little affected by maximum age. Species with lowest values (r 2M &lt; 0.04) tended to be late-maturing medium- to large-sized coastal sharks, whereas those with the highest (&gt; 0.08) were small coastal, early-maturing species. Sharks with mid-range values (r 2M = 0.04–0.07) were mostly large (&gt; 250 cm maximum size) pelagic species, relatively fast growing and early maturing. Possible selection pressures for these three shark groups, management implications, practical applications for the derived parameter r 2M, and recommended areas of research are discussed.

@article{doi101071mf97135,
    author = "Smith, Susan E. and Au, David W. and Show, Christina",
    title = "Intrinsic rebound potentials of 26 species of Pacific sharks",
    year = "1999",
    journal = "Marine and Freshwater Research",
    abstract = "A demographic technique is used to compare the intrinsic rates of population increase of 26 shark species hypothetically exposed to fishing mortality. These rates (r 2M) are used as a measure of the relative ability of different sharks to recover from fishing pressure. The method incorporates concepts of density dependence from standard population modelling and uses female age at maturity, maximum reproductive age, and average fecundity. A compensatory response to population reduction is assumed in pre-adult survival to the extent possible given the constraints of the life-history parameters. ‘Rebound’ productivity was strongly affected by age at maturity and little affected by maximum age. Species with lowest values (r 2M \< 0.04) tended to be late-maturing medium- to large-sized coastal sharks, whereas those with the highest (\> 0.08) were small coastal, early-maturing species. Sharks with mid-range values (r 2M = 0.04–0.07) were mostly large (\> 250 cm maximum size) pelagic species, relatively fast growing and early maturing. Possible selection pressures for these three shark groups, management implications, practical applications for the derived parameter r 2M, and recommended areas of research are discussed.",
    url = "https://doi.org/10.1071/mf97135",
    doi = "10.1071/mf97135",
    openalex = "W2108848485",
    references = "doi1023071447035, openalexw570265017"
}

Sharks and other chondrichthyans are often described as long lived, slow growing and producing few offspring. These biological characteristics, together with the common assumption that recruitment is directly related to stock, and pessimistic stock prognoses obtained from application of demographic analysis, have led to doubts that sharks can be harvested sustainably. Developed over the past 40 or so years from studies of only a few shark species, these doubts have been reinforced by declining catch rates in industrial, artisanal and recreational fisheries and in fishing programmes designed to reduce the risk of sharks attacking humans at bathing beaches. However, more recent studies and application of modelling techniques allowing for density-dependent responses to the effects of stock reduction indicate that shark stocks can be harvested sustainably and, if carefully managed, can provide very stable fisheries. It is now understood that some species (such as Galeorhinus galeus, Carcharhinus plumbeus, Carcharodon carcharias and several species of dogfish) have low productivity, whereas other species (such as Mustelus antarcticus, Rhizoprionodon terraenovae, Sphyrna tiburo and Prionace glauca) have higher productivity. This paper reviews the use of shark products, the effects of fishing on shark populations of the world, and recent developments in assessment of shark fishery stocks.

@article{doi101071mf98017,
    author = "Walker, Terence I.",
    title = "Can shark resources be harvested sustainably? A question revisited with a review of shark fisheries",
    year = "1999",
    journal = "Marine and Freshwater Research",
    abstract = "Sharks and other chondrichthyans are often described as long lived, slow growing and producing few offspring. These biological characteristics, together with the common assumption that recruitment is directly related to stock, and pessimistic stock prognoses obtained from application of demographic analysis, have led to doubts that sharks can be harvested sustainably. Developed over the past 40 or so years from studies of only a few shark species, these doubts have been reinforced by declining catch rates in industrial, artisanal and recreational fisheries and in fishing programmes designed to reduce the risk of sharks attacking humans at bathing beaches. However, more recent studies and application of modelling techniques allowing for density-dependent responses to the effects of stock reduction indicate that shark stocks can be harvested sustainably and, if carefully managed, can provide very stable fisheries. It is now understood that some species (such as Galeorhinus galeus, Carcharhinus plumbeus, Carcharodon carcharias and several species of dogfish) have low productivity, whereas other species (such as Mustelus antarcticus, Rhizoprionodon terraenovae, Sphyrna tiburo and Prionace glauca) have higher productivity. This paper reviews the use of shark products, the effects of fishing on shark populations of the world, and recent developments in assessment of shark fishery stocks.",
    url = "https://doi.org/10.1071/mf98017",
    doi = "10.1071/mf98017",
    openalex = "W1969769143"
}

The impact of fishing on chondrichthyan stocks around the world is currently the focus of considerable international concern. Most chondrichthyan populations are of low productivity relative to teleost fishes, a consequence of their different life-history strategies. This is reflected in the poor record of sustainability of target shark fisheries. Most sharks and some batoids are predators at, or near, the top of marine food webs. The effects of fishing are examined at the single-species level and through trophic interactions. We summarize the status of chondrichthyan fisheries from around the world. Some 50% of the estimated global catch of chondrichthyans is taken as by-catch, does not appear in official fishery statistics, and is almost totally unmanaged. When taken as by-catch, they are often subjected to high fishing mortality directed at teleost target species. Consequently, some skates, sawfish, and deep-water dogfish have been virtually extirpated from large regions. Some chondrichthyans are more resilient to fishing and we examine predictions on the vulnerability of different species based on their life-history and population parameters. At the species level, fishing may alter size structure and population parameters in response to changes in species abundance. We review the evidence for such density-dependent change. Fishing can affect trophic interactions and we examine cases of apparent species replacement and shifts in community composition. Sharks and rays learn to associate trawlers with food and feeding on discards may increase their populations. Using ECOSIM, we make some predictions about the long-term response of ecosystems to fishing on sharks. Three different environments are analysed: a tropical shelf ecosystem in Venezuela, a Hawaiian coral reef ecosystem, and a North Pacific oceanic ecosystem.

@article{doi101006jmsc20000724,
    author = "Stevens, John D.",
    title = "The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems",
    year = "2000",
    journal = "ICES Journal of Marine Science",
    abstract = "The impact of fishing on chondrichthyan stocks around the world is currently the focus of considerable international concern. Most chondrichthyan populations are of low productivity relative to teleost fishes, a consequence of their different life-history strategies. This is reflected in the poor record of sustainability of target shark fisheries. Most sharks and some batoids are predators at, or near, the top of marine food webs. The effects of fishing are examined at the single-species level and through trophic interactions. We summarize the status of chondrichthyan fisheries from around the world. Some 50\% of the estimated global catch of chondrichthyans is taken as by-catch, does not appear in official fishery statistics, and is almost totally unmanaged. When taken as by-catch, they are often subjected to high fishing mortality directed at teleost target species. Consequently, some skates, sawfish, and deep-water dogfish have been virtually extirpated from large regions. Some chondrichthyans are more resilient to fishing and we examine predictions on the vulnerability of different species based on their life-history and population parameters. At the species level, fishing may alter size structure and population parameters in response to changes in species abundance. We review the evidence for such density-dependent change. Fishing can affect trophic interactions and we examine cases of apparent species replacement and shifts in community composition. Sharks and rays learn to associate trawlers with food and feeding on discards may increase their populations. Using ECOSIM, we make some predictions about the long-term response of ecosystems to fishing on sharks. Three different environments are analysed: a tropical shelf ecosystem in Venezuela, a Hawaiian coral reef ecosystem, and a North Pacific oceanic ecosystem.",
    url = "https://doi.org/10.1006/jmsc.2000.0724",
    doi = "10.1006/jmsc.2000.0724",
    openalex = "W2121792431",
    references = "doi101006jmsc19990489, doi101098rspb19970181, doi101126science2795352860, doi1023071447035, doi1023071447424"
}

ABSTRACT This study examines life history patterns and correlations between traits related to body size, reproduction, age, and growth in sharks, using data from 230 populations representing 164 species, 19 families, and 7 orders. The analysis focused on interspecific life history variability, but intraspecific and intrapopulation variation were also considered. Interspecifically, body size correlated positively with litter size and offspring size, and a tradeoff between litter size and offspring size was found after factoring out the effects of body size. Offspring size correlated negatively with growth completion rate (K), but the correlation became positive after correcting for the effects of body size. Parental size for males and females was negatively correlated with K. Parental size and size at maturity exhibited a strong positive correlation, with sexual maturity occurring at about 75% of maximum size in both sexes. Males were 10% smaller than females and reached their maximum length 34% faster than females on average. Females tend to mature later and live longer than males, but age at maturity is reached at about 50% of maximum age in both sexes. Maximum size and empirical longevity were not significantly correlated in females, but were positively correlated in males. Size and age at maturity also exhibited a moderate positive correlation in males, especially after excluding data for Squalus acanthias. Principal component and cluster analyses were used to reflect similarities among life history traits of 40 populations from 34 species, and at least three separate life history strategies were identified.

@article{doi10108010408340308951115,
    author = "Cortés, Enric",
    title = "Life History Patterns and Correlations in Sharks",
    year = "2000",
    journal = "Reviews in Fisheries Science",
    abstract = "ABSTRACT This study examines life history patterns and correlations between traits related to body size, reproduction, age, and growth in sharks, using data from 230 populations representing 164 species, 19 families, and 7 orders. The analysis focused on interspecific life history variability, but intraspecific and intrapopulation variation were also considered. Interspecifically, body size correlated positively with litter size and offspring size, and a tradeoff between litter size and offspring size was found after factoring out the effects of body size. Offspring size correlated negatively with growth completion rate (K), but the correlation became positive after correcting for the effects of body size. Parental size for males and females was negatively correlated with K. Parental size and size at maturity exhibited a strong positive correlation, with sexual maturity occurring at about 75\% of maximum size in both sexes. Males were 10\% smaller than females and reached their maximum length 34\% faster than females on average. Females tend to mature later and live longer than males, but age at maturity is reached at about 50\% of maximum age in both sexes. Maximum size and empirical longevity were not significantly correlated in females, but were positively correlated in males. Size and age at maturity also exhibited a moderate positive correlation in males, especially after excluding data for Squalus acanthias. Principal component and cluster analyses were used to reflect similarities among life history traits of 40 populations from 34 species, and at least three separate life history strategies were identified.",
    url = "https://doi.org/10.1080/10408340308951115",
    doi = "10.1080/10408340308951115",
    openalex = "W2060076315",
    references = "doi1023071447035, openalexw2900647185, openalexw570265017"
}

Ichthyology & Herpetology (formerly Copeia) publishes work on the biology of fishes, amphibians, and reptiles, or work using those organisms as models for testing hypotheses of broad significance.

@article{doi1016430045851120000000635br20co2,
    author = "Luer, Carl A.",
    title = "Sharks, Skates, and Rays: The Biology of Elasmobranch Fishes",
    year = "2000",
    journal = "Copeia",
    abstract = "Ichthyology \& Herpetology (formerly Copeia) publishes work on the biology of fishes, amphibians, and reptiles, or work using those organisms as models for testing hypotheses of broad significance.",
    url = "https://doi.org/10.1643/0045-8511(2000)000[0635:br]2.0.co;2",
    doi = "10.1643/0045-8511(2000)000[0635:br]2.0.co;2",
    openalex = "W2097502711"
}

The dentitions of lamniform sharks are said to exhibit a unique heterodonty called the "lamnoid tooth pattern." The presence of an inflated hollow "dental bulla" on each jaw cartilage allows the recognition of homologous teeth across most modern macrophagous lamniforms based on topographic correspondence through the "similarity test." In most macrophagous lamniforms, three tooth rows are supported by the upper dental bulla: two rows of large anterior teeth followed by a row of small intermediate teeth. The lower tooth row occluding between the two rows of upper anterior teeth is the first lower anterior tooth row. Like the first and second lower anterior tooth rows, the third lower tooth row is supported by the dental bulla and may be called the first lower intermediate tooth row. The lower intermediate tooth row occludes between the first and second upper lateral tooth rows situated distal to the upper dental bulla, and the rest of the upper and lower tooth rows, all called lateral tooth rows, occlude alternately. Tooth symmetry cannot be used to identify their dental homology. The presence of dental bullae can be regarded as a synapomorphy of Lamniformes and this character is more definable than the "lamnoid tooth pattern." The formation of the tooth pattern appears to be related to the evolution of dental bullae. This study constitutes the first demonstration of supraspecific tooth-to-tooth dental homologies in nonmammalian vertebrates.

@article{doi101002jmor1073,
    author = "Shimada, Kenshu",
    title = "Dental homologies in lamniform sharks (Chondrichthyes: Elasmobranchii)",
    year = "2001",
    journal = "Journal of Morphology",
    abstract = {The dentitions of lamniform sharks are said to exhibit a unique heterodonty called the "lamnoid tooth pattern." The presence of an inflated hollow "dental bulla" on each jaw cartilage allows the recognition of homologous teeth across most modern macrophagous lamniforms based on topographic correspondence through the "similarity test." In most macrophagous lamniforms, three tooth rows are supported by the upper dental bulla: two rows of large anterior teeth followed by a row of small intermediate teeth. The lower tooth row occluding between the two rows of upper anterior teeth is the first lower anterior tooth row. Like the first and second lower anterior tooth rows, the third lower tooth row is supported by the dental bulla and may be called the first lower intermediate tooth row. The lower intermediate tooth row occludes between the first and second upper lateral tooth rows situated distal to the upper dental bulla, and the rest of the upper and lower tooth rows, all called lateral tooth rows, occlude alternately. Tooth symmetry cannot be used to identify their dental homology. The presence of dental bullae can be regarded as a synapomorphy of Lamniformes and this character is more definable than the "lamnoid tooth pattern." The formation of the tooth pattern appears to be related to the evolution of dental bullae. This study constitutes the first demonstration of supraspecific tooth-to-tooth dental homologies in nonmammalian vertebrates.},
    url = "https://doi.org/10.1002/jmor.1073",
    doi = "10.1002/jmor.1073",
    openalex = "W1979500189",
    references = "doi101002ajpa1330400210, doi101002jmor1051670308, doi101016b9780126709506500035, doi101093icb172303, doi101093oxfordjournalsmolbeva040523, doi101111j109600311991tb00045x, doi101111j155856461982tb05453x, doi101146annureven10010165000525, doi1023072412482, doi1023072413454, doi105860choice321516, doi105860choice383310"
}

Abstract The importance of interactions between sharks and cetaceans has been a subject of much conjecture, but few studies have addressed these interactions. Sharks (order Selachii) have been hypothesized to be important predators on dolphins and porpoises (suborder Odontoceti). Unfortunately, there are often few data to back up claims that certain shark species are major threats to cetaceans. To help identify potential shark predators in specific locations, available data on interactions with odontocetes for all shark species that may include cetaceans in their diet are reviewed. Shark species are categorized into groups based on predatory interactions with dolphins and porpoises (regular predators, occasional predators, potential predators, ectoparasites and insufficient data). Several shark species that have been overlooked in the cetacean literature are identified as potentially important predators while others that have been suspected to be important predators are probably at most occasional predators. How shark predation can influence dolphin populations, habitat use, group size and behaviour is discussed. How risk of shark predation can vary with habitat attributes in both nearshore and pelagic waters is also discussed. Predator–prey interactions have been the focus of most studies of shark–dolphin interaction, but competitive interactions may also occur. The first analysis of shark–dolphin dietary overlap is presented, which shows it to be significant between common dolphins and several species of sharks, including species that prey upon these dolphins.

@article{doi101017s0952836901000061,
    author = "Heithaus, Michael R.",
    title = "Predator–prey and competitive interactions between sharks (order Selachii) and dolphins (suborder Odontoceti): a review",
    year = "2001",
    journal = "Journal of Zoology",
    abstract = "Abstract The importance of interactions between sharks and cetaceans has been a subject of much conjecture, but few studies have addressed these interactions. Sharks (order Selachii) have been hypothesized to be important predators on dolphins and porpoises (suborder Odontoceti). Unfortunately, there are often few data to back up claims that certain shark species are major threats to cetaceans. To help identify potential shark predators in specific locations, available data on interactions with odontocetes for all shark species that may include cetaceans in their diet are reviewed. Shark species are categorized into groups based on predatory interactions with dolphins and porpoises (regular predators, occasional predators, potential predators, ectoparasites and insufficient data). Several shark species that have been overlooked in the cetacean literature are identified as potentially important predators while others that have been suspected to be important predators are probably at most occasional predators. How shark predation can influence dolphin populations, habitat use, group size and behaviour is discussed. How risk of shark predation can vary with habitat attributes in both nearshore and pelagic waters is also discussed. Predator–prey interactions have been the focus of most studies of shark–dolphin interaction, but competitive interactions may also occur. The first analysis of shark–dolphin dietary overlap is presented, which shows it to be significant between common dolphins and several species of sharks, including species that prey upon these dolphins.",
    url = "https://doi.org/10.1017/s0952836901000061",
    doi = "10.1017/s0952836901000061",
    openalex = "W2162273735",
    references = "doi101007bf00005044, doi101016b9780124150317500288, openalexw3190442888"
}

Previous research suggests that nursery areas provide an abundant food source as well as protection from predation for young sharks, and that these benefits are the reasons they use these areas. This study examined the abundance of prey species within a known nursery area, Terra Ceia Bay, Florida, and compared those data with the amount of time blacktip sharks spent within various geographic zones within the nursery. The most abundant prey species within the study site were pinfish, Lagodon rhomboides, pigfish, Orthopristis chrysoptera, spotfin mojarra, Eucinostomus argenteus, and silver perch, Bairdiella chrysoura. Prey species were found to be most abundant in the mid to southern portion of the nursery area, whereas sharks spent the majority of their time within the northern portion of the study site. There was no correlation between the amount of time sharks (as a whole and by individual) spent within a geographic zone and the abundance of prey species within that area. These results suggest that prey abundance is not the main factor directing the movement patterns and habitat choice of juvenile Carcharhinus limbatus within Terra Ceia Bay. Predator avoidance may be more important in the use of the nursery grounds by these young animals than prey abundance.

@article{doi101071mf01132,
    author = "Heupel, Michelle R. and Hueter, Robert E.",
    title = "Importance of prey density in relation to the movement patterns of juvenile blacktip sharks (Carcharhinus limbatus) within a coastal nursery area",
    year = "2002",
    journal = "Marine and Freshwater Research",
    abstract = "Previous research suggests that nursery areas provide an abundant food source as well as protection from predation for young sharks, and that these benefits are the reasons they use these areas. This study examined the abundance of prey species within a known nursery area, Terra Ceia Bay, Florida, and compared those data with the amount of time blacktip sharks spent within various geographic zones within the nursery. The most abundant prey species within the study site were pinfish, Lagodon rhomboides, pigfish, Orthopristis chrysoptera, spotfin mojarra, Eucinostomus argenteus, and silver perch, Bairdiella chrysoura. Prey species were found to be most abundant in the mid to southern portion of the nursery area, whereas sharks spent the majority of their time within the northern portion of the study site. There was no correlation between the amount of time sharks (as a whole and by individual) spent within a geographic zone and the abundance of prey species within that area. These results suggest that prey abundance is not the main factor directing the movement patterns and habitat choice of juvenile Carcharhinus limbatus within Terra Ceia Bay. Predator avoidance may be more important in the use of the nursery grounds by these young animals than prey abundance.",
    url = "https://doi.org/10.1071/mf01132",
    doi = "10.1071/mf01132",
    openalex = "W1554743409"
}

@article{doi101016s1055790302003330,
    author = "Douady, Christophe J. and Dosay, Miné and Shivji, Mahmood S. and Stanhope, Michael J.",
    title = "Molecular phylogenetic evidence refuting the hypothesis of Batoidea (rays and skates) as derived sharks",
    year = "2003",
    journal = "Molecular Phylogenetics and Evolution",
    url = "https://doi.org/10.1016/s1055-7903(02)00333-0",
    doi = "10.1016/s1055-7903(02)00333-0",
    openalex = "W2051992638",
    references = "openalexw3211386673"
}

Life-history traits (size at age, growth rates, size and age at maturity, size of near-term embryos and litter sizes) of bonnetheads, Sphyrna tiburo, were analysed to test for latitudinal differences by comparing data collected from three areas along Florida's Gulf of Mexico coastline between March 1998 and September 2000. A total of 539 sharks were collected during the study: 207 in north-west Florida (latitude ~30°N), 176 in Tampa Bay (~28°N) and 156 in Florida Bay (~25°N). Male and female bonnetheads in north-west Florida had the largest predicted asymptotic sizes (1007&nbsp;mm and 1398&nbsp;mm TL, respectively) and attained the largest estimated median size at maturity (830&nbsp;mm and 944&nbsp;mm, respectively) and the oldest estimated median age at maturity (3.0+&nbsp;years and 4.0+&nbsp;years, respectively). The largest near-term embryos (297&nbsp;mm TL) were also collected at the highest latitude, but no latitudinal difference in litter size was found. These differences in life-history traits provide supporting evidence that a pattern of latitudinal variation exists. Male and female bonnetheads in north-west Florida also had the fastest growth rate compared with the other locations, supporting the hypothesis that growth rate is inversely related to the length of the growing season (i.e. a pattern of countergradient variation exists).

@article{doi101071mf03023,
    author = "Lombardi-Carlson, L. and Cortés, Enric and Parsons, Glenn R. and Manire, Charles A.",
    title = "Latitudinal variation in life-history traits of bonnethead sharks, Sphyrna tiburo, (Carcharhiniformes: Sphyrnidae) from the eastern Gulf of Mexico",
    year = "2003",
    journal = "Marine and Freshwater Research",
    abstract = "Life-history traits (size at age, growth rates, size and age at maturity, size of near-term embryos and litter sizes) of bonnetheads, Sphyrna tiburo, were analysed to test for latitudinal differences by comparing data collected from three areas along Florida's Gulf of Mexico coastline between March 1998 and September 2000. A total of 539 sharks were collected during the study: 207 in north-west Florida (latitude \textasciitilde 30°N), 176 in Tampa Bay (\textasciitilde 28°N) and 156 in Florida Bay (\textasciitilde 25°N). Male and female bonnetheads in north-west Florida had the largest predicted asymptotic sizes (1007\ mm and 1398\ mm TL, respectively) and attained the largest estimated median size at maturity (830\ mm and 944\ mm, respectively) and the oldest estimated median age at maturity (3.0+\ years and 4.0+\ years, respectively). The largest near-term embryos (297\ mm TL) were also collected at the highest latitude, but no latitudinal difference in litter size was found. These differences in life-history traits provide supporting evidence that a pattern of latitudinal variation exists. Male and female bonnetheads in north-west Florida also had the fastest growth rate compared with the other locations, supporting the hypothesis that growth rate is inversely related to the length of the growing season (i.e. a pattern of countergradient variation exists).",
    url = "https://doi.org/10.1071/mf03023",
    doi = "10.1071/mf03023",
    openalex = "W1617492308",
    references = "doi101002jmor1051060104, doi101007bf00317554, doi10108010408340308951115, doi101086282929, doi101111j155856461990tb05198x, doi101139f81132, doi101139f82158, doi1012019781439894170, doi1023071940241, openalexw2588677549"
}

Overexploitation threatens the future of many large vertebrates. In the ocean, tunas and sea turtles are current conservation concerns because of this intense pressure. The status of most shark species, in contrast, remains uncertain. Using the largest data set in the Northwest Atlantic, we show rapid large declines in large coastal and oceanic shark populations. Scalloped hammerhead, white, and thresher sharks are each estimated to have declined by over 75% in the past 15 years. Closed-area models highlight priority areas for shark conservation, and the need to consider effort reallocation and site selection if marine reserves are to benefit multiple threatened species.

@article{doi101126science1079777,
    author = "Baum, Julia K. and Myers, Ransom A. and Kehler, Daniel G. and Worm, Boris and Harley, Shelton J. and Doherty, Penny A.",
    title = "Collapse and Conservation of Shark Populations in the Northwest Atlantic",
    year = "2003",
    journal = "Science",
    abstract = "Overexploitation threatens the future of many large vertebrates. In the ocean, tunas and sea turtles are current conservation concerns because of this intense pressure. The status of most shark species, in contrast, remains uncertain. Using the largest data set in the Northwest Atlantic, we show rapid large declines in large coastal and oceanic shark populations. Scalloped hammerhead, white, and thresher sharks are each estimated to have declined by over 75\% in the past 15 years. Closed-area models highlight priority areas for shark conservation, and the need to consider effort reallocation and site selection if marine reserves are to benefit multiple threatened species.",
    url = "https://doi.org/10.1126/science.1079777",
    doi = "10.1126/science.1079777",
    openalex = "W2110899929",
    references = "openalexw570265017"
}

Abstract Historical abundances of many large marine vertebrates were tremendously greater than today. However, while pelagic sharks are known to have declined rapidly in the northwest Atlantic in recent years, there, as elsewhere, little is known about the former natural abundances of these species. Here, we compare initial (1950s) and recent (late‐1990s) standardized catch rates of pelagic sharks in the Gulf of Mexico, the area where methods of exploitation between these two periods were most comparable. We estimate that oceanic whitetip and silky sharks, formerly the most commonly caught shark species, have declined by over 99 and 90%, respectively. That the former prevalence of oceanic whitetip sharks in this ecosystem is unrecognized today is clear evidence of shifting baselines. Our analysis provides the missing baseline for pelagic sharks in the Gulf of Mexico that is needed for the rational management and restoration of these species.

@article{doi101111j14610248200300564x,
    author = "Baum, Julia K. and Myers, Ransom A.",
    title = "Shifting baselines and the decline of pelagic sharks in the Gulf of Mexico",
    year = "2004",
    journal = "Ecology Letters",
    abstract = "Abstract Historical abundances of many large marine vertebrates were tremendously greater than today. However, while pelagic sharks are known to have declined rapidly in the northwest Atlantic in recent years, there, as elsewhere, little is known about the former natural abundances of these species. Here, we compare initial (1950s) and recent (late‐1990s) standardized catch rates of pelagic sharks in the Gulf of Mexico, the area where methods of exploitation between these two periods were most comparable. We estimate that oceanic whitetip and silky sharks, formerly the most commonly caught shark species, have declined by over 99 and 90\%, respectively. That the former prevalence of oceanic whitetip sharks in this ecosystem is unrecognized today is clear evidence of shifting baselines. Our analysis provides the missing baseline for pelagic sharks in the Gulf of Mexico that is needed for the rational management and restoration of these species.",
    url = "https://doi.org/10.1111/j.1461-0248.2003.00564.x",
    doi = "10.1111/j.1461-0248.2003.00564.x",
    openalex = "W2149474140",
    references = "openalexw570265017"
}

The morphology of the jaw suspension and jaw protrusion mechanism in lamniform sharks is described and mapped onto a cladogram to investigate how changes in jaw suspension and protrusion have evolved. This has revealed that several evolutionary modifications in the musculoskeletal apparatus of the jaws have taken place among lamniform sharks. Galeomorph sharks (Carcharhiniformes, Lamniformes, Orectolobiformes, and Heterodontiformes) have paired ethmopalatine ligaments connecting the ethmoid process of the upper jaw to the ethmoid region of the cranium. Basal lamniform sharks also acquired a novel single palatonasal ligament connecting the symphysis of the upper jaw to the cranium mid-ventral to the nasal capsule. Sharks in the family Lamnidae subsequently lost the original paired ethmopalatine ligament while retaining the novel palatonasal ligament. Thus, basal lamniform taxa (Mitsukurina owstoni, Carcharius taurus, Alopias vulpinnis) have increased ligamentous support of the lateral region of the upper jaw while derived species (Lamnidae) have lost this lateral support but gained anterior support. In previous studies the morphology of the jaw suspension has been shown to play a major role in the mechanism of upper jaw protrusion in elasmobranchs. The preorbitalis is the primary muscle effecting upper jaw protrusion in squalean (sister group to galeomorphs) and carcharhiniform (sister group to lamniforms) sharks. The preorbitalis originates from the quadratomandibularis muscle and inserts onto the nasal capsule in squalean and carcharhiniform sharks. Carcharhiniform sharks have evolved a subdivided preorbitalis muscle with the new division inserting near the ethmoid process of the palatoquadrate (upper jaw). Alopid sharks have also independently evolved a partially subdivided preorbitalis with the new division inserting at the base of the ethmoid process and surrounding connective tissue. Lamnid sharks have retained the two preorbitalis divisions but have modified both of the insertion points. The original ventral preorbitalis division now inserts onto the connective tissue surrounding the mid-region of the upper jaw, while the new dorsal preorbitalis division inserts onto the surrounding connective tissue and skin at a more posterior position on the upper jaw. The retractor muscle of the jaws, the levator hyomandibularis, has also been modified during the evolution of lamniform sharks. In most sharks, including basal lamniforms, the levator hyomandibularis inserts onto the hyomandibula and functions to retract the jaws after protrusion. In alopid and lamnid sharks the levator hyomandibularis inserts primarily onto the upper and lower jaws around the jaw joint and is a more direct route for retracting the jaws. Thus, there has been at least one instance of character loss (ethmopalatine ligament), acquisition (palatonasal ligament), subdivision (preorbitalis), and modification (ventral preorbitalis, dorsal preorbitalis, and levator hyomandibularis) in the ligaments and muscles associated with the jaw suspension and jaw protrusion mechanism in lamniform sharks. While derived lamniform sharks (Lamna nasus, Carcharodon carcharius, and Isurus oxyrinchus) lost the ancestral passive lateral support of the ethmoid articulation of the upper jaw, they simultaneously acquired muscular support by way of the levator hyomandibularis, which provides a dynamic mechanism for lateral support. The evolution of multiple divisions of preorbitalis insertions onto the palatoquadrate and modification of the levator hyomandibularis insertion directly onto the jaws provides an active mechanism for multiple protractions and retractions of the upper jaw, which is advantageous in those sharks that gouge or saw pieces from large oversized prey items.

@article{doi101002jmor10342,
    author = "Wilga, Cheryl D.",
    title = "Morphology and evolution of the jaw suspension in lamniform sharks",
    year = "2005",
    journal = "Journal of Morphology",
    abstract = "The morphology of the jaw suspension and jaw protrusion mechanism in lamniform sharks is described and mapped onto a cladogram to investigate how changes in jaw suspension and protrusion have evolved. This has revealed that several evolutionary modifications in the musculoskeletal apparatus of the jaws have taken place among lamniform sharks. Galeomorph sharks (Carcharhiniformes, Lamniformes, Orectolobiformes, and Heterodontiformes) have paired ethmopalatine ligaments connecting the ethmoid process of the upper jaw to the ethmoid region of the cranium. Basal lamniform sharks also acquired a novel single palatonasal ligament connecting the symphysis of the upper jaw to the cranium mid-ventral to the nasal capsule. Sharks in the family Lamnidae subsequently lost the original paired ethmopalatine ligament while retaining the novel palatonasal ligament. Thus, basal lamniform taxa (Mitsukurina owstoni, Carcharius taurus, Alopias vulpinnis) have increased ligamentous support of the lateral region of the upper jaw while derived species (Lamnidae) have lost this lateral support but gained anterior support. In previous studies the morphology of the jaw suspension has been shown to play a major role in the mechanism of upper jaw protrusion in elasmobranchs. The preorbitalis is the primary muscle effecting upper jaw protrusion in squalean (sister group to galeomorphs) and carcharhiniform (sister group to lamniforms) sharks. The preorbitalis originates from the quadratomandibularis muscle and inserts onto the nasal capsule in squalean and carcharhiniform sharks. Carcharhiniform sharks have evolved a subdivided preorbitalis muscle with the new division inserting near the ethmoid process of the palatoquadrate (upper jaw). Alopid sharks have also independently evolved a partially subdivided preorbitalis with the new division inserting at the base of the ethmoid process and surrounding connective tissue. Lamnid sharks have retained the two preorbitalis divisions but have modified both of the insertion points. The original ventral preorbitalis division now inserts onto the connective tissue surrounding the mid-region of the upper jaw, while the new dorsal preorbitalis division inserts onto the surrounding connective tissue and skin at a more posterior position on the upper jaw. The retractor muscle of the jaws, the levator hyomandibularis, has also been modified during the evolution of lamniform sharks. In most sharks, including basal lamniforms, the levator hyomandibularis inserts onto the hyomandibula and functions to retract the jaws after protrusion. In alopid and lamnid sharks the levator hyomandibularis inserts primarily onto the upper and lower jaws around the jaw joint and is a more direct route for retracting the jaws. Thus, there has been at least one instance of character loss (ethmopalatine ligament), acquisition (palatonasal ligament), subdivision (preorbitalis), and modification (ventral preorbitalis, dorsal preorbitalis, and levator hyomandibularis) in the ligaments and muscles associated with the jaw suspension and jaw protrusion mechanism in lamniform sharks. While derived lamniform sharks (Lamna nasus, Carcharodon carcharius, and Isurus oxyrinchus) lost the ancestral passive lateral support of the ethmoid articulation of the upper jaw, they simultaneously acquired muscular support by way of the levator hyomandibularis, which provides a dynamic mechanism for lateral support. The evolution of multiple divisions of preorbitalis insertions onto the palatoquadrate and modification of the levator hyomandibularis insertion directly onto the jaws provides an active mechanism for multiple protractions and retractions of the upper jaw, which is advantageous in those sharks that gouge or saw pieces from large oversized prey items.",
    url = "https://doi.org/10.1002/jmor.10342",
    doi = "10.1002/jmor.10342",
    openalex = "W2102002192",
    references = "doi101016b9780126709506500035, doi101016b9780126709506500047, doi101023a1018471324332, doi101093bioscience1610752a, doi101093icb172303, doi101093oso97801985404720010001, doi1023071445465, doi1023071445562, doi105962bhltitle20311, openalexw3211386673, openalexw570265017, openalexw596245786"
}

between 1997 and 2003, there were 2088 natural predations by white sharks (carcharodon carcharias) on cape fur seals (arctocephalus pusillus pusillus) and 121 strikes on towed seal-shaped decoys were documented from observation vessels at seal island, south africa. white sharks at seal island appear to selectively target lone, incoming young of the year cape fur seals at or near the surface. most attacks lasted <1 min and consisted of a single breach, with predatory success rate decreasing rapidly with increasing duration and number of subsequent breaches. a white shark predatory ethogram, composed of four phases and 20 behavioural units, is presented, including four varieties of initial strike and 11 subsequent behaviour units not previously defined in the literature. behaviour units scored from 210 predatory attacks revealed that, for both successful and unsuccessful attacks, polaris breach was the most commonly employed initial strike, while surface lunge was the most frequent second event, closely followed by lateral snap. examination of video footage, still images, and tooth impressions in decoys indicated that white sharks at seal island bite prey obliquely using their anterolateral teeth via a sudden lateral snap of the jaws and not perpendicularly with their anterior teeth, as previously supposed. analysis of white shark upper tooth morphology and spacing suggest the reversed intermediate teeth of white sharks occur at the strongest part of the jaw and produce the largest wound. white shark predatory success at seal island is greatest (55%) within one hour of sunrise and decreases rapidly with increasing ambient light; the sharks cease active predation on seals when success rate drops to ±40%; this is the first evidence of cessation of foraging at unproductive times by any predatory fish. at seal island, white shark predatory success is significantly lower at locations where frequency of predation is highest, suggesting that white sharks may launch suboptimal strikes in areas of greatest intraspecific competition; this is the first evidence of social influence on predation in any elasmobranch. idiosyncratic predatory behaviours and elevated success rates of known individual white sharks at seal island suggest some degree of trial-and-error learning. a hypothetical decision tree is proposed that models predatory behaviour of white sharks attacking cape fur seals at the surface.

@article{doi101017s002531540501218x,
    author = "Martin, Ralph and Hammerschlag, Neil and Collier, Ralph S. and Fallows, Chris",
    title = "predatory behaviour of white sharks (carcharodon carcharias) at seal island, south africa",
    year = "2005",
    journal = "Journal of the Marine Biological Association of the United Kingdom",
    abstract = "between 1997 and 2003, there were 2088 natural predations by white sharks (carcharodon carcharias) on cape fur seals (arctocephalus pusillus pusillus) and 121 strikes on towed seal-shaped decoys were documented from observation vessels at seal island, south africa. white sharks at seal island appear to selectively target lone, incoming young of the year cape fur seals at or near the surface. most attacks lasted <1 min and consisted of a single breach, with predatory success rate decreasing rapidly with increasing duration and number of subsequent breaches. a white shark predatory ethogram, composed of four phases and 20 behavioural units, is presented, including four varieties of initial strike and 11 subsequent behaviour units not previously defined in the literature. behaviour units scored from 210 predatory attacks revealed that, for both successful and unsuccessful attacks, polaris breach was the most commonly employed initial strike, while surface lunge was the most frequent second event, closely followed by lateral snap. examination of video footage, still images, and tooth impressions in decoys indicated that white sharks at seal island bite prey obliquely using their anterolateral teeth via a sudden lateral snap of the jaws and not perpendicularly with their anterior teeth, as previously supposed. analysis of white shark upper tooth morphology and spacing suggest the reversed intermediate teeth of white sharks occur at the strongest part of the jaw and produce the largest wound. white shark predatory success at seal island is greatest (55\%) within one hour of sunrise and decreases rapidly with increasing ambient light; the sharks cease active predation on seals when success rate drops to ±40\%; this is the first evidence of cessation of foraging at unproductive times by any predatory fish. at seal island, white shark predatory success is significantly lower at locations where frequency of predation is highest, suggesting that white sharks may launch suboptimal strikes in areas of greatest intraspecific competition; this is the first evidence of social influence on predation in any elasmobranch. idiosyncratic predatory behaviours and elevated success rates of known individual white sharks at seal island suggest some degree of trial-and-error learning. a hypothetical decision tree is proposed that models predatory behaviour of white sharks attacking cape fur seals at the surface.",
    url = "https://doi.org/10.1017/s002531540501218x",
    doi = "10.1017/s002531540501218x",
    openalex = "W2143630245",
    references = "doi101002jmor1073, doi101007bf00539785, doi101007s002270000489, doi101016b9780124150317500173, doi101016b9780124150317500288, doi101016s0003347289800302, doi101016s1095643301003336, doi10103830959, doi1023071445310, doi105281zenodo16136060, openalexw3217546838, openalexw570265017"
}

The large-scale spatial dynamics and population structure of marine top predators are poorly known. We present electronic tag and photographic identification data showing a complex suite of behavioral patterns in white sharks. These include coastal return migrations and the fastest known transoceanic return migration among swimming fauna, which provide direct evidence of a link between widely separated populations in South Africa and Australia. Transoceanic return migration involved a return to the original capture location, dives to depths of 980 meters, and the tolerance of water temperatures as low as 3.4 degrees C. These findings contradict previous ideas that female white sharks do not make transoceanic migrations, and they suggest natal homing behavior.

@article{doi101126science1114898,
    author = "Bonfil, Ramón and Meÿer, Michael A. and Scholl, Michael C. and Johnson, Ryan and O’Brien, Shannon M. and Oosthuizen, Herman and Swanson, Stephan and Kotze, Deon and Paterson, Michael J.",
    title = "Transoceanic Migration, Spatial Dynamics, and Population Linkages of White Sharks",
    year = "2005",
    journal = "Science",
    abstract = "The large-scale spatial dynamics and population structure of marine top predators are poorly known. We present electronic tag and photographic identification data showing a complex suite of behavioral patterns in white sharks. These include coastal return migrations and the fastest known transoceanic return migration among swimming fauna, which provide direct evidence of a link between widely separated populations in South Africa and Australia. Transoceanic return migration involved a return to the original capture location, dives to depths of 980 meters, and the tolerance of water temperatures as low as 3.4 degrees C. These findings contradict previous ideas that female white sharks do not make transoceanic migrations, and they suggest natal homing behavior.",
    url = "https://doi.org/10.1126/science.1114898",
    doi = "10.1126/science.1114898",
    openalex = "W2104068398",
    references = "openalexw570265017"
}

Although many coastal shark species have widespread distributions, the genetic relatedness of worldwide populations has been examined for few species. The blacktip shark, (Carcharhinus limbatus), inhabits tropical and subtropical coastal waters throughout the world. In this study, we examined the genetic relationships of blacktip shark populations (n = 364 sharks) throughout the majority of the species' range using the entire mitochondrial control region (1067-1070 nucleotides). Two geographically distinct maternal lineages (western Atlantic, Gulf of Mexico, and Caribbean Sea clades, and eastern Atlantic, Indian, and Pacific Ocean clades) were identified and shallow population structure was detected throughout their geographic ranges. These findings indicate that a major population subdivision exists across the Atlantic Ocean, but not the Pacific Ocean. The historical dispersal of this widespread, coastal species may have been interrupted by the rise of the Isthmus of Panama. This scenario implies historical dispersal across the Pacific Ocean (supported by the recovery of the same common haplotype from the Philippines, Hawaii, and the Gulf of California reflecting recent/contemporary dispersal abilities) and an oceanic barrier to recent migration across the Atlantic. Genetic structure within the eastern Atlantic/Indo-Pacific (Phi(ST) = 0.612, P < 0.001) supports maternal philopatry throughout this area, expanding previous western Atlantic findings. Eastern Atlantic/Indo-Pacific C. limbatus control region haplotypes were paraphyletic to Carcharhinus tilstoni haplotypes in our maximum-parsimony analysis. The greater divergence of western Atlantic C. limbatus than C. tilstoni from eastern Atlantic/Indo-Pacific C. limbatus reflects the taxonomic uncertainty of western Atlantic C. limbatus.

@article{doi101111j1365294x200603036x,
    author = "Keeney, Devon B. and Heist, Edward J.",
    title = "Worldwide phylogeography of the blacktip shark (Carcharhinus limbatus) inferred from mitochondrial DNA reveals isolation of western Atlantic populations coupled with recent Pacific dispersal",
    year = "2006",
    journal = "Molecular Ecology",
    abstract = "Although many coastal shark species have widespread distributions, the genetic relatedness of worldwide populations has been examined for few species. The blacktip shark, (Carcharhinus limbatus), inhabits tropical and subtropical coastal waters throughout the world. In this study, we examined the genetic relationships of blacktip shark populations (n = 364 sharks) throughout the majority of the species' range using the entire mitochondrial control region (1067-1070 nucleotides). Two geographically distinct maternal lineages (western Atlantic, Gulf of Mexico, and Caribbean Sea clades, and eastern Atlantic, Indian, and Pacific Ocean clades) were identified and shallow population structure was detected throughout their geographic ranges. These findings indicate that a major population subdivision exists across the Atlantic Ocean, but not the Pacific Ocean. The historical dispersal of this widespread, coastal species may have been interrupted by the rise of the Isthmus of Panama. This scenario implies historical dispersal across the Pacific Ocean (supported by the recovery of the same common haplotype from the Philippines, Hawaii, and the Gulf of California reflecting recent/contemporary dispersal abilities) and an oceanic barrier to recent migration across the Atlantic. Genetic structure within the eastern Atlantic/Indo-Pacific (Phi(ST) = 0.612, P < 0.001) supports maternal philopatry throughout this area, expanding previous western Atlantic findings. Eastern Atlantic/Indo-Pacific C. limbatus control region haplotypes were paraphyletic to Carcharhinus tilstoni haplotypes in our maximum-parsimony analysis. The greater divergence of western Atlantic C. limbatus than C. tilstoni from eastern Atlantic/Indo-Pacific C. limbatus reflects the taxonomic uncertainty of western Atlantic C. limbatus.",
    url = "https://doi.org/10.1111/j.1365-294x.2006.03036.x",
    doi = "10.1111/j.1365-294x.2006.03036.x",
    openalex = "W2096371932",
    references = "openalexw2900647185"
}

The Neoselachii are a monophyletic group including all of the extant sharks and rays. They underwent rapid diversification throughout the Jurassic and Cretaceous, going from low-diversity assemblages of members of extinct orders in the Late Triassic to diverse assemblages containing representatives of most extant clades by the end of the Cretaceous. The known fossil record of Mesozoic neoselachians is composed largely of isolated teeth, with articulated skeletal remains being known from a limited number of sites. The small tooth size of a large proportion of neoselachians, including almost all taxa in existence prior to the mid Cretaceous, led to very poor representation in older publications. Their state of knowledge has improved dramatically since 1970 with the increased use of bulk sampling for isolated dental remains. Despite this, the high proportion of Lazarus taxa from some stages suggests that the state of knowledge is still intermittent. Increase in assemblage diversity throughout the Jurassic and Cretaceous suggests that radiation events resulted in real and dramatic increases in diversity, and that the perceived diversification is not an artifact of poor knowledge. Cladogenesis inferred from the fossil record typically compares more favorably with divergence predicted from molecular analysis, where Batoidea form a discrete basal clade, than with divergence predicted from morphological analysis, where Batoidea are considered a derived crown group within the Squalea. The timing of diversification events is discussed in light of the known fossil record, cladistically generated divergence times, and the paleoenvironmental distribution of faunas.

@article{doi101666040691,
    author = "Underwood, Charlie J.",
    title = "Diversification of the Neoselachii (Chondrichthyes) during the Jurassic and Cretaceous",
    year = "2006",
    journal = "Paleobiology",
    abstract = "The Neoselachii are a monophyletic group including all of the extant sharks and rays. They underwent rapid diversification throughout the Jurassic and Cretaceous, going from low-diversity assemblages of members of extinct orders in the Late Triassic to diverse assemblages containing representatives of most extant clades by the end of the Cretaceous. The known fossil record of Mesozoic neoselachians is composed largely of isolated teeth, with articulated skeletal remains being known from a limited number of sites. The small tooth size of a large proportion of neoselachians, including almost all taxa in existence prior to the mid Cretaceous, led to very poor representation in older publications. Their state of knowledge has improved dramatically since 1970 with the increased use of bulk sampling for isolated dental remains. Despite this, the high proportion of Lazarus taxa from some stages suggests that the state of knowledge is still intermittent. Increase in assemblage diversity throughout the Jurassic and Cretaceous suggests that radiation events resulted in real and dramatic increases in diversity, and that the perceived diversification is not an artifact of poor knowledge. Cladogenesis inferred from the fossil record typically compares more favorably with divergence predicted from molecular analysis, where Batoidea form a discrete basal clade, than with divergence predicted from morphological analysis, where Batoidea are considered a derived crown group within the Squalea. The timing of diversification events is discussed in light of the known fossil record, cladistically generated divergence times, and the paleoenvironmental distribution of faunas.",
    url = "https://doi.org/10.1666/04069.1",
    doi = "10.1666/04069.1",
    openalex = "W2167368338",
    references = "doi105962bhltitle4275"
}

The foraging ecology of the school shark Galeorhinus galeus was studied in Anegada Bay, Argentina, during the seasonal occurrence of this species in Argentinean waters (October to April) from 1998 to 2001. Of the 408 individuals examined, 168 (41.2%) had food remains in their stomachs. The proportion of individuals with food remains was negatively correlated with total length. In general, the diet was composed mainly of teleosts (98.5% IRI [index of relative importance]), with invertebrates and chondrichthyans as minor prey. The diet varied ontogenetically and seasonally. Juveniles and adults differed in their consumption of invertebrates, with juveniles preying more on benthic invertebrates, mainly the octopus Octopus tehuelchus, and adults on squid. From December to February, adults preyed mainly on benthic teleosts (almost exclusively the Atlantic midshipman Porichthys porosissimus), while from March to April the consumption of squid increased. A comparison of numbers of prey in stomachs with abundance of prey in the environment in March and April showed that, in these months, juveniles selected invertebrates and demersal teleosts and avoided pelagic teleosts and chondricthyan prey, and adults selected squid and avoided pelagic teleosts. This indicates that, during this period, G. galeus is not an opportunistic predator. The mean size of prey increased with increasing shark length, but even large sharks consumed small prey. All shark sizes consumed prey fragments that were significantly larger than other prey consumed whole. This indicates that G. galeus is able to overcome gape limitation by mutilating prey, and that the ontogenetic diet shift was not due to a change in the ability to seize prey.

@article{doi103354meps315259,
    author = "Lucifora, Luis O. and García, VB and Menni, R.C and Escalante, AH",
    title = "Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus",
    year = "2006",
    journal = "Marine Ecology Progress Series",
    abstract = "The foraging ecology of the school shark Galeorhinus galeus was studied in Anegada Bay, Argentina, during the seasonal occurrence of this species in Argentinean waters (October to April) from 1998 to 2001. Of the 408 individuals examined, 168 (41.2\%) had food remains in their stomachs. The proportion of individuals with food remains was negatively correlated with total length. In general, the diet was composed mainly of teleosts (98.5\% IRI [index of relative importance]), with invertebrates and chondrichthyans as minor prey. The diet varied ontogenetically and seasonally. Juveniles and adults differed in their consumption of invertebrates, with juveniles preying more on benthic invertebrates, mainly the octopus Octopus tehuelchus, and adults on squid. From December to February, adults preyed mainly on benthic teleosts (almost exclusively the Atlantic midshipman Porichthys porosissimus), while from March to April the consumption of squid increased. A comparison of numbers of prey in stomachs with abundance of prey in the environment in March and April showed that, in these months, juveniles selected invertebrates and demersal teleosts and avoided pelagic teleosts and chondricthyan prey, and adults selected squid and avoided pelagic teleosts. This indicates that, during this period, G. galeus is not an opportunistic predator. The mean size of prey increased with increasing shark length, but even large sharks consumed small prey. All shark sizes consumed prey fragments that were significantly larger than other prey consumed whole. This indicates that G. galeus is able to overcome gape limitation by mutilating prey, and that the ontogenetic diet shift was not due to a change in the ability to seize prey.",
    url = "https://doi.org/10.3354/meps315259",
    doi = "10.3354/meps315259",
    openalex = "W2160832272",
    references = "doi101023a1007649900712"
}

The teeth of white-spotted bamboo sharks (Chiloscyllium plagiosum) are used to clutch soft-bodied prey and crush hard prey; however, the dual function is not evident from tooth morphology alone. Teeth exhibit characteristics that are in agreement with a clutching-type tooth morphology that is well suited for grasping and holding soft-bodied prey, but not for crushing hard prey. The dual role of this single tooth morphology is facilitated by features of the dental ligament and jaw joint. Tooth attachment is flexible and elastic, allowing movement in both sagittal and frontal planes. During prey capture spike-like tooth cusps pierce the flesh of soft prey, thereby preventing escape. When processing prey harder than the teeth can pierce the teeth passively depress, rotating inward towards the oral cavity such that the broader labial faces of the teeth are nearly parallel to the surface of the jaws and form a crushing surface. Movement into the depressed position increases the tooth surface area contacting prey and decreases the total stress applied to the tooth, thereby decreasing the risk of structural failure. This action is aided by a jaw joint that is ventrally offset from the occlusal planes of the jaws. The offset joint position allows many teeth to contact prey simultaneously and orients force vectors at contact points between the jaws and prey in a manner that shears or rolls prey between the jaws during a bite, thus, aiding in processing while reducing forward slip of hard prey from the mouth. Together the teeth, dental ligament, and jaws form an integrated system that may be beneficial to the feeding ecology of C. plagiosum, allowing for a diet that includes prey of varying hardness and elusiveness.

@article{doi101002jmor10530,
    author = "Ramsay, Jason B. and Wilga, Cheryl D.",
    title = "Morphology and mechanics of the teeth and jaws of white‐spotted bamboo sharks (Chiloscyllium plagiosum)",
    year = "2007",
    journal = "Journal of Morphology",
    abstract = "The teeth of white-spotted bamboo sharks (Chiloscyllium plagiosum) are used to clutch soft-bodied prey and crush hard prey; however, the dual function is not evident from tooth morphology alone. Teeth exhibit characteristics that are in agreement with a clutching-type tooth morphology that is well suited for grasping and holding soft-bodied prey, but not for crushing hard prey. The dual role of this single tooth morphology is facilitated by features of the dental ligament and jaw joint. Tooth attachment is flexible and elastic, allowing movement in both sagittal and frontal planes. During prey capture spike-like tooth cusps pierce the flesh of soft prey, thereby preventing escape. When processing prey harder than the teeth can pierce the teeth passively depress, rotating inward towards the oral cavity such that the broader labial faces of the teeth are nearly parallel to the surface of the jaws and form a crushing surface. Movement into the depressed position increases the tooth surface area contacting prey and decreases the total stress applied to the tooth, thereby decreasing the risk of structural failure. This action is aided by a jaw joint that is ventrally offset from the occlusal planes of the jaws. The offset joint position allows many teeth to contact prey simultaneously and orients force vectors at contact points between the jaws and prey in a manner that shears or rolls prey between the jaws during a bite, thus, aiding in processing while reducing forward slip of hard prey from the mouth. Together the teeth, dental ligament, and jaws form an integrated system that may be beneficial to the feeding ecology of C. plagiosum, allowing for a diet that includes prey of varying hardness and elusiveness.",
    url = "https://doi.org/10.1002/jmor.10530",
    doi = "10.1002/jmor.10530",
    openalex = "W2133211355",
    references = "doi101002jmor10342"
}

Parthenogenesis has been documented in all major jawed vertebrate lineages except mammals and cartilaginous fishes (class Chondrichthyes: sharks, batoids and chimeras). Reports of captive female sharks giving birth despite being held in the extended absence of males have generally been ascribed to prior matings coupled with long-term sperm storage by the females. Here, we provide the first genetic evidence for chondrichthyan parthenogenesis, involving a hammerhead shark (Sphyrna tiburo). This finding also broadens the known occurrence of a specific type of asexual development (automictic parthenogenesis) among vertebrates, extending recently raised concerns about the potential negative effect of this type of facultative parthenogenesis on the genetic diversity of threatened vertebrate species.

@article{doi101098rsbl20070189,
    author = "Chapman, Demian D. and Shivji, Mahmood S. and Louis, Ed and Sommer, Julie A. and Fletcher, Hugh and Prodöhl, Paulo A.",
    title = "Virgin birth in a hammerhead shark",
    year = "2007",
    journal = "Biology Letters",
    abstract = "Parthenogenesis has been documented in all major jawed vertebrate lineages except mammals and cartilaginous fishes (class Chondrichthyes: sharks, batoids and chimeras). Reports of captive female sharks giving birth despite being held in the extended absence of males have generally been ascribed to prior matings coupled with long-term sperm storage by the females. Here, we provide the first genetic evidence for chondrichthyan parthenogenesis, involving a hammerhead shark (Sphyrna tiburo). This finding also broadens the known occurrence of a specific type of asexual development (automictic parthenogenesis) among vertebrates, extending recently raised concerns about the potential negative effect of this type of facultative parthenogenesis on the genetic diversity of threatened vertebrate species.",
    url = "https://doi.org/10.1098/rsbl.2007.0189",
    doi = "10.1098/rsbl.2007.0189",
    openalex = "W2108691006"
}

We compared life-history traits and extinction risk of chondrichthyans (sharks, rays and chimaeras), a group of high conservation concern, from the three major marine habitats (continental shelves, open ocean and deep sea), controlling for phylogenetic correlation. Deep-water chondrichthyans had a higher age at maturity and longevity, and a lower growth completion rate than shallow-water species. The average fishing mortality needed to drive a deep-water chondrichthyan species to extinction (Fextinct) was 38-58% of that estimated for oceanic and continental shelf species, respectively. Mean values of Fextinct were 0.149, 0.250 and 0.368 for deep-water, oceanic and continental shelf species, respectively. Reproductive mode was an important determinant of extinction risk, while body size had a weak effect on extinction risk. As extinction risk was highly correlated with phylogeny, the loss of species will be accompanied by a loss of phylogenetic diversity. Conservation priority should not be restricted to large species, as is usually suggested, since many small species, like those inhabiting the deep ocean, are also highly vulnerable to extinction. Fishing mortality of deep-water chondrichthyans already exploited should be minimized, and new deep-water fisheries affecting chondrichthyans should be prevented.

@article{doi101098rspb20071295,
    author = "García, Verónica B. and Lucifora, Luis O. and Myers, Ransom A.",
    title = "The importance of habitat and life history to extinction risk in sharks, skates, rays and chimaeras",
    year = "2007",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "We compared life-history traits and extinction risk of chondrichthyans (sharks, rays and chimaeras), a group of high conservation concern, from the three major marine habitats (continental shelves, open ocean and deep sea), controlling for phylogenetic correlation. Deep-water chondrichthyans had a higher age at maturity and longevity, and a lower growth completion rate than shallow-water species. The average fishing mortality needed to drive a deep-water chondrichthyan species to extinction (Fextinct) was 38-58\% of that estimated for oceanic and continental shelf species, respectively. Mean values of Fextinct were 0.149, 0.250 and 0.368 for deep-water, oceanic and continental shelf species, respectively. Reproductive mode was an important determinant of extinction risk, while body size had a weak effect on extinction risk. As extinction risk was highly correlated with phylogeny, the loss of species will be accompanied by a loss of phylogenetic diversity. Conservation priority should not be restricted to large species, as is usually suggested, since many small species, like those inhabiting the deep ocean, are also highly vulnerable to extinction. Fishing mortality of deep-water chondrichthyans already exploited should be minimized, and new deep-water fisheries affecting chondrichthyans should be prevented.",
    url = "https://doi.org/10.1098/rspb.2007.1295",
    doi = "10.1098/rspb.2007.1295",
    openalex = "W2158529059",
    references = "doi101007s1064100521365, doi1023071447035, openalexw1511461941, openalexw3211386673"
}

The widespread variation in brain size and complexity that is evident in sharks and holocephalans is related to both phylogeny and ecology. Relative brain size (expressed as encephalization quotients) and the relative development of the five major brain areas (the telencephalon, diencephalon, mesencephalon, cerebellum, and medulla) was assessed for over 40 species from 20 families that represent a range of different lifestyles and occupy a number of habitats. In addition, an index (1-5) quantifying structural complexity of the cerebellum was created based on length, number, and depth of folds. Although the variation in brain size, morphology, and complexity is due in part to phylogeny, as basal groups have smaller brains, less structural hypertrophy, and lower foliation indices, there is also substantial variation within and across clades that does not reflect phylogenetic relationships. Ecological correlations, with the relative development of different brain areas as well as the complexity of the cerebellar corpus, are supported by cluster analysis and are suggestive of a range of 'cerebrotypes'. These correlations suggest that relative brain development reflects the dimensionality of the environment and/or agile prey capture in addition to phylogeny.

@article{doi101159000100037,
    author = "Yopak, Kara E. and Lisney, Thomas J. and Collin, Shaun P. and Montgomery, John C.",
    title = "Variation in Brain Organization and Cerebellar Foliation in Chondrichthyans: Sharks and Holocephalans",
    year = "2007",
    journal = "Brain Behavior and Evolution",
    abstract = "The widespread variation in brain size and complexity that is evident in sharks and holocephalans is related to both phylogeny and ecology. Relative brain size (expressed as encephalization quotients) and the relative development of the five major brain areas (the telencephalon, diencephalon, mesencephalon, cerebellum, and medulla) was assessed for over 40 species from 20 families that represent a range of different lifestyles and occupy a number of habitats. In addition, an index (1-5) quantifying structural complexity of the cerebellum was created based on length, number, and depth of folds. Although the variation in brain size, morphology, and complexity is due in part to phylogeny, as basal groups have smaller brains, less structural hypertrophy, and lower foliation indices, there is also substantial variation within and across clades that does not reflect phylogenetic relationships. Ecological correlations, with the relative development of different brain areas as well as the complexity of the cerebellar corpus, are supported by cluster analysis and are suggestive of a range of 'cerebrotypes'. These correlations suggest that relative brain development reflects the dimensionality of the environment and/or agile prey capture in addition to phylogeny.",
    url = "https://doi.org/10.1159/000100037",
    doi = "10.1159/000100037",
    openalex = "W2089378501",
    references = "doi1010160025556471900514, doi101016b9780126709506500035, doi101086284325, doi101093sysbio41118, doi1010970000505319361100000044, doi101113jphysiol1969sp008820, doi101523jneurosci1405032081994, doi1023071442530, doi1023072407154, doi105860choice295104, openalexw143324445, openalexw3211386673, openalexw570265017"
}

The concepts of platytrabia/platybasia and tropibasia/tropitrabia in gnathostomes are reviewed. The terms platytrabia and tropitrabia refer to developmental states of the embryonic trabecular cartilages that can be determined only by ontogenetic studies. The terms platybasia and tropibasia originally had this meaning, but have subsequently taken on additional descriptive connotations involving morphological features in the prechordal part of the adult chondrocranium. However, platybasia and tropibasia are not synonymous with platytrabia and tropitrabia. In gnathostomes, platytrabia usually gives rise to a platybasic adult condition (but not invariably; e.g., Lepisosteus), and tropitrabia usually gives rise to the tropibasic condition (modern elasmobranchs may be an exception). Thus, ontogeny does not provide an absolute guide to the adult condition, nor does adult morphology provide an accurate means to assess the prior ontogenetic condition in gnathostomes. Platybasia and tropibasia are regarded here as useful morphological terms that can be applied to fossils or to extant forms for which ontogenetic data are not available (although it may still be possible to reach some ontogenetic conclusions, based on morphological observations).A well-preserved but disarticulated fossil symmoriiform shark braincase from the Pennsylvanian of Arkansas is described under the informal generic designation “Cobelodus”, using digital reconstructions made from a high-resolution computerized-tomography (CT) scan. The braincase is morphologically tropibasic and clearly represents a departure from the common platybasic pattern found in elasmobranchs (e.g., Tamiobatis, Cladodoides, Orthacanthus).The contribution made by the embryonic polar cartilage in “Cobelodus” was probably extensive (unlike in modern gnathostomes), as in the platybasic Paleozoic shark Cladodoides. Thus, tropibasia in “Cobelodus” seems to be superimposed on an already-specialized pattern of cranial morphology found in some early platybasic elasmobranchs. The basicranial arterial circuit in “Cobelodus” was highly modified, and its internal carotids could not have communicated with the cranial cavity via the bucco-hypophyseal chamber as in other elasmobranchs. Internal carotids either were absent or met the efferent pseudobranchials within the orbit before the combined vessel entered the cranial cavity via the orbital cartilage, but the arrangement was certainly not osteichthyan-like (where the combined internal carotid/efferent pseudobranchial arteries pass through the basisphenoid pillar).“Cobelodus” and many other Paleozoic sharks possessed a postorbital palatoquadrate articulation (possibly strengthened by ligaments above the articulation in “Cobelodus”), on cartilage presumably formed in the embryonic lateral commissure. This arrangement differs from that in amphistylic hexanchiform sharks, where the lateral commissure is absent and there is no postorbital arcade; the postorbital articulation is located instead on the primary postorbital process (an outgrowth of the supraorbital shelf). Hexanchiforms are the only extant elasmobranchs with a postorbital articulation, but do not occupy a basal position in modern morphological and molecular phylogenetic analyses. Amphistyly in hexanchiforms is therefore viewed as a derived state rather than a highly conserved feature.No hyomandibular facet has been identified in “Cobelodus”, suggesting that its epihyal had only a ligamentous connection to the braincase. However, previous suggestions that symmoriiforms were aphetohyoidean (with a complete hyoidean gill slit and “unmodified” hyoid arch) are not supported by morphological evidence.The systematic classification of symmoriiform sharks is in disarray. Symmoriiforms collectively are probably monophyletic, but within them only the family Falcatidae is characterized convincingly by synapomorphies. Remaining symmoriiforms have been traditionally classified as “stethacanthids” and “symmoriid

@article{doi1012060003009020073071tbipsa20co2,
    author = "Maisey, John G.",
    title = "THE BRAINCASE IN PALEOZOIC SYMMORIIFORM AND CLADOSELACHIAN SHARKS",
    year = "2007",
    journal = "Bulletin of the American Museum of Natural History",
    abstract = "The concepts of platytrabia/platybasia and tropibasia/tropitrabia in gnathostomes are reviewed. The terms platytrabia and tropitrabia refer to developmental states of the embryonic trabecular cartilages that can be determined only by ontogenetic studies. The terms platybasia and tropibasia originally had this meaning, but have subsequently taken on additional descriptive connotations involving morphological features in the prechordal part of the adult chondrocranium. However, platybasia and tropibasia are not synonymous with platytrabia and tropitrabia. In gnathostomes, platytrabia usually gives rise to a platybasic adult condition (but not invariably; e.g., Lepisosteus), and tropitrabia usually gives rise to the tropibasic condition (modern elasmobranchs may be an exception). Thus, ontogeny does not provide an absolute guide to the adult condition, nor does adult morphology provide an accurate means to assess the prior ontogenetic condition in gnathostomes. Platybasia and tropibasia are regarded here as useful morphological terms that can be applied to fossils or to extant forms for which ontogenetic data are not available (although it may still be possible to reach some ontogenetic conclusions, based on morphological observations).A well-preserved but disarticulated fossil symmoriiform shark braincase from the Pennsylvanian of Arkansas is described under the informal generic designation “Cobelodus”, using digital reconstructions made from a high-resolution computerized-tomography (CT) scan. The braincase is morphologically tropibasic and clearly represents a departure from the common platybasic pattern found in elasmobranchs (e.g., Tamiobatis, Cladodoides, Orthacanthus).The contribution made by the embryonic polar cartilage in “Cobelodus” was probably extensive (unlike in modern gnathostomes), as in the platybasic Paleozoic shark Cladodoides. Thus, tropibasia in “Cobelodus” seems to be superimposed on an already-specialized pattern of cranial morphology found in some early platybasic elasmobranchs. The basicranial arterial circuit in “Cobelodus” was highly modified, and its internal carotids could not have communicated with the cranial cavity via the bucco-hypophyseal chamber as in other elasmobranchs. Internal carotids either were absent or met the efferent pseudobranchials within the orbit before the combined vessel entered the cranial cavity via the orbital cartilage, but the arrangement was certainly not osteichthyan-like (where the combined internal carotid/efferent pseudobranchial arteries pass through the basisphenoid pillar).“Cobelodus” and many other Paleozoic sharks possessed a postorbital palatoquadrate articulation (possibly strengthened by ligaments above the articulation in “Cobelodus”), on cartilage presumably formed in the embryonic lateral commissure. This arrangement differs from that in amphistylic hexanchiform sharks, where the lateral commissure is absent and there is no postorbital arcade; the postorbital articulation is located instead on the primary postorbital process (an outgrowth of the supraorbital shelf). Hexanchiforms are the only extant elasmobranchs with a postorbital articulation, but do not occupy a basal position in modern morphological and molecular phylogenetic analyses. Amphistyly in hexanchiforms is therefore viewed as a derived state rather than a highly conserved feature.No hyomandibular facet has been identified in “Cobelodus”, suggesting that its epihyal had only a ligamentous connection to the braincase. However, previous suggestions that symmoriiforms were aphetohyoidean (with a complete hyoidean gill slit and “unmodified” hyoid arch) are not supported by morphological evidence.The systematic classification of symmoriiform sharks is in disarray. Symmoriiforms collectively are probably monophyletic, but within them only the family Falcatidae is characterized convincingly by synapomorphies. Remaining symmoriiforms have been traditionally classified as “stethacanthids” and “symmoriid",
    url = "https://doi.org/10.1206/0003-0090(2007)307[1:tbipsa]2.0.co;2",
    doi = "10.1206/0003-0090(2007)307[1:tbipsa]2.0.co;2",
    openalex = "W2128093094",
    references = "doi101002jmor10342"
}

ABSTRACT Cretalamna (=Cretolamna) appendiculata is an extinct lamniform shark primarily known by isolated teeth and traditionally classified into Cretoxyrhinidae. Here, a partial skeleton of C. appendiculata from the Upper Cretaceous Niobrara Chalk of Kansas is described. The reconstructed dentition partially corroborated with some articulated teeth on an upper jaw indicates that the shark had a lamnoid tooth pattern. Adjacent teeth apparently abutted each other without overlap and the dentition likely had a cutting function. The reconstruction presented here differs from previously published reconstructed dentitions of C. appendiculata based on isolated teeth or purely disarticulated tooth sets. The overall dental pattern of C. appendiculata is found to be more similar to the pattern of extant Lamna spp. than to that of a cretoxyrhinid, Cretoxyrhina mantelli, possibly indicating that Cretalamna appendiculata may not belong to Cretoxyrhinidae. The estimated jaw lengths indicate an upper jaw overbite, which concomitantly implies a subterminal mouth in the shark. The jaw morphology indicates the presence of large dorsal and ventral quadratomandibularis muscles. The vertebrae of C. appendiculata are confirmed to be of lamnoid type, reaffirming C. appendiculata to be a lamniform. Cretalamna appendiculata probably had a fusiform body with a caudal fin not as elongate as in modern alopiids. The C. appendiculata individual likely measured at least 2.3 m and possibly as large as 3 m in total length. The extant phylogenetic bracket approach indicates that C. appendiculata possessed a dental bulla in each jaw. Cretalamna appendiculata was probably an ecological generalist.

@article{doi10167102724634200727584sadaol20co2,
    author = "Shimada, Kenshu",
    title = "Skeletal and dental anatomy of lamniform shark, Cretalamna appendiculata, from Upper Cretaceous Niobrara Chalk of Kansas",
    year = "2007",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT Cretalamna (=Cretolamna) appendiculata is an extinct lamniform shark primarily known by isolated teeth and traditionally classified into Cretoxyrhinidae. Here, a partial skeleton of C. appendiculata from the Upper Cretaceous Niobrara Chalk of Kansas is described. The reconstructed dentition partially corroborated with some articulated teeth on an upper jaw indicates that the shark had a lamnoid tooth pattern. Adjacent teeth apparently abutted each other without overlap and the dentition likely had a cutting function. The reconstruction presented here differs from previously published reconstructed dentitions of C. appendiculata based on isolated teeth or purely disarticulated tooth sets. The overall dental pattern of C. appendiculata is found to be more similar to the pattern of extant Lamna spp. than to that of a cretoxyrhinid, Cretoxyrhina mantelli, possibly indicating that Cretalamna appendiculata may not belong to Cretoxyrhinidae. The estimated jaw lengths indicate an upper jaw overbite, which concomitantly implies a subterminal mouth in the shark. The jaw morphology indicates the presence of large dorsal and ventral quadratomandibularis muscles. The vertebrae of C. appendiculata are confirmed to be of lamnoid type, reaffirming C. appendiculata to be a lamniform. Cretalamna appendiculata probably had a fusiform body with a caudal fin not as elongate as in modern alopiids. The C. appendiculata individual likely measured at least 2.3 m and possibly as large as 3 m in total length. The extant phylogenetic bracket approach indicates that C. appendiculata possessed a dental bulla in each jaw. Cretalamna appendiculata was probably an ecological generalist.",
    url = "https://doi.org/10.1671/0272-4634(2007)27[584:sadaol]2.0.co;2",
    doi = "10.1671/0272-4634(2007)27[584:sadaol]2.0.co;2",
    openalex = "W2173992070",
    references = "doi101002jmor10342, doi101002jmor1073, doi101666002233602006801fmvftl20co2"
}

The concept of elasmobranch species using nursery areas was introduced in the early 1900s and has been an accepted aspect of shark biology and behavior for several decades. Despite several descriptions of how shark species use nursery areas and what types of regions nurseries may be found in, no explicit definition of what constitutes a shark nursery area has been presented. Here we evaluate the assumptions of the current shark nursery paradigm in light of available data. Based on examination of these assumptions and available methods of quantifying and accurately describing shark nursery areas, a new more quantitative definition of shark nursery areas is proposed. This definition requires 3 criteria to be met for an area to be identified as a nursery: (1) sharks are more commonly encountered in the area than other areas; (2) sharks have a tendency to remain or return for extended periods; and (3) the area or habitat is repeatedly used across years. These criteria make the definition of shark nursery areas more compatible with those for other aquatic species. The improved definition of this concept will provide more valuable information for fisheries managers and shark biologists.

@article{doi103354meps337287,
    author = "Heupel, Michelle R. and Carlson, JK and Simpfendorfer, Colin A.",
    title = "Shark nursery areas: concepts, definition, characterization and assumptions",
    year = "2007",
    journal = "Marine Ecology Progress Series",
    abstract = "The concept of elasmobranch species using nursery areas was introduced in the early 1900s and has been an accepted aspect of shark biology and behavior for several decades. Despite several descriptions of how shark species use nursery areas and what types of regions nurseries may be found in, no explicit definition of what constitutes a shark nursery area has been presented. Here we evaluate the assumptions of the current shark nursery paradigm in light of available data. Based on examination of these assumptions and available methods of quantifying and accurately describing shark nursery areas, a new more quantitative definition of shark nursery areas is proposed. This definition requires 3 criteria to be met for an area to be identified as a nursery: (1) sharks are more commonly encountered in the area than other areas; (2) sharks have a tendency to remain or return for extended periods; and (3) the area or habitat is repeatedly used across years. These criteria make the definition of shark nursery areas more compatible with those for other aquatic species. The improved definition of this concept will provide more valuable information for fisheries managers and shark biologists.",
    url = "https://doi.org/10.3354/meps337287",
    doi = "10.3354/meps337287",
    openalex = "W2081487017"
}

Ecotourism operations which provide food to large predators have the potential to negatively affect their target species, by conditioning them to associate humans with food, or by generally altering their behavioural patterns. This latter effect could have potentially detrimental consequences for the ecosystem inhabited by the predator, because any behavioural changes could affect the species with which they interact. We present the results of an experimental study conducted from June to October 2004, which examined the effects of provisioning ecotourism on the behaviour of white sharks around a seal colony on a small island in South Africa. Although ecotourism activity had an effect on the behaviour of some sharks, this was relatively minor, and the majority of sharks showed little interest in the food rewards on offer. It is unlikely that conditioning would occur from the amount of ecotourism activity tested, because even those sharks identified supplying most of the data presented here (which may be more strongly predisposed towards conditioning, as their persistence around the boat is what allowed them to be identified) showed a nearly ubiquitous trend of decreasing response with time. Furthermore, even the sharks frequently acquiring food rewards typically stopped responding after several interactions. Consequently, moderate levels of ecotourism probably have only a minor impact on the behaviour of white sharks, and are therefore unlikely to create behavioural effects at the ecosystem level.

@article{doi103354meps338199,
    author = "Laroche, RK and Kock, Alison and Dill, LM and Oosthuizen, W. H.",
    title = "Effects of provisioning ecotourism activity on the behaviour of white sharks Carcharodon carcharias",
    year = "2007",
    journal = "Marine Ecology Progress Series",
    abstract = "Ecotourism operations which provide food to large predators have the potential to negatively affect their target species, by conditioning them to associate humans with food, or by generally altering their behavioural patterns. This latter effect could have potentially detrimental consequences for the ecosystem inhabited by the predator, because any behavioural changes could affect the species with which they interact. We present the results of an experimental study conducted from June to October 2004, which examined the effects of provisioning ecotourism on the behaviour of white sharks around a seal colony on a small island in South Africa. Although ecotourism activity had an effect on the behaviour of some sharks, this was relatively minor, and the majority of sharks showed little interest in the food rewards on offer. It is unlikely that conditioning would occur from the amount of ecotourism activity tested, because even those sharks identified supplying most of the data presented here (which may be more strongly predisposed towards conditioning, as their persistence around the boat is what allowed them to be identified) showed a nearly ubiquitous trend of decreasing response with time. Furthermore, even the sharks frequently acquiring food rewards typically stopped responding after several interactions. Consequently, moderate levels of ecotourism probably have only a minor impact on the behaviour of white sharks, and are therefore unlikely to create behavioural effects at the ecosystem level.",
    url = "https://doi.org/10.3354/meps338199",
    doi = "10.3354/meps338199",
    openalex = "W1984632467",
    references = "doi101017s002531540501218x"
}

@article{doi101002aqc975,
    author = "Dulvy, Nicholas K. and Baum, Julia K. and Clarke, Shelley and Compagno, Leonard J. V. and Cortés, Enric and Domingo, Andrés and Fordham, Sonja V. and Fowler, Sarah and Francis, Malcolm P. and Gibson, Claudine and Martínez, Jimmy and Musick, John A. and Soldo, Alen and Stevens, John D. and Valenti, Sarah",
    title = "You can swim but you can't hide: the global status and conservation of oceanic pelagic sharks and rays",
    year = "2008",
    journal = "Aquatic Conservation Marine and Freshwater Ecosystems",
    url = "https://doi.org/10.1002/aqc.975",
    doi = "10.1002/aqc.975",
    openalex = "W2162461877",
    references = "openalexw570265017"
}

The nurse shark, Ginglymostoma cirratum, is an obligate suction feeder that preys on benthic invertebrates and fish. Its cranial morphology exhibits a suite of structural and functional modifications that facilitate this mode of prey capture. During suction-feeding, subambient pressure is generated by the ventral expansion of the hyoid apparatus and the floor of its buccopharyngeal cavity. As in suction-feeding bony fishes, the nurse shark exhibits expansive, compressive, and recovery kinematic phases that produce posterior-directed water flow through the buccopharyngeal cavity. However, there is generally neither a preparatory phase nor cranial elevation. Suction is generated by the rapid depression of the buccopharyngeal floor by the coracoarcualis, coracohyoideus, and coracobranchiales muscles. Because the hyoid arch of G. cirratum is loosely connected to the mandible, contraction of the rectus cervicis muscle group can greatly depress the floor of the buccopharyngeal cavity below the depressed mandible, resulting in large volumetric expansion. Suction pressures in the nurse shark vary greatly, but include the greatest subambient pressures reported for an aquatic-feeding vertebrate. Maximum suction pressure does not appear to be related to shark size, but is correlated with the rate of buccopharyngeal expansion. As in suction-feeding bony fishes, suction in the nurse shark is only effective within approximately 3 cm in front of the mouth. The foraging behavior of this shark is most likely constrained to ambushing or stalking due to the exponential decay of effective suction in front of the mouth. Prey capture may be facilitated by foraging within reef confines and close to the substrate, which can enhance the effective suction distance, or by foraging at night when it can more closely approach prey.

@article{doi101002jmor10626,
    author = "Motta, Philip and Hueter, Robert E. and Tricas, Timothy C. and Summers, Adam P. and Huber, Daniel R. and Lowry, Dayv and Mara, Kyle R. and Matott, Michael P. and Whitenack, Lisa B. and Wintzer, Alpa P.",
    title = "Functional morphology of the feeding apparatus, feeding constraints, and suction performance in the nurse shark Ginglymostoma cirratum",
    year = "2008",
    journal = "Journal of Morphology",
    abstract = "The nurse shark, Ginglymostoma cirratum, is an obligate suction feeder that preys on benthic invertebrates and fish. Its cranial morphology exhibits a suite of structural and functional modifications that facilitate this mode of prey capture. During suction-feeding, subambient pressure is generated by the ventral expansion of the hyoid apparatus and the floor of its buccopharyngeal cavity. As in suction-feeding bony fishes, the nurse shark exhibits expansive, compressive, and recovery kinematic phases that produce posterior-directed water flow through the buccopharyngeal cavity. However, there is generally neither a preparatory phase nor cranial elevation. Suction is generated by the rapid depression of the buccopharyngeal floor by the coracoarcualis, coracohyoideus, and coracobranchiales muscles. Because the hyoid arch of G. cirratum is loosely connected to the mandible, contraction of the rectus cervicis muscle group can greatly depress the floor of the buccopharyngeal cavity below the depressed mandible, resulting in large volumetric expansion. Suction pressures in the nurse shark vary greatly, but include the greatest subambient pressures reported for an aquatic-feeding vertebrate. Maximum suction pressure does not appear to be related to shark size, but is correlated with the rate of buccopharyngeal expansion. As in suction-feeding bony fishes, suction in the nurse shark is only effective within approximately 3 cm in front of the mouth. The foraging behavior of this shark is most likely constrained to ambushing or stalking due to the exponential decay of effective suction in front of the mouth. Prey capture may be facilitated by foraging within reef confines and close to the substrate, which can enhance the effective suction distance, or by foraging at night when it can more closely approach prey.",
    url = "https://doi.org/10.1002/jmor.10626",
    doi = "10.1002/jmor.10626",
    openalex = "W2100216999",
    references = "doi101093icbicm029"
}

Abstract Ontogenetic diet shifts are a widespread phenomenon among vertebrates, although their relationships with life history traits are poorly known. We analyzed the relative importance of body size, age and maturity stage as determinants of the diet of a marine top predator, the copper shark, Carcharhinus brachyurus, by examining stomach contents using a multiple‐hypothesis modeling approach. Copper sharks shifted their diet as size and age increased and as they became sexually mature, incorporated larger prey as they grew, and had a discrete shift in diet with body size, with only individuals larger than ≈200 cm total length able to prey on chondrichthyans. Body size was the most important trait explaining the consumption of chondrichthyans, while age determined the consumption of pelagic teleosts. Pelagic teleosts were consumed mostly by medium‐aged sharks, a result, probably, of a risk‐reducing feeding strategy at young ages coupled with either a senescence‐related decline in performance or a change in sensory capabilities as sharks age. Copper sharks of all sizes were able to cut prey in pieces, implying that gape limitation (i.e., the impossibility of eating prey larger than a predator's mouth) did not play a role in producing the diet shift. Our results suggest that, contrary to the current practice of setting minimum but not maximum size limits in catches, any plan to conserve or restore the ecological function of sharks, through their predatory control of large prey, should aim to maintain the largest individuals.

@article{doi101007s112840080487z,
    author = "Lucifora, Luis O. and García, Verónica B. and Menni, Roberto Carlos and Escalante, Alicia H. and Hozbor, Natalia M.",
    title = "Effects of body size, age and maturity stage on diet in a large shark: ecological and applied implications",
    year = "2008",
    journal = "Ecological Research",
    abstract = "Abstract Ontogenetic diet shifts are a widespread phenomenon among vertebrates, although their relationships with life history traits are poorly known. We analyzed the relative importance of body size, age and maturity stage as determinants of the diet of a marine top predator, the copper shark, Carcharhinus brachyurus, by examining stomach contents using a multiple‐hypothesis modeling approach. Copper sharks shifted their diet as size and age increased and as they became sexually mature, incorporated larger prey as they grew, and had a discrete shift in diet with body size, with only individuals larger than ≈200 cm total length able to prey on chondrichthyans. Body size was the most important trait explaining the consumption of chondrichthyans, while age determined the consumption of pelagic teleosts. Pelagic teleosts were consumed mostly by medium‐aged sharks, a result, probably, of a risk‐reducing feeding strategy at young ages coupled with either a senescence‐related decline in performance or a change in sensory capabilities as sharks age. Copper sharks of all sizes were able to cut prey in pieces, implying that gape limitation (i.e., the impossibility of eating prey larger than a predator's mouth) did not play a role in producing the diet shift. Our results suggest that, contrary to the current practice of setting minimum but not maximum size limits in catches, any plan to conserve or restore the ecological function of sharks, through their predatory control of large prey, should aim to maintain the largest individuals.",
    url = "https://doi.org/10.1007/s11284-008-0487-z",
    doi = "10.1007/s11284-008-0487-z",
    openalex = "W2030589701",
    references = "doi101007978940173245110, doi101023a1007649900712, doi101086498196, openalexw1511461941"
}

Abstract The notorious jaws of the white shark Carcharodon carcharias are widely feared, yet poorly understood. Neither its bite force, nor how such force might be delivered using relatively elastic cartilaginous jaws, have been quantified or described. We have digitally reconstructed the jaws of a white shark to estimate maximum bite force and examine relationships among their three‐dimensional geometry, material properties and function. We predict that bite force in large white sharks may exceed c. 1.8 tonnes, the highest known for any living species, and suggest that forces may have been an order of magnitude greater still in the gigantic fossil species Carcharodon megalodon. However, jaw adductor‐generated force in Carcharodon appears unremarkable when the predator's body mass is considered. Although the shark's cartilaginous jaws undergo considerably greater deformation than would jaws constructed of bone, effective bite force is not greatly diminished.

@article{doi101111j14697998200800494x,
    author = "Wroe, Stephen and Huber, Daniel R. and Lowry, Michael B. and McHenry, Colin R. and Moreno, Karen and Clausen, Philip and Ferrara, Toni L. and Cunningham, Eldon L. and Dean, Mason N. and Summers, Adam P.",
    title = "Three‐dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite?",
    year = "2008",
    journal = "Journal of Zoology",
    abstract = "Abstract The notorious jaws of the white shark Carcharodon carcharias are widely feared, yet poorly understood. Neither its bite force, nor how such force might be delivered using relatively elastic cartilaginous jaws, have been quantified or described. We have digitally reconstructed the jaws of a white shark to estimate maximum bite force and examine relationships among their three‐dimensional geometry, material properties and function. We predict that bite force in large white sharks may exceed c. 1.8 tonnes, the highest known for any living species, and suggest that forces may have been an order of magnitude greater still in the gigantic fossil species Carcharodon megalodon. However, jaw adductor‐generated force in Carcharodon appears unremarkable when the predator's body mass is considered. Although the shark's cartilaginous jaws undergo considerably greater deformation than would jaws constructed of bone, effective bite force is not greatly diminished.",
    url = "https://doi.org/10.1111/j.1469-7998.2008.00494.x",
    doi = "10.1111/j.1469-7998.2008.00494.x",
    openalex = "W2100271771",
    references = "diamond1986animal, doi101016135045339597314f, doi101017s002531540501218x, doi10103835059070, doi101038415035b, doi10108800319155411009, doi101098rspb20042986, doi1016710272463420050250478r20co2, doi10189000129658200788347bfaeat20co2, doi105281zenodo16136060, doi105281zenodo3739898, doi105860choice326223, openalexw596245786"
}

Abstract: Recent bulk sampling and study of museum collections has revealed a high diversity of hybodont sharks from the English Bathonian, with 15 species being recognised. In addition, study of dental and skeletal material from the English Callovian has allowed the diagnosis of a new genus and species, Planohybodus peterboroughensis gen. et sp. nov., allowing the Bathonian species Hybodus grossiconus Agassiz to be referred to Planohybodus. Two additional new genera, Secarodus and Frangerodus, are erected for the Bathonian taxa Hybodus polyprion Agassiz and Strophodus lingualis Woodward, respectively. Egertonodus duffini sp. nov. is described and the diagnosis of Egertonodus based on dental material is discussed. The previously unrecorded Hybodus sp., Parvodus sp., and Lonchidion sp. are recognised but left in open nomenclature. Asteracanthus medius (Owen) is recorded in the British Bathonian for the first time, and the status of Bathonian nominal species of Asteracanthus are assessed. Bathonian hybodonts showed great diversity in trophic ecology and many of the species are specific to particular palaeoenvironments.

@article{doi101111j14754983200700737x,
    author = "Rees, Jan and Underwood, Charlie J.",
    title = "HYBODONT SHARKS OF THE ENGLISH BATHONIAN AND CALLOVIAN (MIDDLE JURASSIC)",
    year = "2008",
    journal = "Palaeontology",
    abstract = "Abstract: Recent bulk sampling and study of museum collections has revealed a high diversity of hybodont sharks from the English Bathonian, with 15 species being recognised. In addition, study of dental and skeletal material from the English Callovian has allowed the diagnosis of a new genus and species, Planohybodus peterboroughensis gen. et sp. nov., allowing the Bathonian species Hybodus grossiconus Agassiz to be referred to Planohybodus. Two additional new genera, Secarodus and Frangerodus, are erected for the Bathonian taxa Hybodus polyprion Agassiz and Strophodus lingualis Woodward, respectively. Egertonodus duffini sp. nov. is described and the diagnosis of Egertonodus based on dental material is discussed. The previously unrecorded Hybodus sp., Parvodus sp., and Lonchidion sp. are recognised but left in open nomenclature. Asteracanthus medius (Owen) is recorded in the British Bathonian for the first time, and the status of Bathonian nominal species of Asteracanthus are assessed. Bathonian hybodonts showed great diversity in trophic ecology and many of the species are specific to particular palaeoenvironments.",
    url = "https://doi.org/10.1111/j.1475-4983.2007.00737.x",
    doi = "10.1111/j.1475-4983.2007.00737.x",
    openalex = "W1866753633",
    references = "doi105962bhltitle20094, doi105962p150189, openalexw595691412"
}

Evidence for severe declines in large predatory fishes is increasing around the world. Because of its long history of intense fishing, the Mediterranean Sea offers a unique perspective on fish population declines over historical timescales. We used a diverse set of records dating back to the early 19th and mid 20th century to reconstruct long-term population trends of large predatory sharks in the northwestern Mediterranean Sea. We compiled 9 time series of abundance indices from commercial and recreational fishery landings, scientific surveys, and sighting records. Generalized linear models were used to extract instantaneous rates of change from each data set, and a meta-analysis was conducted to compare population trends. Only 5 of the 20 species we considered had sufficient records for analysis. Hammerhead (Sphyrna spp.), blue (Prionace glauca), mackerel (Isurus oxyrinchus and Lamna nasus), and thresher sharks (Alopias vulpinus) declined between 96 and 99.99% relative to their former abundance. According to World Conservation Union (IUCN) criteria, these species would be considered critically endangered. So far, the lack of quantitative population assessments has impeded shark conservation in the Mediterranean Sea. Our study fills this critical information gap, suggesting that current levels of exploitation put large sharks at risk of extinction in the Mediterranean Sea. Possible ecosystem effects of these losses involve a disruption of top-down control and a release of midlevel consumers.

@article{doi101111j15231739200800938x,
    author = "Ferretti, Francesco and Myers, Ransom A. and Serena, Fabrizio and Lotze, Heike K.",
    title = "Loss of Large Predatory Sharks from the Mediterranean Sea",
    year = "2008",
    journal = "Conservation Biology",
    abstract = "Evidence for severe declines in large predatory fishes is increasing around the world. Because of its long history of intense fishing, the Mediterranean Sea offers a unique perspective on fish population declines over historical timescales. We used a diverse set of records dating back to the early 19th and mid 20th century to reconstruct long-term population trends of large predatory sharks in the northwestern Mediterranean Sea. We compiled 9 time series of abundance indices from commercial and recreational fishery landings, scientific surveys, and sighting records. Generalized linear models were used to extract instantaneous rates of change from each data set, and a meta-analysis was conducted to compare population trends. Only 5 of the 20 species we considered had sufficient records for analysis. Hammerhead (Sphyrna spp.), blue (Prionace glauca), mackerel (Isurus oxyrinchus and Lamna nasus), and thresher sharks (Alopias vulpinus) declined between 96 and 99.99\% relative to their former abundance. According to World Conservation Union (IUCN) criteria, these species would be considered critically endangered. So far, the lack of quantitative population assessments has impeded shark conservation in the Mediterranean Sea. Our study fills this critical information gap, suggesting that current levels of exploitation put large sharks at risk of extinction in the Mediterranean Sea. Possible ecosystem effects of these losses involve a disruption of top-down control and a release of midlevel consumers.",
    url = "https://doi.org/10.1111/j.1523-1739.2008.00938.x",
    doi = "10.1111/j.1523-1739.2008.00938.x",
    openalex = "W2139416678",
    references = "doi101006jmsc19990489"
}

SUMMARY As global fishing effort increasingly expands into deeper water, concerns exist over the ability of deep-sea fishes to sustain fisheries. There is however little quantitative evidence to support these concerns for the deep-sea cartilaginous fishes (Chondrichthyes: sharks, rays and chimaeras). This paper compiled available life history data for this group to analyse their ability to rebound from population declines relative to continental shelf and pelagic species. Deep-sea cartilaginous fishes have rates of population increase that are on average less than half those of shelf and pelagic species, and include the lowest levels observed to date. Population doubling times indicate that once a stock has been depleted, it will take decades, and potentially centuries, before it will recover. Furthermore, population recovery rates decrease with increasing depth, suggesting species that occur deepest are those most vulnerable to fishing. These results provide the first assessment of the productivity of deep-sea chondrichthyans, highlighting that precautionary management of developing deep-sea fisheries is essential if stocks and biodiversity are to be maintained.

@article{doi101017s0376892909990191,
    author = "Simpfendorfer, Colin A. and Kyne, Peter M.",
    title = "Limited potential to recover from overfishing raises concerns for deep-sea sharks, rays and chimaeras",
    year = "2009",
    journal = "Environmental Conservation",
    abstract = "SUMMARY As global fishing effort increasingly expands into deeper water, concerns exist over the ability of deep-sea fishes to sustain fisheries. There is however little quantitative evidence to support these concerns for the deep-sea cartilaginous fishes (Chondrichthyes: sharks, rays and chimaeras). This paper compiled available life history data for this group to analyse their ability to rebound from population declines relative to continental shelf and pelagic species. Deep-sea cartilaginous fishes have rates of population increase that are on average less than half those of shelf and pelagic species, and include the lowest levels observed to date. Population doubling times indicate that once a stock has been depleted, it will take decades, and potentially centuries, before it will recover. Furthermore, population recovery rates decrease with increasing depth, suggesting species that occur deepest are those most vulnerable to fishing. These results provide the first assessment of the productivity of deep-sea chondrichthyans, highlighting that precautionary management of developing deep-sea fisheries is essential if stocks and biodiversity are to be maintained.",
    url = "https://doi.org/10.1017/s0376892909990191",
    doi = "10.1017/s0376892909990191",
    openalex = "W2108351745",
    references = "doi101006jmsc20000722, doi101016s0169534702024928, doi101046j15231739200200416x, doi101071mf97135, doi101098rspb20071295, doi101111j14672979200600205x, doi101139f95233, doi1012019781003262190, doi1015771548844620000250006meadfs20co2, openalexw42114903"
}

Advances in electronic tagging and genetic research are making it possible to discern population structure for pelagic marine predators once thought to be panmictic. However, reconciling migration patterns and gene flow to define the resolution of discrete population management units remains a major challenge, and a vital conservation priority for threatened species such as oceanic sharks. Many such species have been flagged for international protection, yet effective population assessments and management actions are hindered by lack of knowledge about the geographical extent and size of distinct populations. Combining satellite tagging, passive acoustic monitoring and genetics, we reveal how eastern Pacific white sharks (Carcharodon carcharias) adhere to a highly predictable migratory cycle. Individuals persistently return to the same network of coastal hotspots following distant oceanic migrations and comprise a population genetically distinct from previously identified phylogenetic clades. We hypothesize that this strong homing behaviour has maintained the separation of a northeastern Pacific population following a historical introduction from Australia/New Zealand migrants during the Late Pleistocene. Concordance between contemporary movement and genetic divergence based on mitochondrial DNA demonstrates a demographically independent management unit not previously recognized. This population's fidelity to discrete and predictable locations offers clear population assessment, monitoring and management options.

@article{doi101098rspb20091155,
    author = "Jorgensen, Salvador J. and Reeb, Carol A. and Chapple, Taylor K. and Anderson, Scot D. and Perle, Christopher R. and Sommeran, Sean R. Van and Fritz-Cope, Callaghan and Brown, Adam and Klimley, A. Peter and Block, Barbara A.",
    title = "Philopatry and migration of Pacific white sharks",
    year = "2009",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "Advances in electronic tagging and genetic research are making it possible to discern population structure for pelagic marine predators once thought to be panmictic. However, reconciling migration patterns and gene flow to define the resolution of discrete population management units remains a major challenge, and a vital conservation priority for threatened species such as oceanic sharks. Many such species have been flagged for international protection, yet effective population assessments and management actions are hindered by lack of knowledge about the geographical extent and size of distinct populations. Combining satellite tagging, passive acoustic monitoring and genetics, we reveal how eastern Pacific white sharks (Carcharodon carcharias) adhere to a highly predictable migratory cycle. Individuals persistently return to the same network of coastal hotspots following distant oceanic migrations and comprise a population genetically distinct from previously identified phylogenetic clades. We hypothesize that this strong homing behaviour has maintained the separation of a northeastern Pacific population following a historical introduction from Australia/New Zealand migrants during the Late Pleistocene. Concordance between contemporary movement and genetic divergence based on mitochondrial DNA demonstrates a demographically independent management unit not previously recognized. This population's fidelity to discrete and predictable locations offers clear population assessment, monitoring and management options.",
    url = "https://doi.org/10.1098/rspb.2009.1155",
    doi = "10.1098/rspb.2009.1155",
    openalex = "W2156732093",
    references = "openalexw3190442888"
}

Klug, Stefanie, Kriwet, Jürgen, Böttcher, Ronald, Schweigert, Günter, Dietl, Gerd (2009): Skeletal anatomy of the extinct shark Paraorthacodus jurensis (Chondrichthyes; Palaeospinacidae), with comments on synechodontiform and palaeospinacid monophyly. Zoological Journal of the Linnean Society 157 (1): 107-134, DOI: 10.1111/j.1096-3642.2009.00534.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2009.00534.x

@article{doi101111j10963642200900534x,
    author = "Klug, Stefanie and Kriwet, Jürgen and Böttcher, Ronald and Schweigert, Günter and Dietl, Gerd",
    title = "Skeletal anatomy of the extinct shark Paraorthacodus jurensis (Chondrichthyes; Palaeospinacidae), with comments on synechodontiform and palaeospinacid monophyly",
    year = "2009",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "Klug, Stefanie, Kriwet, Jürgen, Böttcher, Ronald, Schweigert, Günter, Dietl, Gerd (2009): Skeletal anatomy of the extinct shark Paraorthacodus jurensis (Chondrichthyes; Palaeospinacidae), with comments on synechodontiform and palaeospinacid monophyly. Zoological Journal of the Linnean Society 157 (1): 107-134, DOI: 10.1111/j.1096-3642.2009.00534.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2009.00534.x",
    url = "https://doi.org/10.1111/j.1096-3642.2009.00534.x",
    doi = "10.1111/j.1096-3642.2009.00534.x",
    openalex = "W2016157686",
    references = "doi101002jmor1073, doi104072rbp2005205"
}

Abstract The role of learning in behaviour is well known for many animal taxa, including teleost fishes, insects, birds and mammals. However, its importance to sharks in everyday behavioural processes has rarely been considered. Almost 50 years ago the first learning experiments on sharks were conducted; our first section discusses these studies and places them in a framework of associative and non‐associative learning. These experiments showed that sharks were capable of different forms of learning, such as operant and classical conditioning and habituation. Sharks could learn associations as rapidly as other vertebrates and also remember training regimes for several months. However, much of this experimental evidence was based on small sample sizes and few shark orders, such as Carcharhiniformes and Orectobliformes, leaving large gaps in our knowledge of the general learning capabilities of other shark orders. We also examine recent research that has tested for, or inferred learning in behavioural processes. This section reveals that sharks, like teleost fishes use learning to improve prey search and capture to potentially navigate and orientate in their home range and recognize conspecifics, heterospecifics and mates. Learning is also discussed in relation to ecotourism and fisheries. Findings indicated that these activities may lead to conditioning of sharks and that considerable effort should go into investigating what impact this could have on the shark species involved. Finally, we discuss the importance of combining laboratory experiments with field studies, the use of new experimental techniques, the role of model species and research priorities for future work.

@article{doi101111j14672979200900339x,
    author = "Guttridge, Tristan L. and Myrberg, Arthur A. and Porcher, Ila France and Sims, David and Krause, Jens",
    title = "The role of learning in shark behaviour",
    year = "2009",
    journal = "Fish and Fisheries",
    abstract = "Abstract The role of learning in behaviour is well known for many animal taxa, including teleost fishes, insects, birds and mammals. However, its importance to sharks in everyday behavioural processes has rarely been considered. Almost 50 years ago the first learning experiments on sharks were conducted; our first section discusses these studies and places them in a framework of associative and non‐associative learning. These experiments showed that sharks were capable of different forms of learning, such as operant and classical conditioning and habituation. Sharks could learn associations as rapidly as other vertebrates and also remember training regimes for several months. However, much of this experimental evidence was based on small sample sizes and few shark orders, such as Carcharhiniformes and Orectobliformes, leaving large gaps in our knowledge of the general learning capabilities of other shark orders. We also examine recent research that has tested for, or inferred learning in behavioural processes. This section reveals that sharks, like teleost fishes use learning to improve prey search and capture to potentially navigate and orientate in their home range and recognize conspecifics, heterospecifics and mates. Learning is also discussed in relation to ecotourism and fisheries. Findings indicated that these activities may lead to conditioning of sharks and that considerable effort should go into investigating what impact this could have on the shark species involved. Finally, we discuss the importance of combining laboratory experiments with field studies, the use of new experimental techniques, the role of model species and research priorities for future work.",
    url = "https://doi.org/10.1111/j.1467-2979.2009.00339.x",
    doi = "10.1111/j.1467-2979.2009.00339.x",
    openalex = "W2037866588",
    references = "doi101093icbicm029, doi101159000100037, doi1023071442530"
}

Abstract This article summarizes catch data for sharks collected by fishery observers during two periods (1995–2000 and 2004–2006) in the Hawaii-based pelagic longline fishery, which targets swordfish Xiphias gladius in the shallow-set sector and bigeye tuna Thunnus obesus in the deep-set sector. The blue shark Prionace glauca was the predominant shark species caught throughout the study period (84.5% of all sharks). Five other species (bigeye thresher Alopias superciliosus, oceanic whitetip shark Carcharhinus longimanus, shortfin mako Isurus oxyrinchus, silky shark C. falciformis, and crocodile shark Pseudocarcharias kamoharai) were relatively common (1.0–4.1%). Two major developments affected shark catches in this fishery during the study period. The first was the prohibition in 2000 of shark finning under most circumstances. The second development was that management measures were taken in 2000 and 2001 to protect sea turtles (leatherback sea turtles Dermochelys coriacea and loggerhead sea turtles Caretta caretta) and these measures included a closure of the shallow-set (swordfish-targeting) sector for more than 3 years. The closure caused decreases in shark catches because the shallow-set sector was typically characterized by high catch rates. The shallow-set sector was reopened in 2004. Comparisons of nominal catch per unit effort (number of sharks/1,000 hooks) revealed significant differences in catch rates between the two fishery sectors and the two periods. Blue shark and shortfin mako catch rates were significantly greater in the shallow-set sector than in the deep-set sector of the fishery, whereas the opposite was true for the deeper-dwelling bigeye threshers and crocodile sharks. Catch rates for the blue shark, oceanic whitetip shark, bigeye thresher, and crocodile shark were significantly lower in 2004–2006 than in 1995–2000. For the blue shark in particular, the combination of reduced catch rates, the finning ban, and an apparent capacity to resist the stress of capture on longline gear resulted in low (4%–5.7%) minimum mortality estimates. Therefore, we conclude that the Hawaii-based pelagic longline fishery has made substantial progress in reducing shark mortality.

@article{doi101577c090031,
    author = "Walsh, William A. and Bigelow, Keith and Sender, Karen L.",
    title = "Decreases in Shark Catches and Mortality in the Hawaii-Based Longline Fishery as Documented by Fishery Observers",
    year = "2009",
    journal = "Marine and Coastal Fisheries",
    abstract = "Abstract This article summarizes catch data for sharks collected by fishery observers during two periods (1995–2000 and 2004–2006) in the Hawaii-based pelagic longline fishery, which targets swordfish Xiphias gladius in the shallow-set sector and bigeye tuna Thunnus obesus in the deep-set sector. The blue shark Prionace glauca was the predominant shark species caught throughout the study period (84.5\% of all sharks). Five other species (bigeye thresher Alopias superciliosus, oceanic whitetip shark Carcharhinus longimanus, shortfin mako Isurus oxyrinchus, silky shark C. falciformis, and crocodile shark Pseudocarcharias kamoharai) were relatively common (1.0–4.1\%). Two major developments affected shark catches in this fishery during the study period. The first was the prohibition in 2000 of shark finning under most circumstances. The second development was that management measures were taken in 2000 and 2001 to protect sea turtles (leatherback sea turtles Dermochelys coriacea and loggerhead sea turtles Caretta caretta) and these measures included a closure of the shallow-set (swordfish-targeting) sector for more than 3 years. The closure caused decreases in shark catches because the shallow-set sector was typically characterized by high catch rates. The shallow-set sector was reopened in 2004. Comparisons of nominal catch per unit effort (number of sharks/1,000 hooks) revealed significant differences in catch rates between the two fishery sectors and the two periods. Blue shark and shortfin mako catch rates were significantly greater in the shallow-set sector than in the deep-set sector of the fishery, whereas the opposite was true for the deeper-dwelling bigeye threshers and crocodile sharks. Catch rates for the blue shark, oceanic whitetip shark, bigeye thresher, and crocodile shark were significantly lower in 2004–2006 than in 1995–2000. For the blue shark in particular, the combination of reduced catch rates, the finning ban, and an apparent capacity to resist the stress of capture on longline gear resulted in low (4\%–5.7\%) minimum mortality estimates. Therefore, we conclude that the Hawaii-based pelagic longline fishery has made substantial progress in reducing shark mortality.",
    url = "https://doi.org/10.1577/c09-003.1",
    doi = "10.1577/c09-003.1",
    openalex = "W2150905376",
    references = "doi101201b118678"
}

ABSTRACT An exceptionally well-preserved white shark fossil (Carcharodon sp.) is described here from the early Pliocene (ca. 4 Ma) Pisco Formation of southwestern Peru. This specimen preserves 222 teeth and 45 vertebrae as well as fragmentary jaws. The teeth show characters of Carcharodon, including weak serrations and a symmetrical first anterior tooth that is the largest in the tooth row. This dentition also shows a character of Isurus with a distally inclined but mesially slanted intermediate tooth. Although the Pisco specimen demonstrates characters of both Isurus, also known form the Pisco Formation, and modern Carcharodon carcharias, it is assigned to the genus Carcharodon and referred to herein as Carcharodon sp. While Carcharodon sp. From the Pisco Formation shows numerous diagnostic characteristics shared with C. carcharias, it differs from the extant species in having a distal inclination of the intermediate tooth. The precaudal vertebral centra of the Pisco Carcharodon preserve distinctive dark and light incremental bands that, based on calibration with oxygen isotopes, indicate annular growth couplets. The fossil shark was at least 20 (±1) years old at the time of its death. Based on measurements of teeth and vertebral centra, this specimen is estimated to have had a minimum total body length of 4.80-5.07 m, similar to estimates for modern older individuals of C. carcharias. Relative to the extant Carcharodon carcharias, the Pisco Carcharodon sp. grew at a slower rate. The fossil record of lamnoid sharks preserved in the Pisco Formation demonstrates that the modern white shark is more closely related to Isurus (I. hastalis) than it is to the species Carcharodon megalodon, and the latter is therefore best allocated to the genus Carcharocles.

@article{doi1016710390290113,
    author = "Ehret, Dana J. and Hubbell, Gordon and MacFadden, Bruce J.",
    title = "Exceptional preservation of the white shark Carcharodon (Lamniformes, Lamnidae) from the early Pliocene of Peru",
    year = "2009",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT An exceptionally well-preserved white shark fossil (Carcharodon sp.) is described here from the early Pliocene (ca. 4 Ma) Pisco Formation of southwestern Peru. This specimen preserves 222 teeth and 45 vertebrae as well as fragmentary jaws. The teeth show characters of Carcharodon, including weak serrations and a symmetrical first anterior tooth that is the largest in the tooth row. This dentition also shows a character of Isurus with a distally inclined but mesially slanted intermediate tooth. Although the Pisco specimen demonstrates characters of both Isurus, also known form the Pisco Formation, and modern Carcharodon carcharias, it is assigned to the genus Carcharodon and referred to herein as Carcharodon sp. While Carcharodon sp. From the Pisco Formation shows numerous diagnostic characteristics shared with C. carcharias, it differs from the extant species in having a distal inclination of the intermediate tooth. The precaudal vertebral centra of the Pisco Carcharodon preserve distinctive dark and light incremental bands that, based on calibration with oxygen isotopes, indicate annular growth couplets. The fossil shark was at least 20 (±1) years old at the time of its death. Based on measurements of teeth and vertebral centra, this specimen is estimated to have had a minimum total body length of 4.80-5.07 m, similar to estimates for modern older individuals of C. carcharias. Relative to the extant Carcharodon carcharias, the Pisco Carcharodon sp. grew at a slower rate. The fossil record of lamnoid sharks preserved in the Pisco Formation demonstrates that the modern white shark is more closely related to Isurus (I. hastalis) than it is to the species Carcharodon megalodon, and the latter is therefore best allocated to the genus Carcharocles.",
    url = "https://doi.org/10.1671/039.029.0113",
    doi = "10.1671/039.029.0113",
    openalex = "W2029639849",
    references = "doi101002jmor1073"
}

The majority of studies on the evolution and function of feeding in sharks have focused primarily on the movement of cranial components and muscle function, with little integration of tooth properties or function. As teeth are subjected to sometimes extreme loads during feeding, they undergo stress, strain, and potential failure. As attributes related to structural strength such as material properties and overall shape may be subjected to natural selection, both prey processing ability and structural parameters must be considered to understand the evolution of shark teeth. In this study, finite element analysis was used to visualize stress distributions of fossil and extant shark teeth during puncture, unidirectional draw (cutting), and holding. Under the loading and boundary conditions here, which are consistent with bite forces of large sharks, shark teeth are structurally strong. Teeth loaded in puncture have localized stress concentrations at the cusp apex that diminish rapidly away from the apex. When loaded in draw and holding, the majority of the teeth show stress concentrations consistent with well designed cantilever beams. Notches result in stress concentration during draw and may serve as a weak point; however they are functionally important for cutting prey during lateral head shaking behavior. As shark teeth are replaced regularly, it is proposed that the frequency of tooth replacement in sharks is driven by tooth wear, not tooth failure. As the tooth tip and cutting edges are worn, the surface areas of these features increase, decreasing the amount of stress produced by the tooth. While this wear will not affect the general structural strength of the tooth, tooth replacement may also serve to keep ahead of damage caused by fatigue that may lead to eventual tooth failure.

@article{doi101002jmor10903,
    author = "Whitenack, Lisa B. and Simkins, Daniel C. and Motta, Philip",
    title = "Biology meets engineering: The structural mechanics of fossil and extant shark teeth",
    year = "2010",
    journal = "Journal of Morphology",
    abstract = "The majority of studies on the evolution and function of feeding in sharks have focused primarily on the movement of cranial components and muscle function, with little integration of tooth properties or function. As teeth are subjected to sometimes extreme loads during feeding, they undergo stress, strain, and potential failure. As attributes related to structural strength such as material properties and overall shape may be subjected to natural selection, both prey processing ability and structural parameters must be considered to understand the evolution of shark teeth. In this study, finite element analysis was used to visualize stress distributions of fossil and extant shark teeth during puncture, unidirectional draw (cutting), and holding. Under the loading and boundary conditions here, which are consistent with bite forces of large sharks, shark teeth are structurally strong. Teeth loaded in puncture have localized stress concentrations at the cusp apex that diminish rapidly away from the apex. When loaded in draw and holding, the majority of the teeth show stress concentrations consistent with well designed cantilever beams. Notches result in stress concentration during draw and may serve as a weak point; however they are functionally important for cutting prey during lateral head shaking behavior. As shark teeth are replaced regularly, it is proposed that the frequency of tooth replacement in sharks is driven by tooth wear, not tooth failure. As the tooth tip and cutting edges are worn, the surface areas of these features increase, decreasing the amount of stress produced by the tooth. While this wear will not affect the general structural strength of the tooth, tooth replacement may also serve to keep ahead of damage caused by fatigue that may lead to eventual tooth failure.",
    url = "https://doi.org/10.1002/jmor.10903",
    doi = "10.1002/jmor.10903",
    openalex = "W2062847800",
    references = "doi1023071445562"
}

@article{doi101007s002270101463z,
    author = "Flewelling, Leanne J. and Adams, Douglas H. and Naar, Jérôme and Atwood, Karen and Granholm, April A. and O’Dea, Sheila N. and Landsberg, Jan H.",
    title = "Brevetoxins in sharks and rays (Chondrichthyes, Elasmobranchii) from Florida coastal waters",
    year = "2010",
    journal = "Marine Biology",
    url = "https://doi.org/10.1007/s00227-010-1463-z",
    doi = "10.1007/s00227-010-1463-z",
    openalex = "W2008865007",
    references = "doi101006jmsc19990489, doi1010160025326x74900113, doi101016jhal200811010, doi101016s0305049197002721, doi101038nature435755a, doi101038s41467021267984, doi101071mf03023, doi10108020026491051695, doi1012019780203165577, doi104319lo1997425part21039"
}

@article{doi101016jympev201011018,
    author = "Vélez‐Zuazo, Ximena and Agnarsson, Ingi",
    title = "Shark tales: A molecular species-level phylogeny of sharks (Selachimorpha, Chondrichthyes)",
    year = "2010",
    journal = "Molecular Phylogenetics and Evolution",
    url = "https://doi.org/10.1016/j.ympev.2010.11.018",
    doi = "10.1016/j.ympev.2010.11.018",
    openalex = "W2018060126",
    references = "crossref1997interrelationships, openalexw3211386673"
}

Several patterns of brain allometry previously observed in mammals have been found to hold for sharks and related taxa (chondrichthyans) as well. In each clade, the relative size of brain parts, with the notable exception of the olfactory bulbs, is highly predictable from the total brain size. Compared with total brain mass, each part scales with a characteristic slope, which is highest for the telencephalon and cerebellum. In addition, cerebellar foliation reflects both absolute and relative cerebellar size, in a manner analogous to mammalian cortical gyrification. This conserved pattern of brain scaling suggests that the fundamental brain plan that evolved in early vertebrates permits appropriate scaling in response to a range of factors, including phylogeny and ecology, where neural mass may be added and subtracted without compromising basic function.

@article{doi101073pnas1002195107,
    author = "Yopak, Kara E. and Lisney, Thomas J. and Darlington, Richard B. and Collin, Shaun P. and Montgomery, John C. and Finlay, Barbara L.",
    title = "A conserved pattern of brain scaling from sharks to primates",
    year = "2010",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Several patterns of brain allometry previously observed in mammals have been found to hold for sharks and related taxa (chondrichthyans) as well. In each clade, the relative size of brain parts, with the notable exception of the olfactory bulbs, is highly predictable from the total brain size. Compared with total brain mass, each part scales with a characteristic slope, which is highest for the telencephalon and cerebellum. In addition, cerebellar foliation reflects both absolute and relative cerebellar size, in a manner analogous to mammalian cortical gyrification. This conserved pattern of brain scaling suggests that the fundamental brain plan that evolved in early vertebrates permits appropriate scaling in response to a range of factors, including phylogeny and ecology, where neural mass may be added and subtracted without compromising basic function.",
    url = "https://doi.org/10.1073/pnas.1002195107",
    doi = "10.1073/pnas.1002195107",
    openalex = "W2110680265",
    references = "doi101016b9780126709506500035, doi10103835016580, doi101038385313a0, doi101086284325, doi101086303327, doi101109jra19861087032, doi101126science1061967, doi101126science7777856, doi101159000100037, doi101159000155963, doi1023072407154, doi1023072412482"
}

With our increasing ability for generating whole-genome sequences, comparative analysis of whole genomes has become a powerful tool for understanding the structure, function, and evolutionary history of human and other vertebrate genomes. By virtue of their position basal to bony vertebrates, cartilaginous fishes (class Chondrichthyes) are a valuable outgroup in comparative studies of vertebrates. Recently, a holocephalan cartilaginous fish, the elephant shark, Callorhinchus milii (Subclass Holocephali: Order Chimaeriformes), has been proposed as a model genome, and low-coverage sequence of its genome has been generated. Despite such an increasing interest, the evolutionary history of the modern holocephalans-a previously successful and diverse group but represented by only 39 extant species-and their relationship with elasmobranchs and other jawed vertebrates has been poorly documented largely owing to a lack of well-preserved fossil materials after the end-Permian about 250 Ma. In this study, we assembled the whole mitogenome sequences for eight representatives from all the three families of the modern holocephalans and investigated their phylogenetic relationships and evolutionary history. Unambiguously aligned sequences from these holocephalans together with 17 other vertebrates (9,409 nt positions excluding entire third codon positions) were subjected to partitioned maximum likelihood analysis. The resulting tree strongly supported a single origin of the modern holocephalans and their sister-group relationship with elasmobranchs. The mitogenomic tree recovered the most basal callorhinchids within the chimaeriforms, which is sister to a clade comprising the remaining two families (rhinochimaerids and chimaerids). The timetree derived from a relaxed molecular clock Bayesian method suggests that the holocephalans originated in the Silurian about 420 Ma, having survived from the end-Permian (250 Ma) mass extinction and undergoing familial diversifications during the late Jurassic to early Cretaceous (170-120 Ma). This postulated evolutionary scenario agrees well with that based on the paleontological observations.

@article{doi101093molbevmsq147,
    author = "Inoue, Jun and Miya, Masaki and Lam, Kong‐Peng and Tay, Boon‐Hui and Danks, Janine A. and Bell, Justin D. and Walker, Terry I and Venkatesh, Byrappa",
    title = "Evolutionary Origin and Phylogeny of the Modern Holocephalans (Chondrichthyes: Chimaeriformes): A Mitogenomic Perspective",
    year = "2010",
    journal = "Molecular Biology and Evolution",
    abstract = "With our increasing ability for generating whole-genome sequences, comparative analysis of whole genomes has become a powerful tool for understanding the structure, function, and evolutionary history of human and other vertebrate genomes. By virtue of their position basal to bony vertebrates, cartilaginous fishes (class Chondrichthyes) are a valuable outgroup in comparative studies of vertebrates. Recently, a holocephalan cartilaginous fish, the elephant shark, Callorhinchus milii (Subclass Holocephali: Order Chimaeriformes), has been proposed as a model genome, and low-coverage sequence of its genome has been generated. Despite such an increasing interest, the evolutionary history of the modern holocephalans-a previously successful and diverse group but represented by only 39 extant species-and their relationship with elasmobranchs and other jawed vertebrates has been poorly documented largely owing to a lack of well-preserved fossil materials after the end-Permian about 250 Ma. In this study, we assembled the whole mitogenome sequences for eight representatives from all the three families of the modern holocephalans and investigated their phylogenetic relationships and evolutionary history. Unambiguously aligned sequences from these holocephalans together with 17 other vertebrates (9,409 nt positions excluding entire third codon positions) were subjected to partitioned maximum likelihood analysis. The resulting tree strongly supported a single origin of the modern holocephalans and their sister-group relationship with elasmobranchs. The mitogenomic tree recovered the most basal callorhinchids within the chimaeriforms, which is sister to a clade comprising the remaining two families (rhinochimaerids and chimaerids). The timetree derived from a relaxed molecular clock Bayesian method suggests that the holocephalans originated in the Silurian about 420 Ma, having survived from the end-Permian (250 Ma) mass extinction and undergoing familial diversifications during the late Jurassic to early Cretaceous (170-120 Ma). This postulated evolutionary scenario agrees well with that based on the paleontological observations.",
    url = "https://doi.org/10.1093/molbev/msq147",
    doi = "10.1093/molbev/msq147",
    openalex = "W1992975997",
    references = "doi101007bf00160154, doi101007bf01731581, doi10108010635150290069913, doi101093bioinformatics149817, doi101093bioinformatics17121246, doi101093bioinformaticsbtl446, doi101093bioscience1610752a, doi101093molbevmsm088, doi101093nargki198, doi101093oxfordjournalsmolbeva025811, doi101098rstb20051716, doi101201b118678, doi101643004585112002002053220co2"
}

Whereas many land predators disappeared before their ecological roles were studied, the decline of marine apex predators is still unfolding. Large sharks in particular have experienced rapid declines over the last decades. In this study, we review the documented changes in exploited elasmobranch communities in coastal, demersal, and pelagic habitats, and synthesize the effects of sharks on their prey and wider communities. We show that the high natural diversity and abundance of sharks is vulnerable to even light fishing pressure. The decline of large predatory sharks reduces natural mortality in a range of prey, contributing to changes in abundance, distribution, and behaviour of small elasmobranchs, marine mammals, and sea turtles that have few other predators. Through direct predation and behavioural modifications, top-down effects of sharks have led to cascading changes in some coastal ecosystems. In demersal and pelagic communities, there is increasing evidence of mesopredator release, but cascading effects are more hypothetical. Here, fishing pressure on mesopredators may mask or even reverse some ecosystem effects. In conclusion, large sharks can exert strong top-down forces with the potential to shape marine communities over large spatial and temporal scales. Yet more empirical evidence is needed to test the generality of these effects throughout the ocean.

@article{doi101111j14610248201001489x,
    author = "Ferretti, Francesco and Worm, Boris and Britten, Gregory L. and Heithaus, Michael R. and Lotze, Heike K.",
    title = "Patterns and ecosystem consequences of shark declines in the ocean",
    year = "2010",
    journal = "Ecology Letters",
    abstract = "Whereas many land predators disappeared before their ecological roles were studied, the decline of marine apex predators is still unfolding. Large sharks in particular have experienced rapid declines over the last decades. In this study, we review the documented changes in exploited elasmobranch communities in coastal, demersal, and pelagic habitats, and synthesize the effects of sharks on their prey and wider communities. We show that the high natural diversity and abundance of sharks is vulnerable to even light fishing pressure. The decline of large predatory sharks reduces natural mortality in a range of prey, contributing to changes in abundance, distribution, and behaviour of small elasmobranchs, marine mammals, and sea turtles that have few other predators. Through direct predation and behavioural modifications, top-down effects of sharks have led to cascading changes in some coastal ecosystems. In demersal and pelagic communities, there is increasing evidence of mesopredator release, but cascading effects are more hypothetical. Here, fishing pressure on mesopredators may mask or even reverse some ecosystem effects. In conclusion, large sharks can exert strong top-down forces with the potential to shape marine communities over large spatial and temporal scales. Yet more empirical evidence is needed to test the generality of these effects throughout the ocean.",
    url = "https://doi.org/10.1111/j.1461-0248.2010.01489.x",
    doi = "10.1111/j.1461-0248.2010.01489.x",
    openalex = "W2168963665",
    references = "doi101093icbicm029, doi101201b118678"
}

Global declines of shark populations are of concern because of their largely assumed role as moderators of ecosystem function. Without long-term data on movement patterns for many species, it is impossible to infer relative extinction risk, which varies as a function of range, dispersal and habitat specificity and use. The past 50 yr of research on coastal sharks has revealed common movement patterns among species. In the horizontal plane, measured home range size generally increases with body size. We demonstrate meta-analytically the effects of increasing body size and monitoring time on home range size. Changes in the extent of horizontal movement might arise from ontogeny, predator avoidance or environmental tolerances. In the vertical plane, movement patterns include oscillatory vertical displacement, surface swimming, diel vertical migration and swimming at depth. These vertical movements are often attributed to foraging or navigation, but have been quantified less than horizontal patterns. Habitat specificity is often correlated with environmental conditions such as depth, salinity, substratum, and in some cases, prey availability. Site fidelity is common in species that use nursery areas. However, fidelity to mating, pupping, feeding and natal sites has only been observed in a few species. To date, few studies have examined habitat partitioning, although some general patterns have emerged: habitats appear to be subdivided by benthos type, prey availability and depth. The conservation of coastal sharks can be facilitated in some cases by the use of marine protected areas, especially for coastal resident species using specific nursery, reproduction or feeding areas. Partial protected-area closures might be effective during aggregation or migration periods to protect older size classes, but these must be applied with other management strategies such as reduced fishing and size or bag limits to protect individuals throughout different life history phases. More long-term research on habitat use, migration patterns and habitat partitioning is essential for developing successful management initiatives for coastal shark populations.

@article{doi103354meps08581,
    author = "Speed, Conrad W. and Field, IC and Meekan, Mark G. and Bradshaw, CJA",
    title = "Complexities of coastal shark movements and their implications for management",
    year = "2010",
    journal = "Marine Ecology Progress Series",
    abstract = "Global declines of shark populations are of concern because of their largely assumed role as moderators of ecosystem function. Without long-term data on movement patterns for many species, it is impossible to infer relative extinction risk, which varies as a function of range, dispersal and habitat specificity and use. The past 50 yr of research on coastal sharks has revealed common movement patterns among species. In the horizontal plane, measured home range size generally increases with body size. We demonstrate meta-analytically the effects of increasing body size and monitoring time on home range size. Changes in the extent of horizontal movement might arise from ontogeny, predator avoidance or environmental tolerances. In the vertical plane, movement patterns include oscillatory vertical displacement, surface swimming, diel vertical migration and swimming at depth. These vertical movements are often attributed to foraging or navigation, but have been quantified less than horizontal patterns. Habitat specificity is often correlated with environmental conditions such as depth, salinity, substratum, and in some cases, prey availability. Site fidelity is common in species that use nursery areas. However, fidelity to mating, pupping, feeding and natal sites has only been observed in a few species. To date, few studies have examined habitat partitioning, although some general patterns have emerged: habitats appear to be subdivided by benthos type, prey availability and depth. The conservation of coastal sharks can be facilitated in some cases by the use of marine protected areas, especially for coastal resident species using specific nursery, reproduction or feeding areas. Partial protected-area closures might be effective during aggregation or migration periods to protect older size classes, but these must be applied with other management strategies such as reduced fishing and size or bag limits to protect individuals throughout different life history phases. More long-term research on habitat use, migration patterns and habitat partitioning is essential for developing successful management initiatives for coastal shark populations.",
    url = "https://doi.org/10.3354/meps08581",
    doi = "10.3354/meps08581",
    openalex = "W1999647795",
    references = "doi101006jmsc19990489, doi101006jmsc20000724, doi101007s0022700107117, doi101016jtree200801003, doi101016jtree200803011, doi101016s0169534799017231, doi101023a1007656126281, doi101023a1014200301213, doi101038nature01610, doi101038nature06518, doi101086282264, doi101086498196, doi101111j13652656200801512x, doi101126science1059199, doi101126science1138657, doi1023073802723, doi103354meps338211"
}

@article{doi101007s1053101101897,
    author = "Lucifora, Luis O. and García, Verónica B. and Menni, Roberto Carlos and Worm, Boris",
    title = "Spatial patterns in the diversity of sharks, rays, and chimaeras (Chondrichthyes) in the Southwest Atlantic",
    year = "2011",
    journal = "Biodiversity and Conservation",
    url = "https://doi.org/10.1007/s10531-011-0189-7",
    doi = "10.1007/s10531-011-0189-7",
    openalex = "W2029876830",
    references = "doi1010079780387217062, doi101016jtree200310013, doi101073pnas0803833105, doi10108000401706199710485142, doi101093biomet371217, doi101126science27753341956, doi101126science2795352860, doi1012019781420010404, doi1023073803199, openalexw2346841190"
}

@article{doi101016jympev201112012,
    author = "Aschliman, Neil C. and Nishida, Mutsumi and Miya, Masaki and Inoue, Jun and Rosana, Kerri M. and Naylor, Gavin J. P.",
    title = "Body plan convergence in the evolution of skates and rays (Chondrichthyes: Batoidea)",
    year = "2011",
    journal = "Molecular Phylogenetics and Evolution",
    url = "https://doi.org/10.1016/j.ympev.2011.12.012",
    doi = "10.1016/j.ympev.2011.12.012",
    openalex = "W1966910664",
    references = "crossref1997interrelationships, doi101093molbevmsq147, doi101111j109636421996tb02189x, doi101242jeb2042379, doi1023071447424, openalexw3211386673"
}

Growing concern for the world’s shark and ray populations is driving the need for greater research to inform conservation management. A change in public perception, from one that we need to protect humans from sharks to one where we must protect sharks from humans, has added to calls for better management. The present paper examines the growing need for research for conservation management of sharks and rays by synthesising information presented in this Special Issue from the 2010 Sharks International Conference and by identifying future research needs, including topics such as taxonomy, life history, population status, spatial ecology, environmental effects, ecosystem role and human impacts. However, this biological and ecological research agenda will not be sufficient to fully secure conservation management. There is also a need for research to inform social and economic sustainability. Effective conservation management will be achieved by setting clear priorities for research with the aid of stakeholders, implementing well designed research projects, building the capacity for research, and clearly communicating the results to stakeholders. If this can be achieved, it will assure a future for this iconic group, the ecosystems in which they occur and the human communities that rely on them.

@article{doi101071mf11086,
    author = "Simpfendorfer, Colin A. and Heupel, Michelle R. and White, William T. and Dulvy, Nicholas K.",
    title = "The importance of research and public opinion to conservation management of sharks and rays: a synthesis",
    year = "2011",
    journal = "Marine and Freshwater Research",
    abstract = "Growing concern for the world’s shark and ray populations is driving the need for greater research to inform conservation management. A change in public perception, from one that we need to protect humans from sharks to one where we must protect sharks from humans, has added to calls for better management. The present paper examines the growing need for research for conservation management of sharks and rays by synthesising information presented in this Special Issue from the 2010 Sharks International Conference and by identifying future research needs, including topics such as taxonomy, life history, population status, spatial ecology, environmental effects, ecosystem role and human impacts. However, this biological and ecological research agenda will not be sufficient to fully secure conservation management. There is also a need for research to inform social and economic sustainability. Effective conservation management will be achieved by setting clear priorities for research with the aid of stakeholders, implementing well designed research projects, building the capacity for research, and clearly communicating the results to stakeholders. If this can be achieved, it will assure a future for this iconic group, the ecosystems in which they occur and the human communities that rely on them.",
    url = "https://doi.org/10.1071/mf11086",
    doi = "10.1071/mf11086",
    openalex = "W2136069762",
    references = "doi101017s0376892909990191, doi101111j13652486200902128x"
}

Abstract Many coastal shark species use shallow estuarine regions as nursery habitat, but there are considerable gaps in our understanding of the seasonal distribution and habitat use patterns of sharks within these systems. We compiled all available sampling data from the Indian River Lagoon (IRL) along Florida's central Atlantic coast to examine the distribution of bull sharks Carcharhinus leucas. The data synthesized in this study spanned the 30‐year period 1975–2005 and included information on the seasonal distribution, size structure, and habitat associations of 449 bull sharks. For comparison, data from an additional 106 bull sharks captured in shelf waters adjacent to the IRL were also examined. The IRL is dominated by young‐of‐the‐year (age‐0) and juvenile bull sharks, which were most abundant during spring, summer, and autumn. Shark captures were most often associated with shallow freshwater creeks, power plant outfalls, ocean inlets, and seagrass habitats with temperatures greater than 20°C, salinities of 10–30‰, and dissolved oxygen concentrations between 4 and 7 mg/L. Juvenile bull sharks were found in waters with higher mean salinities than were age‐0 sharks. Although the IRL is one of the most important bull shark nursery areas on the U.S. Atlantic coast, catch‐per‐unit‐effort data indicate that bull shark abundance decreases with increasing latitude within and north of the IRL, suggesting that the IRL is the northern limit of functional nursery habitat for this species in the northwest Atlantic Ocean.

@article{doi101080000284872011618352,
    author = "Curtis, Tobey H. and Adams, Douglas H. and Burgess, George H.",
    title = "Seasonal Distribution and Habitat Associations of Bull Sharks in the Indian River Lagoon, Florida: A 30‐Year Synthesis",
    year = "2011",
    journal = "Transactions of the American Fisheries Society",
    abstract = "Abstract Many coastal shark species use shallow estuarine regions as nursery habitat, but there are considerable gaps in our understanding of the seasonal distribution and habitat use patterns of sharks within these systems. We compiled all available sampling data from the Indian River Lagoon (IRL) along Florida's central Atlantic coast to examine the distribution of bull sharks Carcharhinus leucas. The data synthesized in this study spanned the 30‐year period 1975–2005 and included information on the seasonal distribution, size structure, and habitat associations of 449 bull sharks. For comparison, data from an additional 106 bull sharks captured in shelf waters adjacent to the IRL were also examined. The IRL is dominated by young‐of‐the‐year (age‐0) and juvenile bull sharks, which were most abundant during spring, summer, and autumn. Shark captures were most often associated with shallow freshwater creeks, power plant outfalls, ocean inlets, and seagrass habitats with temperatures greater than 20°C, salinities of 10–30‰, and dissolved oxygen concentrations between 4 and 7 mg/L. Juvenile bull sharks were found in waters with higher mean salinities than were age‐0 sharks. Although the IRL is one of the most important bull shark nursery areas on the U.S. Atlantic coast, catch‐per‐unit‐effort data indicate that bull shark abundance decreases with increasing latitude within and north of the IRL, suggesting that the IRL is the northern limit of functional nursery habitat for this species in the northwest Atlantic Ocean.",
    url = "https://doi.org/10.1080/00028487.2011.618352",
    doi = "10.1080/00028487.2011.618352",
    openalex = "W2157691243",
    references = "doi10100797894017345094, doi101007bf00842902, doi101007s002270101463z, doi101016jchemosphere200710002, doi101021es051551y, doi101071mf01132, doi1016410006356820010510633ticamo20co2, doi103354meps337287, doi105962bhltitle3596, openalexw3008158973, openalexw570265017"
}

Ecotourism represents a highly popularised activity which has exhibited global growth in recent years. In the present paper, we examine the distribution, frequency, and economic value of shark-based ecotourism operations worldwide. A total of 376 shark ecotour operations across 83 locations and 8 geographic regions were identified. Here we describe the global and regional scope of the industry; determine the species utilised in shark ecotourism activities; and examine the recreational usage values of sharks. Further, we conducted a case study of a shark tourism operation based in South Africa by analysing 12 years of demographical and economical data, revealing increasing trends in the total number of customers served and cost per trip over the sampling period. We also compare consumptive and non-consumptive values of shark resources and discuss the potential research and conservation implications of the industry to sharks worldwide.

@article{doi101080136835002011585227,
    author = "Gallagher, Austin J. and Hammerschlag, Neil",
    title = "Global shark currency: the distribution, frequency, and economic value of shark ecotourism",
    year = "2011",
    journal = "Current Issues in Tourism",
    abstract = "Ecotourism represents a highly popularised activity which has exhibited global growth in recent years. In the present paper, we examine the distribution, frequency, and economic value of shark-based ecotourism operations worldwide. A total of 376 shark ecotour operations across 83 locations and 8 geographic regions were identified. Here we describe the global and regional scope of the industry; determine the species utilised in shark ecotourism activities; and examine the recreational usage values of sharks. Further, we conducted a case study of a shark tourism operation based in South Africa by analysing 12 years of demographical and economical data, revealing increasing trends in the total number of customers served and cost per trip over the sampling period. We also compare consumptive and non-consumptive values of shark resources and discuss the potential research and conservation implications of the industry to sharks worldwide.",
    url = "https://doi.org/10.1080/13683500.2011.585227",
    doi = "10.1080/13683500.2011.585227",
    openalex = "W2096847045",
    references = "doi101017s002531540501218x, doi101038137179b0"
}

Abstract There are widespread records of grouping behaviour in both adult and juvenile sharks and rays (Class Chondrichthyes, Subclass Elasmobranchii). Yet despite burgeoning descriptions of these events, many of the proximate and ultimate causes of group living in these top predators remain elusive. Given the documented negative anthropogenic effects on many shark populations globally, there is an increasing need to understand how behaviourally mediated grouping influences population distributions and abundance, and the role this plays in exacerbating vulnerability to fishing mortality. Here, we analyse group living in elasmobranchs: we describe our current understanding of the patterns, mechanisms and functions of both aggregation (where grouping is not driven by social mechanisms) and social grouping (where grouping is influenced by social interaction) and discuss some of the current methods used to study social behaviour in this taxa. In particular, social preferences in elasmobranchs have received relatively little attention. We propose that the study of shark aggregations may benefit from a more fine‐scale analytical approach offered by detailed exploration of social interactions using social network analysis. Better understanding of the frequency and longevity of social relations, in conjunction with current long‐term data on habitat use and site philopatry, will likely serve for a more informed approach to coastal and pelagic elasmobranch conservation initiatives.

@article{doi101111j14672979201100436x,
    author = "Jacoby, David and Croft, Darren P. and Sims, David",
    title = "Social behaviour in sharks and rays: analysis, patterns and implications for conservation",
    year = "2011",
    journal = "Fish and Fisheries",
    abstract = "Abstract There are widespread records of grouping behaviour in both adult and juvenile sharks and rays (Class Chondrichthyes, Subclass Elasmobranchii). Yet despite burgeoning descriptions of these events, many of the proximate and ultimate causes of group living in these top predators remain elusive. Given the documented negative anthropogenic effects on many shark populations globally, there is an increasing need to understand how behaviourally mediated grouping influences population distributions and abundance, and the role this plays in exacerbating vulnerability to fishing mortality. Here, we analyse group living in elasmobranchs: we describe our current understanding of the patterns, mechanisms and functions of both aggregation (where grouping is not driven by social mechanisms) and social grouping (where grouping is influenced by social interaction) and discuss some of the current methods used to study social behaviour in this taxa. In particular, social preferences in elasmobranchs have received relatively little attention. We propose that the study of shark aggregations may benefit from a more fine‐scale analytical approach offered by detailed exploration of social interactions using social network analysis. Better understanding of the frequency and longevity of social relations, in conjunction with current long‐term data on habitat use and site philopatry, will likely serve for a more informed approach to coastal and pelagic elasmobranch conservation initiatives.",
    url = "https://doi.org/10.1111/j.1467-2979.2011.00436.x",
    doi = "10.1111/j.1467-2979.2011.00436.x",
    openalex = "W2096842280",
    references = "doi1023071442530"
}

Reproductive biology and phylogeny of Chondrichthyes:, Reproductive biology and phylogeny of Chondrichthyes:, مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

@book{doi1012019781439856000,
    title = "Reproductive Biology and Phylogeny of Chondrichthyes",
    year = "2011",
    abstract = "Reproductive biology and phylogeny of Chondrichthyes:, Reproductive biology and phylogeny of Chondrichthyes:, مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی",
    url = "https://doi.org/10.1201/9781439856000",
    doi = "10.1201/9781439856000",
    openalex = "W3004270960"
}

Sharks are one of the most threatened groups of marine animals, as high exploitation rates coupled with low resilience to fishing pressure have resulted in population declines worldwide. Designing conservation strategies for this group depends on basic knowledge of the geographic distribution and diversity of known species. So far, this information has been fragmented and incomplete. Here, we have synthesized the first global shark diversity pattern from a new database of published sources, including all 507 species described at present, and have identified hotspots of shark species richness, functional diversity and endemicity from these data. We have evaluated the congruence of these diversity measures and demonstrate their potential use in setting priority areas for shark conservation. Our results show that shark diversity across all species peaks on the continental shelves and at mid-latitudes (30-40 degrees N and S). Global hotspots of species richness, functional diversity and endemicity were found off Japan, Taiwan, the East and West coasts of Australia, Southeast Africa, Southeast Brazil and Southeast USA. Moreover, some areas with low to moderate species richness such as Southern Australia, Angola, North Chile and Western Continental Europe stood out as places of high functional diversity. Finally, species affected by shark finning showed different patterns of diversity, with peaks closer to the Equator and a more oceanic distribution overall. Our results show that the global pattern of shark diversity is uniquely different from land, and other well-studied marine taxa, and may provide guidance for spatial approaches to shark conservation. However, similar to terrestrial ecosystems, protected areas based on hotspots of diversity and endemism alone would provide insufficient means for safeguarding the diverse functional roles that sharks play in marine ecosystems.

@article{doi101371journalpone0019356,
    author = "Lucifora, Luis O. and García, Verónica B. and Worm, Boris",
    title = "Global Diversity Hotspots and Conservation Priorities for Sharks",
    year = "2011",
    journal = "PLoS ONE",
    abstract = "Sharks are one of the most threatened groups of marine animals, as high exploitation rates coupled with low resilience to fishing pressure have resulted in population declines worldwide. Designing conservation strategies for this group depends on basic knowledge of the geographic distribution and diversity of known species. So far, this information has been fragmented and incomplete. Here, we have synthesized the first global shark diversity pattern from a new database of published sources, including all 507 species described at present, and have identified hotspots of shark species richness, functional diversity and endemicity from these data. We have evaluated the congruence of these diversity measures and demonstrate their potential use in setting priority areas for shark conservation. Our results show that shark diversity across all species peaks on the continental shelves and at mid-latitudes (30-40 degrees N and S). Global hotspots of species richness, functional diversity and endemicity were found off Japan, Taiwan, the East and West coasts of Australia, Southeast Africa, Southeast Brazil and Southeast USA. Moreover, some areas with low to moderate species richness such as Southern Australia, Angola, North Chile and Western Continental Europe stood out as places of high functional diversity. Finally, species affected by shark finning showed different patterns of diversity, with peaks closer to the Equator and a more oceanic distribution overall. Our results show that the global pattern of shark diversity is uniquely different from land, and other well-studied marine taxa, and may provide guidance for spatial approaches to shark conservation. However, similar to terrestrial ecosystems, protected areas based on hotspots of diversity and endemism alone would provide insufficient means for safeguarding the diverse functional roles that sharks play in marine ecosystems.",
    url = "https://doi.org/10.1371/journal.pone.0019356",
    doi = "10.1371/journal.pone.0019356",
    openalex = "W2046570447",
    references = "openalexw1511461941, openalexw3190442888"
}

The use of photography to discriminate between individuals in a population using natural markings or aberrations is increasingly being utilized to support field research on elasmobranchs. This non‐intrusive method has facilitated investigation of a wide variety of subjects including population composition, abundance estimates, residency and movement, demography and social behaviours. Here the first detailed review of photo‐identification as a research technique for sharks and rays is provided, and its assumptions, current applications and potential highlighted. The limitations and practical considerations of photographic studies are also investigated with recommendations on initial survey design and ongoing data collection using current technology. Future directions are also explored with an emphasis on a move towards standardized approaches and automated recognition programmes to facilitate global collaborative work.

@article{doi101111j10958649201203244x,
    author = "Marshall, Andrea D. and Pierce, Simon J.",
    title = "The use and abuse of photographic identification in sharks and rays",
    year = "2012",
    journal = "Journal of Fish Biology",
    abstract = "The use of photography to discriminate between individuals in a population using natural markings or aberrations is increasingly being utilized to support field research on elasmobranchs. This non‐intrusive method has facilitated investigation of a wide variety of subjects including population composition, abundance estimates, residency and movement, demography and social behaviours. Here the first detailed review of photo‐identification as a research technique for sharks and rays is provided, and its assumptions, current applications and potential highlighted. The limitations and practical considerations of photographic studies are also investigated with recommendations on initial survey design and ongoing data collection using current technology. Future directions are also explored with an emphasis on a move towards standardized approaches and automated recognition programmes to facilitate global collaborative work.",
    url = "https://doi.org/10.1111/j.1095-8649.2012.03244.x",
    doi = "10.1111/j.1095-8649.2012.03244.x",
    openalex = "W2073098723",
    references = "doi101023a1007656126281, doi101111j10958649201203264x"
}

Although the whale shark Rhincodon typus is the largest extant fish, it was not described until 1828 and by 1986 there were only 320 records of this species. Since then, growth in tourism and marine recreation globally has lead to a significant increase in the number of sightings and several areas with annual occurrences have been identified, spurring a surge of research on the species. Simultaneously, there was a great expansion in targeted R. typus fisheries to supply the Asian restaurant trade, as well as a largely un-quantified by-catch of the species in purse-seine tuna fisheries. Currently R. typus is listed by the IUCN as vulnerable, due mainly to the effects of targeted fishing in two areas. Photo-identification has shown that R. typus form seasonal size and sex segregated feeding aggregations and that a large proportion of fish in these aggregations are philopatric in the broadest sense, tending to return to, or remain near, a particular site. Somewhat conversely, satellite tracking studies have shown that fish from these aggregations can migrate at ocean-basin scales and genetic studies have, to date, found little graphic differentiation globally. Conservation approaches are now informed by observational and environmental studies that have provided insight into the feeding habits of the species and its preferred habitats. Notwithstanding these advances, there remain notable gaps in the knowledge of this species particularly with respect to the life history of neonates and adults who are not found in the feeding aggregations.

@article{doi101111j10958649201203252x,
    author = "Rowat, David and Brooks, Katie",
    title = "A review of the biology, fisheries and conservation of the whale shark Rhincodon typus",
    year = "2012",
    journal = "Journal of Fish Biology",
    abstract = "Although the whale shark Rhincodon typus is the largest extant fish, it was not described until 1828 and by 1986 there were only 320 records of this species. Since then, growth in tourism and marine recreation globally has lead to a significant increase in the number of sightings and several areas with annual occurrences have been identified, spurring a surge of research on the species. Simultaneously, there was a great expansion in targeted R. typus fisheries to supply the Asian restaurant trade, as well as a largely un-quantified by-catch of the species in purse-seine tuna fisheries. Currently R. typus is listed by the IUCN as vulnerable, due mainly to the effects of targeted fishing in two areas. Photo-identification has shown that R. typus form seasonal size and sex segregated feeding aggregations and that a large proportion of fish in these aggregations are philopatric in the broadest sense, tending to return to, or remain near, a particular site. Somewhat conversely, satellite tracking studies have shown that fish from these aggregations can migrate at ocean-basin scales and genetic studies have, to date, found little graphic differentiation globally. Conservation approaches are now informed by observational and environmental studies that have provided insight into the feeding habits of the species and its preferred habitats. Notwithstanding these advances, there remain notable gaps in the knowledge of this species particularly with respect to the life history of neonates and adults who are not found in the feeding aggregations.",
    url = "https://doi.org/10.1111/j.1095-8649.2012.03252.x",
    doi = "10.1111/j.1095-8649.2012.03252.x",
    openalex = "W2123459006",
    references = "doi101038164766a0, openalexw1511461941, openalexw3041320757"
}

Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective.

@article{doi101111j10958649201203265x,
    author = "Dudgeon, Christine L. and Blower, Dean C. and Broderick, Damien and Giles, Jenny and Holmes, Bonnie J. and Kashiwagi, Tom and Krück, Nils C. and Morgan, Jess A. T. and Tillett, Bree J. and Ovenden, Jennifer R.",
    title = "A review of the application of molecular genetics for fisheries management and conservation of sharks and rays",
    year = "2012",
    journal = "Journal of Fish Biology",
    abstract = "Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective.",
    url = "https://doi.org/10.1111/j.1095-8649.2012.03265.x",
    doi = "10.1111/j.1095-8649.2012.03265.x",
    openalex = "W1995327749",
    references = "doi101007s1064100691055, doi101038nature03959, doi101038nrg2626, doi101073pnas74125463, doi101093genetics16297, doi101093molbevmsq147, doi101093oso97801951358480010001, doi101098rspb20022218, doi101126science1058040, doi101126science2705235467, doi101126science2999980, doi107312nei92038, openalexw3041320757"
}

Conservation of top predators has been emphasized as essential in an ecosystem due to their role in trophic chain regulation. Optimizing conservation strategies for these endangered marine top predators requires direct estimates of breeding patterns and connectivity as these are essential to understanding the population dynamics. There have been some attempts to investigate breeding patterns of reef sharks from litter reconstruction using molecular analyses. However, direct fine-scale migrations of female sharks for parturition as well as connectivity at a medium scale like between islands remain mostly unknown. We used microsatellite DNA markers and a likelihood-based parentage analysis to determine breeding patterns of female blacktip reef sharks in Moorea (Society Islands, French Polynesia). Most females gave birth at their home island but some migrated to specific nursery areas outside the area they are attached to, sometimes going to another island 50 km away across deep ocean. Our analysis also revealed that females migrated to the same nursery for every birthing event. Many offspring showed a high level of inbreeding indicating an overall reduced population size, restricted movements and dispersal, or specific mating behaviour. Females represent the vectors that transport the genes at nursery grounds, and their fidelity should thus define reproductive units. As females seem to be philopatric, males could be the ones dispersing genes between populations. These results highlight the need to conserve coastal zones where female reef sharks seem to exhibit philopatry during the breeding season.

@article{doi101111mec12103,
    author = "Mourier, Johann and Planes, Serge",
    title = "Direct genetic evidence for reproductive philopatry and associated fine‐scale migrations in female blacktip reef sharks (Carcharhinus melanopterus) in French Polynesia",
    year = "2012",
    journal = "Molecular Ecology",
    abstract = "Conservation of top predators has been emphasized as essential in an ecosystem due to their role in trophic chain regulation. Optimizing conservation strategies for these endangered marine top predators requires direct estimates of breeding patterns and connectivity as these are essential to understanding the population dynamics. There have been some attempts to investigate breeding patterns of reef sharks from litter reconstruction using molecular analyses. However, direct fine-scale migrations of female sharks for parturition as well as connectivity at a medium scale like between islands remain mostly unknown. We used microsatellite DNA markers and a likelihood-based parentage analysis to determine breeding patterns of female blacktip reef sharks in Moorea (Society Islands, French Polynesia). Most females gave birth at their home island but some migrated to specific nursery areas outside the area they are attached to, sometimes going to another island 50 km away across deep ocean. Our analysis also revealed that females migrated to the same nursery for every birthing event. Many offspring showed a high level of inbreeding indicating an overall reduced population size, restricted movements and dispersal, or specific mating behaviour. Females represent the vectors that transport the genes at nursery grounds, and their fidelity should thus define reproductive units. As females seem to be philopatric, males could be the ones dispersing genes between populations. These results highlight the need to conserve coastal zones where female reef sharks seem to exhibit philopatry during the breeding season.",
    url = "https://doi.org/10.1111/mec.12103",
    doi = "10.1111/mec.12103",
    openalex = "W2054186850",
    references = "doi101023a1007656126281, doi101111j10958649201203265x"
}

In an effort to provide a framework for the accurate identification of elasmobranchs, driven in large part by the needs of parasitological studies, a comprehensive survey of DNA sequences derived from the mitochondrial NADH2 gene was conducted for elasmobranchs collected from around the world. Analysis was based on sequences derived from 4283 specimens representing an estimated 574 (of ∼1221) species (305 sharks, 269 batoids), each represented by 1 to 176 specimens, in 157 (of 193 described) elasmobranch genera in 56 (of 57 described) families of elasmobranchs (only Hypnidae was not represented). A total of 1921 (44.9%) of the samples were represented by vouchers and/or images available in an online host specimen database (http//elasmobranchs.tapewormdb.uconn.edu). A representative sequence for each of the 574 species identified in this survey, as well as an additional 11 sequences for problematic complexes, has been deposited in GenBank. Neighbor-joining analysis of the data revealed a substantial amount of previously undocumented genetic diversity in elasmobranchs, suggesting 79 potentially new taxa (38 sharks, 41 batoids). Within-species p-distance variation in NADH2-percent sequence divergence ranged from 0 to 2.12 with a mean of 0.27; within-genus p-distance variation ranged from 0.03 to 27.01, with a mean of 10.16. These values are roughly consistent with estimates from prior studies based on barcode COI sequences for elasmobranchs and fishes. While biogeographic influences have likely shaped the diversification of the entire group, the traces left by older influences tend to be overprinted by newer ones. As a result, the most clearly interpretable influences are those associated with recently diverged taxa. Among closely related elasmobranchs, four regions appear to be of particular importance: (1) the Atlantic Ocean, (2) Arabian Sea, Persian Gulf, and Red Sea, (3) Southeast Asia, and (4) Australia. Each of these regions has a substantial proportion of taxa that are genetically distinct from their closest relatives in other regions. These results suggest that great care should be taken in establishing the identities of elasmobranch hosts in parasitological studies. Furthermore, it is likely that many existing host records require confirmation.

@article{doi1012067541,
    author = "Naylor, Gavin J. P. and Caira, Janine N. and Jensen, Kirsten and Rosana, K. A. M. and White, William T. and Last, Peter R.",
    title = "A DNA Sequence–Based Approach To the Identification of Shark and Ray Species and Its Implications for Global Elasmobranch Diversity and Parasitology",
    year = "2012",
    journal = "Bulletin of the American Museum of Natural History",
    abstract = "In an effort to provide a framework for the accurate identification of elasmobranchs, driven in large part by the needs of parasitological studies, a comprehensive survey of DNA sequences derived from the mitochondrial NADH2 gene was conducted for elasmobranchs collected from around the world. Analysis was based on sequences derived from 4283 specimens representing an estimated 574 (of ∼1221) species (305 sharks, 269 batoids), each represented by 1 to 176 specimens, in 157 (of 193 described) elasmobranch genera in 56 (of 57 described) families of elasmobranchs (only Hypnidae was not represented). A total of 1921 (44.9\%) of the samples were represented by vouchers and/or images available in an online host specimen database (http//elasmobranchs.tapewormdb.uconn.edu). A representative sequence for each of the 574 species identified in this survey, as well as an additional 11 sequences for problematic complexes, has been deposited in GenBank. Neighbor-joining analysis of the data revealed a substantial amount of previously undocumented genetic diversity in elasmobranchs, suggesting 79 potentially new taxa (38 sharks, 41 batoids). Within-species p-distance variation in NADH2-percent sequence divergence ranged from 0 to 2.12 with a mean of 0.27; within-genus p-distance variation ranged from 0.03 to 27.01, with a mean of 10.16. These values are roughly consistent with estimates from prior studies based on barcode COI sequences for elasmobranchs and fishes. While biogeographic influences have likely shaped the diversification of the entire group, the traces left by older influences tend to be overprinted by newer ones. As a result, the most clearly interpretable influences are those associated with recently diverged taxa. Among closely related elasmobranchs, four regions appear to be of particular importance: (1) the Atlantic Ocean, (2) Arabian Sea, Persian Gulf, and Red Sea, (3) Southeast Asia, and (4) Australia. Each of these regions has a substantial proportion of taxa that are genetically distinct from their closest relatives in other regions. These results suggest that great care should be taken in establishing the identities of elasmobranch hosts in parasitological studies. Furthermore, it is likely that many existing host records require confirmation.",
    url = "https://doi.org/10.1206/754.1",
    doi = "10.1206/754.1",
    openalex = "W2158111203",
    references = "doi101093nqs5vi146318i, doi1023071447424"
}

Some identified diversity events were mentioned in previous works using alternative methods (Early Jurassic, mid-Cretaceous, K/T boundary and late Paleogene diversity drops), thus reinforcing the efficiency of the methodology presented here in inferring evolutionary events. Other events (Permian/Triassic, Early and Late Cretaceous diversifications; Triassic/Jurassic extinction) are newly identified. Relationships between these events and paleoenvironmental characteristics and other groups' evolutionary history are proposed.

@article{doi101371journalpone0044632,
    author = "Guinot, Guillaume and Adnet, Sylvain and Cappetta, Henri",
    title = "An Analytical Approach for Estimating Fossil Record and Diversification Events in Sharks, Skates and Rays",
    year = "2012",
    journal = "PLoS ONE",
    abstract = "Some identified diversity events were mentioned in previous works using alternative methods (Early Jurassic, mid-Cretaceous, K/T boundary and late Paleogene diversity drops), thus reinforcing the efficiency of the methodology presented here in inferring evolutionary events. Other events (Permian/Triassic, Early and Late Cretaceous diversifications; Triassic/Jurassic extinction) are newly identified. Relationships between these events and paleoenvironmental characteristics and other groups' evolutionary history are proposed.",
    url = "https://doi.org/10.1371/journal.pone.0044632",
    doi = "10.1371/journal.pone.0044632",
    openalex = "W2046826834",
    references = "doi104072rbp2005205, openalexw641496887"
}

BACKGROUND: Predators can impact ecosystems through trophic cascades such that differential patterns in habitat use can lead to spatiotemporal variation in top down forcing on community dynamics. Thus, improved understanding of predator movements is important for evaluating the potential ecosystem effects of their declines. METHODOLOGY/PRINCIPAL FINDINGS: We satellite-tagged an apex predator (bull sharks, Carcharhinus leucas) and a sympatric mesopredator (Atlantic tarpon, Megalops atlanticus) in southern Florida waters to describe their habitat use, abundance and movement patterns. We asked four questions: (1) How do the seasonal abundance patterns of bull sharks and tarpon compare? (2) How do the movement patterns of bull sharks and tarpon compare, and what proportion of time do their respective primary ranges overlap? (3) Do tarpon movement patterns (e.g., straight versus convoluted paths) and/or their rates of movement (ROM) differ in areas of low versus high bull shark abundance? and (4) Can any general conclusions be reached concerning whether tarpon may mitigate risk of predation by sharks when they are in areas of high bull shark abundance? CONCLUSIONS/SIGNIFICANCE: Despite similarities in diet, bull sharks and tarpon showed little overlap in habitat use. Bull shark abundance was high year-round, but peaked in winter; while tarpon abundance and fishery catches were highest in late spring. However, presence of the largest sharks (>230 cm) coincided with peak tarpon abundance. When moving over deep open waters (areas of high shark abundance and high food availability) tarpon maintained relatively high ROM in directed lines until reaching shallow structurally-complex areas. At such locations, tarpon exhibited slow tortuous movements over relatively long time periods indicative of foraging. Tarpon periodically concentrated up rivers, where tracked bull sharks were absent. We propose that tarpon trade-off energetic costs of both food assimilation and osmoregulation to reduce predation risk by bull sharks.

@article{doi101371journalpone0045958,
    author = "Hammerschlag, Neil and Luo, Jiangang and Irschick, Duncan J. and Ault, Jerald S.",
    title = "A Comparison of Spatial and Movement Patterns between Sympatric Predators: Bull Sharks (Carcharhinus leucas) and Atlantic Tarpon (Megalops atlanticus)",
    year = "2012",
    journal = "PLoS ONE",
    abstract = "BACKGROUND: Predators can impact ecosystems through trophic cascades such that differential patterns in habitat use can lead to spatiotemporal variation in top down forcing on community dynamics. Thus, improved understanding of predator movements is important for evaluating the potential ecosystem effects of their declines. METHODOLOGY/PRINCIPAL FINDINGS: We satellite-tagged an apex predator (bull sharks, Carcharhinus leucas) and a sympatric mesopredator (Atlantic tarpon, Megalops atlanticus) in southern Florida waters to describe their habitat use, abundance and movement patterns. We asked four questions: (1) How do the seasonal abundance patterns of bull sharks and tarpon compare? (2) How do the movement patterns of bull sharks and tarpon compare, and what proportion of time do their respective primary ranges overlap? (3) Do tarpon movement patterns (e.g., straight versus convoluted paths) and/or their rates of movement (ROM) differ in areas of low versus high bull shark abundance? and (4) Can any general conclusions be reached concerning whether tarpon may mitigate risk of predation by sharks when they are in areas of high bull shark abundance? CONCLUSIONS/SIGNIFICANCE: Despite similarities in diet, bull sharks and tarpon showed little overlap in habitat use. Bull shark abundance was high year-round, but peaked in winter; while tarpon abundance and fishery catches were highest in late spring. However, presence of the largest sharks (>230 cm) coincided with peak tarpon abundance. When moving over deep open waters (areas of high shark abundance and high food availability) tarpon maintained relatively high ROM in directed lines until reaching shallow structurally-complex areas. At such locations, tarpon exhibited slow tortuous movements over relatively long time periods indicative of foraging. Tarpon periodically concentrated up rivers, where tracked bull sharks were absent. We propose that tarpon trade-off energetic costs of both food assimilation and osmoregulation to reduce predation risk by bull sharks.",
    url = "https://doi.org/10.1371/journal.pone.0045958",
    doi = "10.1371/journal.pone.0045958",
    openalex = "W2105557897",
    references = "doi101080000284872011618352"
}

BACKGROUND: Despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. We present the first direct comparison of the use of natural versus artificial habitats for the bull shark, Carcharhinus leucas, an IUCN 'Near-threatened' species--one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults. Understanding the value of alternate artificial coastal habitats to the lifecycle of the bull shark is crucial for determining the impact of coastal development on this threatened but potentially dangerous species. METHODOLOGY/FINDINGS: We used longline surveys and long-term passive acoustic tracking of neonate and juvenile bull sharks to determine the ontogenetic value of natural and artificial habitats to bull sharks associated with the Nerang River and adjoining canals on the Gold Coast, Australia. Long-term movements of tagged sharks suggested a preference for the natural river over artificial habitat (canals). Neonates and juveniles spent the majority of their time in the upper tidal reaches of the Nerang River and undertook excursions into adjoining canals. Larger bull sharks ranged further and frequented the canals closer to the river mouth. CONCLUSIONS/SIGNIFICANCE: Our work suggests with increased destruction of natural habitats, artificial coastal habitat may become increasingly important to large juvenile bull sharks with associated risk of attack on humans. In this system, neonate and juvenile bull sharks utilised the natural and artificial habitats, but the latter was not the preferred habitat of neonates. The upper reaches of tidal rivers, often under significant modification pressure, serve as nursery sites for neonates. Analogous studies are needed in similar systems elsewhere to assess the spatial and temporal generality of this research.

@article{doi101371journalpone0049796,
    author = "Werry, Jonathan M. and Lee, Shing Yip and Lemckert, Charles and Otway, Nicholas M.",
    title = "Natural or Artificial? Habitat-Use by the Bull Shark, Carcharhinus leucas",
    year = "2012",
    journal = "PLoS ONE",
    abstract = "BACKGROUND: Despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. We present the first direct comparison of the use of natural versus artificial habitats for the bull shark, Carcharhinus leucas, an IUCN 'Near-threatened' species--one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults. Understanding the value of alternate artificial coastal habitats to the lifecycle of the bull shark is crucial for determining the impact of coastal development on this threatened but potentially dangerous species. METHODOLOGY/FINDINGS: We used longline surveys and long-term passive acoustic tracking of neonate and juvenile bull sharks to determine the ontogenetic value of natural and artificial habitats to bull sharks associated with the Nerang River and adjoining canals on the Gold Coast, Australia. Long-term movements of tagged sharks suggested a preference for the natural river over artificial habitat (canals). Neonates and juveniles spent the majority of their time in the upper tidal reaches of the Nerang River and undertook excursions into adjoining canals. Larger bull sharks ranged further and frequented the canals closer to the river mouth. CONCLUSIONS/SIGNIFICANCE: Our work suggests with increased destruction of natural habitats, artificial coastal habitat may become increasingly important to large juvenile bull sharks with associated risk of attack on humans. In this system, neonate and juvenile bull sharks utilised the natural and artificial habitats, but the latter was not the preferred habitat of neonates. The upper reaches of tidal rivers, often under significant modification pressure, serve as nursery sites for neonates. Analogous studies are needed in similar systems elsewhere to assess the spatial and temporal generality of this research.",
    url = "https://doi.org/10.1371/journal.pone.0049796",
    doi = "10.1371/journal.pone.0049796",
    openalex = "W1993357863",
    references = "doi101080000284872011618352"
}

Understanding how natural and anthropogenic drivers affect extant food webs is critical to predicting the impacts of climate change and habitat alterations on ecosystem dynamics. In the Florida Everglades, seasonal reductions in freshwater flow and precipitation lead to annual migrations of aquatic taxa from marsh habitats to deep-water refugia in estuaries. The timing and intensity of freshwater reductions, however, will be modified by ongoing ecosystem restoration and predicted climate change. Understanding the importance of seasonally pulsed resources to predators is critical to predicting the impacts of management and climate change on their populations. As with many large predators, however, it is difficult to determine to what extent predators like bull sharks (Carcharhinus leucas) in the coastal Everglades make use of prey pulses currently. We used passive acoustic telemetry to determine whether shark movements responded to the pulse of marsh prey. To investigate the possibility that sharks fed on marsh prey, we modelled the predicted dynamics of stable isotope values in bull shark blood and plasma under different assumptions of temporal variability in shark diets and physiological dynamics of tissue turnover and isotopic discrimination. Bull sharks increased their use of upstream channels during the late dry season, and although our previous work shows long-term specialization in the diets of sharks, stable isotope values suggested that some individuals adjusted their diets to take advantage of prey entering the system from the marsh, and as such this may be an important resource for the nursery. Restoration efforts are predicted to increase hydroperiods and marsh water levels, likely shifting the timing, duration and intensity of prey pulses, which could have negative consequences for the bull shark population and/or induce shifts in behaviour. Understanding the factors influencing the propensity to specialize or adopt more flexible trophic interactions will be an important step in fully understanding the ecological role of predators and how ecological roles may vary with environmental and anthropogenic changes.

@article{doi1011111365265612106,
    author = "Matich, Philip and Heithaus, Michael R.",
    title = "Multi‐tissue stable isotope analysis and acoustic telemetry reveal seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary",
    year = "2013",
    journal = "Journal of Animal Ecology",
    abstract = "Understanding how natural and anthropogenic drivers affect extant food webs is critical to predicting the impacts of climate change and habitat alterations on ecosystem dynamics. In the Florida Everglades, seasonal reductions in freshwater flow and precipitation lead to annual migrations of aquatic taxa from marsh habitats to deep-water refugia in estuaries. The timing and intensity of freshwater reductions, however, will be modified by ongoing ecosystem restoration and predicted climate change. Understanding the importance of seasonally pulsed resources to predators is critical to predicting the impacts of management and climate change on their populations. As with many large predators, however, it is difficult to determine to what extent predators like bull sharks (Carcharhinus leucas) in the coastal Everglades make use of prey pulses currently. We used passive acoustic telemetry to determine whether shark movements responded to the pulse of marsh prey. To investigate the possibility that sharks fed on marsh prey, we modelled the predicted dynamics of stable isotope values in bull shark blood and plasma under different assumptions of temporal variability in shark diets and physiological dynamics of tissue turnover and isotopic discrimination. Bull sharks increased their use of upstream channels during the late dry season, and although our previous work shows long-term specialization in the diets of sharks, stable isotope values suggested that some individuals adjusted their diets to take advantage of prey entering the system from the marsh, and as such this may be an important resource for the nursery. Restoration efforts are predicted to increase hydroperiods and marsh water levels, likely shifting the timing, duration and intensity of prey pulses, which could have negative consequences for the bull shark population and/or induce shifts in behaviour. Understanding the factors influencing the propensity to specialize or adopt more flexible trophic interactions will be an important step in fully understanding the ecological role of predators and how ecological roles may vary with environmental and anthropogenic changes.",
    url = "https://doi.org/10.1111/1365-2656.12106",
    doi = "10.1111/1365-2656.12106",
    openalex = "W2107179359",
    references = "doi101080000284872011618352, doi101111j10958649201203251x"
}

Abstract Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed (‘natal philopatry’), which would have important conservation implications. Genetic profiling of lemon sharks (N egaprion brevirostris) from 20 consecutive cohorts (1993–2012) at B imini, B ahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993–1997 cohorts returned to give birth 14–17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long‐term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators.

@article{doi101111mec12583,
    author = "Feldheim, Kevin A. and Gruber, Samuel H. and DiBattista, Joseph D. and Babcock, Elizabeth A. and Kessel, Steven T. and Hendry, Andrew P. and Pikitch, Ellen K. and Ashley, Mary V. and Chapman, Demian D.",
    title = "Two decades of genetic profiling yields first evidence of natal philopatry and long‐term fidelity to parturition sites in sharks",
    year = "2013",
    journal = "Molecular Ecology",
    abstract = "Abstract Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed (‘natal philopatry’), which would have important conservation implications. Genetic profiling of lemon sharks (N egaprion brevirostris) from 20 consecutive cohorts (1993–2012) at B imini, B ahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993–1997 cohorts returned to give birth 14–17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long‐term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators.",
    url = "https://doi.org/10.1111/mec.12583",
    doi = "10.1111/mec.12583",
    openalex = "W2154099412",
    references = "doi101111j10958649201203265x"
}

All 13 orders of chondrichthyan fishes occur in Taiwanese waters, representing 52 chondrichthyan families (31 shark, 19 batoid, 2 chimaeroid) and 98 genera (64 shark, 31 batoid, 3 chimaeroid). A total of 119 shark, 58 batoid, and 4 chimaera species may occur in the waters surrounding Taiwan, pending taxonomic resolution of some groups. Of the 34 nominally described species from Taiwan, 17 are currently considered valid. The majority of named species occurred during two peak periods in Taiwanese chondrichthyan research; the first between 1959-63, when 13 nominal species were described, of which 7 remain valid today, and a second peak period between 2003-13 when 9 nominal species were described, of which 6 remain valid. The overall species diversity of Taiwan's chondrichthyan fauna is comparable to that of other adjacent marine zoogeographic hotspots, e.g. Japan (126 shark, 75 batoid, 11 chimaeroid species) and the Philippines (81 shark, 46 batoid, 2 chimaeroid species). The Carcharhiniformes, Squaliformes, Myliobatiformes, and Rajiformes are the most dominant orders in terms of abundance and species-richness within this region. Each of these groups may increase in relative diversity with improved taxonomic resolution resulting from the incorporation of molecular tools and renewed morphological studies. Improved identification of Taiwan's chondrichthyan fauna will aid in developing better conservation and management practices.

@article{doi1011646zootaxa375213,
    author = "Ebert, David A. and Ho, Hsuan‐Ching and White, William T. and de Carvalho, Marcelo R.",
    title = "Introduction to the systematics and biodiversity of sharks, rays, and chimaeras (Chondrichthyes) of Taiwan",
    year = "2013",
    journal = "Zootaxa",
    abstract = "All 13 orders of chondrichthyan fishes occur in Taiwanese waters, representing 52 chondrichthyan families (31 shark, 19 batoid, 2 chimaeroid) and 98 genera (64 shark, 31 batoid, 3 chimaeroid). A total of 119 shark, 58 batoid, and 4 chimaera species may occur in the waters surrounding Taiwan, pending taxonomic resolution of some groups. Of the 34 nominally described species from Taiwan, 17 are currently considered valid. The majority of named species occurred during two peak periods in Taiwanese chondrichthyan research; the first between 1959-63, when 13 nominal species were described, of which 7 remain valid today, and a second peak period between 2003-13 when 9 nominal species were described, of which 6 remain valid. The overall species diversity of Taiwan's chondrichthyan fauna is comparable to that of other adjacent marine zoogeographic hotspots, e.g. Japan (126 shark, 75 batoid, 11 chimaeroid species) and the Philippines (81 shark, 46 batoid, 2 chimaeroid species). The Carcharhiniformes, Squaliformes, Myliobatiformes, and Rajiformes are the most dominant orders in terms of abundance and species-richness within this region. Each of these groups may increase in relative diversity with improved taxonomic resolution resulting from the incorporation of molecular tools and renewed morphological studies. Improved identification of Taiwan's chondrichthyan fauna will aid in developing better conservation and management practices.",
    url = "https://doi.org/10.11646/zootaxa.3752.1.3",
    doi = "10.11646/zootaxa.3752.1.3",
    openalex = "W2080115546",
    references = "doi101016s027843439900076x, doi101016s0967064503000110, doi101111j109636421926tb02228x, doi1011646zootaxa3752116, doi101643004585112001003021220co2, doi105281zenodo15921671, doi105479si00963801251289315, openalexw2230870765, openalexw571605905, openalexw632540735"
}

The late Miocene Gatun Formation of northern Panama contains a highly diverse and well sampled fossil marine assemblage that occupied a shallow-water embayment close to a purported connection between the Pacific and Atlantic (Caribbean) oceans. However, the diverse chondrichthyan fauna has been poorly documented. Based on recent field discoveries and further analysis of existing collections, the chondrichthyan fauna from this unit comprises at least 26 taxa, of which four species are extinct today. The remaining portion of the total chondrichthyan biodiversity has affinities with modern taxa and is therefore comprised of long-lived species. Based on known records of the modern geographic distribution range of the Gatun chondrichthyans, the fauna has mixed biogeographic affinities suggesting that around 10 million yr ago, a connection likely occurred between the Pacific Ocean and the Caribbean Sea. Given the known habitat preferences for modern chondrichthyans, the Gatun fauna was primarily adapted to shallow waters within the neritic zone. Finally, comparisons of Gatun dental measurements with other faunas suggest that many of the taxa have an abundance of small individuals, in agreement with previous studies that proposed this area as a paleonursery habitat for the species Carcharocles megalodon.

@article{doi10166612117,
    author = "Pimiento, Catalina and González-Barba, Gerardo and Ehret, Dana J. and Hendy, Austin and MacFadden, Bruce J. and Jaramillo, Carlos",
    title = "Sharks and rays (Chondrichthyes, Elasmobranchii) from the late Miocene Gatun Formation of Panama",
    year = "2013",
    journal = "Journal of Paleontology",
    abstract = "The late Miocene Gatun Formation of northern Panama contains a highly diverse and well sampled fossil marine assemblage that occupied a shallow-water embayment close to a purported connection between the Pacific and Atlantic (Caribbean) oceans. However, the diverse chondrichthyan fauna has been poorly documented. Based on recent field discoveries and further analysis of existing collections, the chondrichthyan fauna from this unit comprises at least 26 taxa, of which four species are extinct today. The remaining portion of the total chondrichthyan biodiversity has affinities with modern taxa and is therefore comprised of long-lived species. Based on known records of the modern geographic distribution range of the Gatun chondrichthyans, the fauna has mixed biogeographic affinities suggesting that around 10 million yr ago, a connection likely occurred between the Pacific Ocean and the Caribbean Sea. Given the known habitat preferences for modern chondrichthyans, the Gatun fauna was primarily adapted to shallow waters within the neritic zone. Finally, comparisons of Gatun dental measurements with other faunas suggest that many of the taxa have an abundance of small individuals, in agreement with previous studies that proposed this area as a paleonursery habitat for the species Carcharocles megalodon.",
    url = "https://doi.org/10.1666/12-117",
    doi = "10.1666/12-117",
    openalex = "W2069766731",
    references = "doi101016s0169534797897911, doi101038357153a0, doi101093icb172303, doi101643004585112001003021220co2, doi1023071437499, doi1023071447582, doi103354meps337287, doi105860choice496872, openalexw1273741486, openalexw570265017"
}

Sightings of planktivorous elasmobranchs at their coastal aggregation sites are often linked to biological, environmental and temporal variables. Many large planktivorous elasmobranchs are also globally threatened species, so it is necessary to try and separate population trends from environmentally driven, short-term fluctuations. We investigated the influence of environmental variables on sightings of 3 species of planktivorous elasmobranchs off Praia do Tofo, Mozambique: the reef manta ray Manta alfredi, giant manta ray M. birostris and whale shark Rhincodon typus. We used 8-(2003 to 2011) and 6-yr (2005 to 2011) logbook data for manta rays and whale sharks, respectively, and constructed a generalised linear model with animal sightings as the response. Predictors included temporal (year, month, time of day), biological (plankton categories), oceanographic (water temperature, time from high tide, current direction and strength and wave height) and celestial (moon illumination) indices. These predictors best fitted reef manta ray sightings, a coastal species with high residency, but less so for the wider-ranging giant manta rays and whale sharks. We found a significant decline in the standardised sightings time series for the reef manta ray (88%) and whale shark (79%), but not for the giant manta ray.

@article{doi103354meps10290,
    author = "Rohner, Christoph A. and Pierce, Simon J. and Marshall, Andrea D. and Weeks, Scarla and Bennett, M. B. and Richardson, Anthony J.",
    title = "Trends in sightings and environmental influences on a coastal aggregation of manta rays and whale sharks",
    year = "2013",
    journal = "Marine Ecology Progress Series",
    abstract = "Sightings of planktivorous elasmobranchs at their coastal aggregation sites are often linked to biological, environmental and temporal variables. Many large planktivorous elasmobranchs are also globally threatened species, so it is necessary to try and separate population trends from environmentally driven, short-term fluctuations. We investigated the influence of environmental variables on sightings of 3 species of planktivorous elasmobranchs off Praia do Tofo, Mozambique: the reef manta ray Manta alfredi, giant manta ray M. birostris and whale shark Rhincodon typus. We used 8-(2003 to 2011) and 6-yr (2005 to 2011) logbook data for manta rays and whale sharks, respectively, and constructed a generalised linear model with animal sightings as the response. Predictors included temporal (year, month, time of day), biological (plankton categories), oceanographic (water temperature, time from high tide, current direction and strength and wave height) and celestial (moon illumination) indices. These predictors best fitted reef manta ray sightings, a coastal species with high residency, but less so for the wider-ranging giant manta rays and whale sharks. We found a significant decline in the standardised sightings time series for the reef manta ray (88\%) and whale shark (79\%), but not for the giant manta ray.",
    url = "https://doi.org/10.3354/meps10290",
    doi = "10.3354/meps10290",
    openalex = "W2005562847",
    references = "doi101111j10958649201203264x"
}

Top predators and large-bodied megafauna are often the most affected elements of exploited ecosystems, both on land and in the sea; and the top-down control these predators exert on prey species can significantly alter community structure The loss of predation and the resultant indirect effects of mesopredator release and trophic cascades have resulted in widespread trophic downgrading of ecosystems For example, both the loss of wolves from Yellowstone National Park in the USA and declines in largebodied shark populations of the western North Atlantic Ocean have been reported to cause mesopredator release and trophic cascades Recently, much of the research focus has been on the response of prey to predators; here, we focus our attention on the ecological role of the predator. Despite some compelling and widely-cited case studies, our understanding of the dynamics of predators in regulating prey populations is still limited, yet predation is recognised as a key ecological and evolutionary process Particularly in the marine realm, gaining sufficient knowledge of large, highly mobile predators to define their roles is challenging. The widespread nature of these species makes them difficult to target, handle and experimentally manipulate for the purposes of research. Thus, defining the impacts of large marine predators is problematic.

@article{doi103354meps10597,
    author = "Heupel, Michelle R. and Knip, DM and Simpfendorfer, Colin A. and Dulvy, Nicholas K.",
    title = "Sizing up the ecological role of sharks as predators",
    year = "2013",
    journal = "Marine Ecology Progress Series",
    abstract = "Top predators and large-bodied megafauna are often the most affected elements of exploited ecosystems, both on land and in the sea; and the top-down control these predators exert on prey species can significantly alter community structure The loss of predation and the resultant indirect effects of mesopredator release and trophic cascades have resulted in widespread trophic downgrading of ecosystems For example, both the loss of wolves from Yellowstone National Park in the USA and declines in largebodied shark populations of the western North Atlantic Ocean have been reported to cause mesopredator release and trophic cascades Recently, much of the research focus has been on the response of prey to predators; here, we focus our attention on the ecological role of the predator. Despite some compelling and widely-cited case studies, our understanding of the dynamics of predators in regulating prey populations is still limited, yet predation is recognised as a key ecological and evolutionary process Particularly in the marine realm, gaining sufficient knowledge of large, highly mobile predators to define their roles is challenging. The widespread nature of these species makes them difficult to target, handle and experimentally manipulate for the purposes of research. Thus, defining the impacts of large marine predators is problematic.",
    url = "https://doi.org/10.3354/meps10597",
    doi = "10.3354/meps10597",
    openalex = "W2037340081",
    references = "doi101006jmsc19990489, doi101007bf00005044, doi101016jtree201303008, doi101111j13652656201001753x, doi1018900012965820020830480faatsp20co2"
}

Abstract Age and growth estimates for the Bull Shark Carcharhinus leucas were derived from 121 vertebral centra collected from Bull Sharks (59.1–223.5cm FL) between 1966 and 2010 in the western North Atlantic Ocean. Size at birth was confirmed with an additional 20 embryos (44.2–54.4cm FL). The maximum age based on vertebral band pair counts was 25 (184cm FL) and 27 (196cm FL) years for males and females, respectively. The logistic and Gompertz growth models fitted the size‐at‐age data best for males and females, respectively. Based on previously published estimates of length at maturity, males mature at 15–17years (176–185cm FL) and females at 15years (189cm FL). Bull Sharks in the western North Atlantic Ocean and the Gulf of Mexico have similar growth rates and reach similar sizes at age.

@article{doi101080000284872014892537,
    author = "Natanson, Lisa J. and Adams, Douglas H. and Winton, Megan V. and Maurer, Jasmine R.",
    title = "Age and Growth of the Bull Shark in the Western North Atlantic Ocean",
    year = "2014",
    journal = "Transactions of the American Fisheries Society",
    abstract = "Abstract Age and growth estimates for the Bull Shark Carcharhinus leucas were derived from 121 vertebral centra collected from Bull Sharks (59.1–223.5cm FL) between 1966 and 2010 in the western North Atlantic Ocean. Size at birth was confirmed with an additional 20 embryos (44.2–54.4cm FL). The maximum age based on vertebral band pair counts was 25 (184cm FL) and 27 (196cm FL) years for males and females, respectively. The logistic and Gompertz growth models fitted the size‐at‐age data best for males and females, respectively. Based on previously published estimates of length at maturity, males mature at 15–17years (176–185cm FL) and females at 15years (189cm FL). Bull Sharks in the western North Atlantic Ocean and the Gulf of Mexico have similar growth rates and reach similar sizes at age.",
    url = "https://doi.org/10.1080/00028487.2014.892537",
    doi = "10.1080/00028487.2014.892537",
    openalex = "W2022853412",
    references = "doi101080000284872011618352, doi101139f95038"
}

Abstract The successful management of shark populations requires juvenile recruitment success. Thus, conservation initiatives now strive to include the protection of areas used by pre‐adult sharks in order to promote juvenile survivorship. Many shark species use inshore areas for early life stages; however, species often segregate within sites to reduce competition. Using a fisheries‐independent gillnet survey from the Northern Gulf of Mexico (2000–2010) we describe distribution patterns and preferred habitat features of the juveniles of six shark species. Our results suggest that multiple shark species concurrently use the area for early life stages and although they overlap, they exhibit distinct habitat preferences characterized by physical variables. Habitat suitability models suggest that temperature, depth, and salinity are the important factors driving juvenile shark occurrence. Within each site, across the sampled range of physical characteristics, blacktip shark (Carcharhinus limbatus) preferred higher temperature (>30 °C) and mid‐depth (~5.5 m); bonnethead shark (Sphyrna tiburo) preferred higher temperature (>30 °C) and mid‐salinity (30–35 PSU), finetooth shark (Carcharhinus isodon) preferred low salinity (30 °C) and salinity (>35 PSU), Atlantic sharpnose shark (Rhizoprionodon terraenovae) preferred high temperature (>30 °C) and deep water (>6 m), and spinner shark (Carcharhinus brevipinna) preferred deep water (>8 m) and high temperature (>30 °C). The other investigated factors, including year, month, latitude, longitude, bottom type, inlet distance, coastline and human coast were not influential for any species. Combining habitat preferences with the sampled environmental characteristics, we predicted habitat suitability throughout the four sites for which physical characteristics were sampled. Habitat suitability surfaces highlight the differences in habitat use between and within sites. This work provides important insight into the habitat ecology of juvenile shark populations, which can be used to better manage these species and protect critical habitat.

@article{doi101111maec12151,
    author = "Ward‐Paige, Christine A. and Britten, Gregory L. and Bethea, Dana M. and Carlson, John K.",
    title = "Characterizing and predicting essential habitat features for juvenile coastal sharks",
    year = "2014",
    journal = "Marine Ecology",
    abstract = "Abstract The successful management of shark populations requires juvenile recruitment success. Thus, conservation initiatives now strive to include the protection of areas used by pre‐adult sharks in order to promote juvenile survivorship. Many shark species use inshore areas for early life stages; however, species often segregate within sites to reduce competition. Using a fisheries‐independent gillnet survey from the Northern Gulf of Mexico (2000–2010) we describe distribution patterns and preferred habitat features of the juveniles of six shark species. Our results suggest that multiple shark species concurrently use the area for early life stages and although they overlap, they exhibit distinct habitat preferences characterized by physical variables. Habitat suitability models suggest that temperature, depth, and salinity are the important factors driving juvenile shark occurrence. Within each site, across the sampled range of physical characteristics, blacktip shark (Carcharhinus limbatus) preferred higher temperature (>30 °C) and mid‐depth (\textasciitilde 5.5 m); bonnethead shark (Sphyrna tiburo) preferred higher temperature (>30 °C) and mid‐salinity (30–35 PSU), finetooth shark (Carcharhinus isodon) preferred low salinity (30 °C) and salinity (>35 PSU), Atlantic sharpnose shark (Rhizoprionodon terraenovae) preferred high temperature (>30 °C) and deep water (>6 m), and spinner shark (Carcharhinus brevipinna) preferred deep water (>8 m) and high temperature (>30 °C). The other investigated factors, including year, month, latitude, longitude, bottom type, inlet distance, coastline and human coast were not influential for any species. Combining habitat preferences with the sampled environmental characteristics, we predicted habitat suitability throughout the four sites for which physical characteristics were sampled. Habitat suitability surfaces highlight the differences in habitat use between and within sites. This work provides important insight into the habitat ecology of juvenile shark populations, which can be used to better manage these species and protect critical habitat.",
    url = "https://doi.org/10.1111/maec.12151",
    doi = "10.1111/maec.12151",
    openalex = "W2036382198",
    references = "doi101071mf03023"
}

Living vertebrate diversity comprises hagfishes and lampreys (Cyclostomata), elasmobranchs and holocephalans (Chondrichthyes), and bony fish which include tetrapods (Osteichthyes). Based on dissections and an extensive comparative analysis, we provide an updated overview of the anatomy, homologies and evolution of cyclostome and chondrichthyan cephalic muscles, with osteichthyans as primary comparative taxa. The analysis also infers plesiomorphic conditions for vertebrates and gnathostomes. We follow a uniform myological terminology for the Gnathostomata to demonstrate that the last common ancestor of extant vertebrates probably had a single intermandibularis and other mandibular muscles (labial muscles), some constrictores hyoidei and branchiales, and epibranchial and hypobranchial muscle sheets. The division of the cucullaris into levatores arcuum branchialium and protractor pectoralis is an osteichthyan synapomorphy and reflects an evolutionary trend towards a greater separation between the head and pectoral girdle that culminated in the formation of the tetrapod neck. Hence, this paper addresses a long-standing, central issue regarding vertebrate comparative anatomy. It thus provides a valuable basis for future evolutionary, developmental and functional studies of vertebrates and/or of specific vertebrate subgroups/model organisms. © 2014 The Linnean Society of London

@article{doi101111zoj12186,
    author = "Ziermann, Janine M. and Miyashita, Tetsuto and Diogo, Rui",
    title = "Cephalic muscles of Cyclostomes (hagfishes and lampreys) and Chondrichthyes (sharks, rays and holocephalans): comparative anatomy and early evolution of the vertebrate head muscles",
    year = "2014",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "Living vertebrate diversity comprises hagfishes and lampreys (Cyclostomata), elasmobranchs and holocephalans (Chondrichthyes), and bony fish which include tetrapods (Osteichthyes). Based on dissections and an extensive comparative analysis, we provide an updated overview of the anatomy, homologies and evolution of cyclostome and chondrichthyan cephalic muscles, with osteichthyans as primary comparative taxa. The analysis also infers plesiomorphic conditions for vertebrates and gnathostomes. We follow a uniform myological terminology for the Gnathostomata to demonstrate that the last common ancestor of extant vertebrates probably had a single intermandibularis and other mandibular muscles (labial muscles), some constrictores hyoidei and branchiales, and epibranchial and hypobranchial muscle sheets. The division of the cucullaris into levatores arcuum branchialium and protractor pectoralis is an osteichthyan synapomorphy and reflects an evolutionary trend towards a greater separation between the head and pectoral girdle that culminated in the formation of the tetrapod neck. Hence, this paper addresses a long-standing, central issue regarding vertebrate comparative anatomy. It thus provides a valuable basis for future evolutionary, developmental and functional studies of vertebrates and/or of specific vertebrate subgroups/model organisms. © 2014 The Linnean Society of London",
    url = "https://doi.org/10.1111/zoj.12186",
    doi = "10.1111/zoj.12186",
    openalex = "W2108196974",
    references = "doi1010079783642455322, doi1010160012160683903184, doi101016s0092867400801890, doi101038nature04336, doi101093oso97801985404720010001, doi101126science2204594268, doi1023072413058, doi105860choice340925, doi105962bhltitle82144, openalexw70084438"
}

The overexploitation of sharks has become a global environmental issue in need of a comprehensive and multifaceted management response. Tracking studies are beginning to elucidate how shark movements shape the internal dynamics and structure of populations, which determine the most appropriate scale of these management efforts. Tracked sharks frequently either remain in a restricted geographic area for an extended period of time (residency) or return to a previously resided-in area after making long-distance movements (site fidelity). Genetic studies have shown that some individuals of certain species preferentially return to their exact birthplaces (natal philopatry) or birth regions (regional philopatry) for either parturition or mating, even though they make long-distance movements that would allow them to breed elsewhere. More than 80 peer-reviewed articles, constituting the majority of published shark tracking and population genetic studies, provide evidence of at least one of these behaviors in a combined 31 shark species from six of the eight extant orders. Residency, site fidelity, and philopatry can alone or in combination structure many coastal shark populations on finer geographic scales than expected based on their potential for dispersal. This information should therefore be used to scale and inform assessment, management, and conservation activities intended to restore depleted shark populations.

@article{doi101146annurevmarine010814015730,
    author = "Chapman, Demian D. and Feldheim, Kevin A. and Papastamatiou, Yannis P. and Hueter, Robert E.",
    title = "There and Back Again: A Review of Residency and Return Migrations in Sharks, with Implications for Population Structure and Management",
    year = "2014",
    journal = "Annual Review of Marine Science",
    abstract = "The overexploitation of sharks has become a global environmental issue in need of a comprehensive and multifaceted management response. Tracking studies are beginning to elucidate how shark movements shape the internal dynamics and structure of populations, which determine the most appropriate scale of these management efforts. Tracked sharks frequently either remain in a restricted geographic area for an extended period of time (residency) or return to a previously resided-in area after making long-distance movements (site fidelity). Genetic studies have shown that some individuals of certain species preferentially return to their exact birthplaces (natal philopatry) or birth regions (regional philopatry) for either parturition or mating, even though they make long-distance movements that would allow them to breed elsewhere. More than 80 peer-reviewed articles, constituting the majority of published shark tracking and population genetic studies, provide evidence of at least one of these behaviors in a combined 31 shark species from six of the eight extant orders. Residency, site fidelity, and philopatry can alone or in combination structure many coastal shark populations on finer geographic scales than expected based on their potential for dispersal. This information should therefore be used to scale and inform assessment, management, and conservation activities intended to restore depleted shark populations.",
    url = "https://doi.org/10.1146/annurev-marine-010814-015730",
    doi = "10.1146/annurev-marine-010814-015730",
    openalex = "W2119470225",
    references = "doi101111j10958649201203251x, doi101111j10958649201203265x"
}

The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery. DOI: http://dx.doi.org/10.7554/eLife.00590.001.

@article{doi107554elife00590,
    author = "Dulvy, Nicholas K. and Fowler, Sarah and Musick, John A. and Cavanagh, Rachel D. and Kyne, Peter M. and Harrison, Lucy R. and Carlson, John K. and Davidson, Lindsay N. K. and Fordham, Sonja V. and Francis, Malcolm P. and Pollock, Caroline M. and Simpfendorfer, Colin A. and Burgess, George H. and Carpenter, Kent E. and Compagno, Leonard J. V. and Ebert, David A. and Gibson, Claudine and Heupel, Michelle R. and Livingstone, Suzanne R. and Sanciangco, Jonnell C. and Stevens, John D. and Valenti, Sarah and White, William T.",
    title = "Extinction risk and conservation of the world’s sharks and rays",
    year = "2014",
    journal = "eLife",
    abstract = "The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery. DOI: http://dx.doi.org/10.7554/eLife.00590.001.",
    url = "https://doi.org/10.7554/elife.00590",
    doi = "10.7554/elife.00590",
    openalex = "W2105316344",
    references = "doi101017s0376892909990191, doi101111j13652486200902128x, doi101111j15231739200801044x, doi101126science1103538, doi101126science1187512"
}

Background. The directed harvest and global trade in the gill plates of mantas, and devil rays, has led to increased fishing pressure and steep population declines in some locations. The slow life history, particularly of the manta rays, is cited as a key reason why such species have little capacity to withstand directed fisheries. Here, we place their life history and demography within the context of other sharks and rays. Methods. Despite the limited availability of data, we use life history theory and comparative analysis to estimate the intrinsic risk of extinction (as indexed by the maximum intrinsic rate of population increase r max) for a typical generic manta ray using a variant of the classic Euler-Lotka demographic model. This model requires only three traits to calculate the maximum intrinsic population growth rate r max: von Bertalanffy growth rate, annual pup production and age at maturity. To account for the uncertainty in life history parameters, we created plausible parameter ranges and propagate these uncertainties through the model to calculate a distribution of the plausible range of r max values. Results. The maximum population growth rate r max of manta ray is most sensitive to the length of the reproductive cycle, and the median r max of 0.116 year(-1) 95th percentile [0.089-0.139] is one of the lowest known of the 106 sharks and rays for which we have comparable demographic information. Discussion. In common with other unprotected, unmanaged, high-value large-bodied sharks and rays the combination of very low population growth rates of manta rays, combined with the high value of their gill rakers and the international nature of trade, is highly likely to lead to rapid depletion and potential local extinction unless a rapid conservation management response occurs worldwide. Furthermore, we show that it is possible to derive important insights into the demography extinction risk of data-poor species using well-established life history theory.

@article{doi107717peerj400,
    author = "Dulvy, Nicholas K. and Pardo, Sebastián A. and Simpfendorfer, Colin A. and Carlson, John K.",
    title = "Diagnosing the dangerous demography of manta rays using life history theory",
    year = "2014",
    journal = "PeerJ",
    abstract = "Background. The directed harvest and global trade in the gill plates of mantas, and devil rays, has led to increased fishing pressure and steep population declines in some locations. The slow life history, particularly of the manta rays, is cited as a key reason why such species have little capacity to withstand directed fisheries. Here, we place their life history and demography within the context of other sharks and rays. Methods. Despite the limited availability of data, we use life history theory and comparative analysis to estimate the intrinsic risk of extinction (as indexed by the maximum intrinsic rate of population increase r max) for a typical generic manta ray using a variant of the classic Euler-Lotka demographic model. This model requires only three traits to calculate the maximum intrinsic population growth rate r max: von Bertalanffy growth rate, annual pup production and age at maturity. To account for the uncertainty in life history parameters, we created plausible parameter ranges and propagate these uncertainties through the model to calculate a distribution of the plausible range of r max values. Results. The maximum population growth rate r max of manta ray is most sensitive to the length of the reproductive cycle, and the median r max of 0.116 year(-1) 95th percentile [0.089-0.139] is one of the lowest known of the 106 sharks and rays for which we have comparable demographic information. Discussion. In common with other unprotected, unmanaged, high-value large-bodied sharks and rays the combination of very low population growth rates of manta rays, combined with the high value of their gill rakers and the international nature of trade, is highly likely to lead to rapid depletion and potential local extinction unless a rapid conservation management response occurs worldwide. Furthermore, we show that it is possible to derive important insights into the demography extinction risk of data-poor species using well-established life history theory.",
    url = "https://doi.org/10.7717/peerj.400",
    doi = "10.7717/peerj.400",
    openalex = "W1981950770",
    references = "doi101007s1064100521365, doi101017s0376892909990191, doi101111j10958649201203264x"
}

@article{doi101016jmarpol201412017,
    author = "Oliver, Shelby and Braccini, Matías and Newman, Stephen J. and Harvey, Euan S.",
    title = "Global patterns in the bycatch of sharks and rays",
    year = "2015",
    journal = "Marine Policy",
    url = "https://doi.org/10.1016/j.marpol.2014.12.017",
    doi = "10.1016/j.marpol.2014.12.017",
    openalex = "W1973521198",
    references = "doi101017s0376892909990191"
}

is a relatively long-lived species with a widely distributed fossil record, we further used this study system to provide a deep-time perspective to the understanding of the body-size trends of marine apex predators. For instance, our results suggest that (1) a selective pressure in predatory sharks for consuming a broader range of prey may favor larger individuals and produce left-skewed distributions on a geologic time scale; (2) body-size variations in cosmopolitan apex marine predators may depend on their interactions with geographically discrete communities; and (3) the inherent characteristics of shark species can produce stable sizes over geologic time, regardless of the size trends of their lineages.

@article{doi101017pab201516,
    author = "Pimiento, Catalina and Balk, Meghan A.",
    title = "Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators",
    year = "2015",
    journal = "Paleobiology",
    abstract = "is a relatively long-lived species with a widely distributed fossil record, we further used this study system to provide a deep-time perspective to the understanding of the body-size trends of marine apex predators. For instance, our results suggest that (1) a selective pressure in predatory sharks for consuming a broader range of prey may favor larger individuals and produce left-skewed distributions on a geologic time scale; (2) body-size variations in cosmopolitan apex marine predators may depend on their interactions with geographically discrete communities; and (3) the inherent characteristics of shark species can produce stable sizes over geologic time, regardless of the size trends of their lineages.",
    url = "https://doi.org/10.1017/pab.2015.16",
    doi = "10.1017/pab.2015.16",
    openalex = "W2129162634",
    references = "doi10166612117"
}

Sex-biased dispersal is expected to homogenize nuclear genetic variation relative to variation in genetic material inherited through the philopatric sex. When site fidelity occurs across a heterogeneous environment, local selective regimes may alter this pattern. We assessed spatial patterns of variation in nuclear-encoded, single nucleotide polymorphisms (SNPs) and sequences of the mitochondrial control region in bonnethead sharks (Sphyrna tiburo), a species thought to exhibit female philopatry, collected from summer habitats used for gestation. Geographic patterns of mtDNA haplotypes and putatively neutral SNPs confirmed female philopatry and male-mediated gene flow along the northeastern coast of the Gulf of Mexico. A total of 30 outlier SNP loci were identified; alleles at over half of these loci exhibited signatures of latitude-associated selection. Our results indicate that in species with sex-biased dispersal, philopatry can facilitate sorting of locally adaptive variation, with the dispersing sex facilitating movement of potentially adaptive variation among locations and environments.

@article{doi101111mec13441,
    author = "Portnoy, David S. and Puritz, J. B. and Hollenbeck, Christopher M. and Gelsleichter, Jim and Chapman, Demian D. and Gold, John R.",
    title = "Selection and sex‐biased dispersal in a coastal shark: the influence of philopatry on adaptive variation",
    year = "2015",
    journal = "Molecular Ecology",
    abstract = "Sex-biased dispersal is expected to homogenize nuclear genetic variation relative to variation in genetic material inherited through the philopatric sex. When site fidelity occurs across a heterogeneous environment, local selective regimes may alter this pattern. We assessed spatial patterns of variation in nuclear-encoded, single nucleotide polymorphisms (SNPs) and sequences of the mitochondrial control region in bonnethead sharks (Sphyrna tiburo), a species thought to exhibit female philopatry, collected from summer habitats used for gestation. Geographic patterns of mtDNA haplotypes and putatively neutral SNPs confirmed female philopatry and male-mediated gene flow along the northeastern coast of the Gulf of Mexico. A total of 30 outlier SNP loci were identified; alleles at over half of these loci exhibited signatures of latitude-associated selection. Our results indicate that in species with sex-biased dispersal, philopatry can facilitate sorting of locally adaptive variation, with the dispersing sex facilitating movement of potentially adaptive variation among locations and environments.",
    url = "https://doi.org/10.1111/mec.13441",
    doi = "10.1111/mec.13441",
    openalex = "W2121676338",
    references = "doi101071mf03023"
}

An 829-bp fragment of the NADH dehydrogenase subunit 2 (NADH2) gene was used to assess the taxonomic status of 1487 elasmobranch specimens, representing 52 putative species. Strong evidence was found for the existence of an undescribed Echinorhinus species and for cryptic speciation within Rhynchobatus djiddensis. The results also provide strong molecular support for the existence of two previously reported, but undescribed, guitarfish species. Potential, but less conclusive, cryptic lineage diversification was also noted in Carcharhinus leucas, Loxodon macrorhinus, Iago omanensis and Gymnura poecilura. A complex situation was found in the genus Himantura, with potentially three distinct lineages evident, one of which is probably an undescribed species, in the H. gerrardi complex. One dasyatid specimen could not be identified, but appears to be closely related to Dasyatis ushiei, while Himantura leoparda and Carcharhinus longimanus are reported from Oman for the first time. The results of the present study also reinforce previously reported geographical divisions within certain putative species, which has important implications for fishery management and conservation. © 2015 The Linnean Society of London

@article{doi101111zoj12309,
    author = "Henderson, Aaron C. and Reeve, Alan J. and Jabado, Rima W. and Naylor, Gavin J. P.",
    title = "Taxonomic assessment of sharks, rays and guitarfishes (Chondrichthyes: Elasmobranchii) from south-eastern Arabia, using the NADH dehydrogenase subunit 2 (NADH2) gene",
    year = "2015",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "An 829-bp fragment of the NADH dehydrogenase subunit 2 (NADH2) gene was used to assess the taxonomic status of 1487 elasmobranch specimens, representing 52 putative species. Strong evidence was found for the existence of an undescribed Echinorhinus species and for cryptic speciation within Rhynchobatus djiddensis. The results also provide strong molecular support for the existence of two previously reported, but undescribed, guitarfish species. Potential, but less conclusive, cryptic lineage diversification was also noted in Carcharhinus leucas, Loxodon macrorhinus, Iago omanensis and Gymnura poecilura. A complex situation was found in the genus Himantura, with potentially three distinct lineages evident, one of which is probably an undescribed species, in the H. gerrardi complex. One dasyatid specimen could not be identified, but appears to be closely related to Dasyatis ushiei, while Himantura leoparda and Carcharhinus longimanus are reported from Oman for the first time. The results of the present study also reinforce previously reported geographical divisions within certain putative species, which has important implications for fishery management and conservation. © 2015 The Linnean Society of London",
    url = "https://doi.org/10.1111/zoj.12309",
    doi = "10.1111/zoj.12309",
    openalex = "W1870784066",
    references = "doi1012019781439856000, doi101371journalpone0036479"
}

The sister-clade to non-luminous Squalidae comprises five families. The presence of photophores is reported for extant members of three out of these five families based on results of this study, i.e. Lantern sharks (Etmopteridae), Kitefin sharks (Dalatiidae) and Sleeper sharks (Somniosidae). Our results suggest that the origin of luminous organs arose during the rapid diversification event that gave rise to the extant Squaliform families. These inferences are consistent with the idea of diversification of Squaliform sharks being associated with the emergence of new deep-sea habitats in the Lower Cretaceous, which may have been facilitated by the evolution of bioluminescence.

@article{doi101186s1286201504466,
    author = "Straube, Nicolas and Li, Chenhong and Claes, Julien M. and Corrigan, Shannon and Naylor, Gavin J. P.",
    title = "Molecular phylogeny of Squaliformes and first occurrence of bioluminescence in sharks",
    year = "2015",
    journal = "BMC Evolutionary Biology",
    abstract = "The sister-clade to non-luminous Squalidae comprises five families. The presence of photophores is reported for extant members of three out of these five families based on results of this study, i.e. Lantern sharks (Etmopteridae), Kitefin sharks (Dalatiidae) and Sleeper sharks (Somniosidae). Our results suggest that the origin of luminous organs arose during the rapid diversification event that gave rise to the extant Squaliform families. These inferences are consistent with the idea of diversification of Squaliform sharks being associated with the emergence of new deep-sea habitats in the Lower Cretaceous, which may have been facilitated by the evolution of bioluminescence.",
    url = "https://doi.org/10.1186/s12862-015-0446-6",
    doi = "10.1186/s12862-015-0446-6",
    openalex = "W1946645538",
    references = "doi101007s1312701100560, doi101038srep01308, doi101038srep04328, doi101093bioinformaticsbtm538, doi101093bioinformaticsbtu033, doi101093molbevmss020, doi101093nargkf436, doi101093nargki198, doi101111j10958649201203245x, doi101186147121487214, doi101371journalpbio0040088, doi1014806ej171200, openalexw570265017"
}

Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the general plesiomorphic vertebrate dental condition.

@article{doi101371journalpone0122553,
    author = "Underwood, Charlie J. and Johanson, Zerina and Welten, Monique and Metscher, Brian and Rasch, Liam J. and Fraser, Gareth J. and Smith, Moya Meredith",
    title = "Development and Evolution of Dentition Pattern and Tooth Order in the Skates And Rays (Batoidea; Chondrichthyes)",
    year = "2015",
    journal = "PLoS ONE",
    abstract = "Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the general plesiomorphic vertebrate dental condition.",
    url = "https://doi.org/10.1371/journal.pone.0122553",
    doi = "10.1371/journal.pone.0122553",
    openalex = "W2156417447",
    references = "doi101111j10958649201203245x, openalexw641496887"
}

Rays are among the largest fishes and evolved from shark-like ancestors nearly 200 million years ago. They share with sharks many life history traits: all species are carnivores or scavengers; all reproduce by internal fertilisation; and all have similar morphological and anatomical characteristics, such as skeletons built of cartilage. Rays of the World is the first complete pictorial atlas of the world’s ray fauna and includes information on many species only recently discovered by scientists while undertaking research for the book. It includes all 26 families and 633 valid named species of rays, but additional undescribed species exist for many groups. Rays of the World features a unique collection of paintings of all living species by Australian natural history artist Lindsay Marshall, compiled as part of a multinational research initiative, the Chondrichthyan Tree of Life Project. Images sourced from around the planet were used by the artist to illustrate the fauna. This comprehensive overview of the world’s ray fauna summarises information such as general identifying features and distributional information about these iconic, but surprisingly poorly known, fishes. It will enable readers to gain a better understanding of the rich diversity of rays and promote wider public interest in the group. Rays of the World is an ideal reference for a wide range of readers, including conservationists, fishery managers, scientists, fishers, divers, students and book collectors.

@book{doi1010719780643109148,
    title = "Rays of the World",
    year = "2016",
    booktitle = "CSIRO Publishing eBooks",
    abstract = "Rays are among the largest fishes and evolved from shark-like ancestors nearly 200 million years ago. They share with sharks many life history traits: all species are carnivores or scavengers; all reproduce by internal fertilisation; and all have similar morphological and anatomical characteristics, such as skeletons built of cartilage. Rays of the World is the first complete pictorial atlas of the world’s ray fauna and includes information on many species only recently discovered by scientists while undertaking research for the book. It includes all 26 families and 633 valid named species of rays, but additional undescribed species exist for many groups. Rays of the World features a unique collection of paintings of all living species by Australian natural history artist Lindsay Marshall, compiled as part of a multinational research initiative, the Chondrichthyan Tree of Life Project. Images sourced from around the planet were used by the artist to illustrate the fauna. This comprehensive overview of the world’s ray fauna summarises information such as general identifying features and distributional information about these iconic, but surprisingly poorly known, fishes. It will enable readers to gain a better understanding of the rich diversity of rays and promote wider public interest in the group. Rays of the World is an ideal reference for a wide range of readers, including conservationists, fishery managers, scientists, fishers, divers, students and book collectors.",
    url = "https://doi.org/10.1071/9780643109148",
    doi = "10.1071/9780643109148",
    openalex = "W2514660842"
}

An annotated checklist of the chondrichthyan fishes (sharks, batoids and chimaeras) of the world is presented. As of 7 November 2015, the number of species totals 1188, comprising 16 orders, 61 families and 199 genera. The checklist includes nine orders, 34 families, 105 genera and 509 species of sharks; six orders, 24 families, 88 genera and 630 species of batoids (skates and rays); one order, three families, six genera and 49 species of holocephalans (chimaeras). The most speciose shark orders are the Carcharhiniformes with 284 species, followed by the Squaliformes with 119. The most species-rich batoid orders are the Rajiformes with 285 species and the Myliobatiformes with 210. This checklist represents the first global checklist of chondrichthyans to include information on maximum size, geographic and depth distributions, as well as comments on taxonomically problematic species and recent and regularly overlooked synonymizations. Furthermore, a detailed analysis of the biogeographical diversity of the species across 10 major areas of occurrence is given, including updated figures for previously published hotspots of chondrichthyan biodiversity, providing the detailed numbers of chondrichthyan species per major area, and revealing centres of distribution for several taxa.

@article{doi101111jfb12874,
    author = "Weigmann, Simon",
    title = "Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeographical diversity",
    year = "2016",
    journal = "Journal of Fish Biology",
    abstract = "An annotated checklist of the chondrichthyan fishes (sharks, batoids and chimaeras) of the world is presented. As of 7 November 2015, the number of species totals 1188, comprising 16 orders, 61 families and 199 genera. The checklist includes nine orders, 34 families, 105 genera and 509 species of sharks; six orders, 24 families, 88 genera and 630 species of batoids (skates and rays); one order, three families, six genera and 49 species of holocephalans (chimaeras). The most speciose shark orders are the Carcharhiniformes with 284 species, followed by the Squaliformes with 119. The most species-rich batoid orders are the Rajiformes with 285 species and the Myliobatiformes with 210. This checklist represents the first global checklist of chondrichthyans to include information on maximum size, geographic and depth distributions, as well as comments on taxonomically problematic species and recent and regularly overlooked synonymizations. Furthermore, a detailed analysis of the biogeographical diversity of the species across 10 major areas of occurrence is given, including updated figures for previously published hotspots of chondrichthyan biodiversity, providing the detailed numbers of chondrichthyan species per major area, and revealing centres of distribution for several taxa.",
    url = "https://doi.org/10.1111/jfb.12874",
    doi = "10.1111/jfb.12874",
    openalex = "W2254068788",
    references = "doi101038164766a0, doi10103835002501, doi101093bioscience1610752a, doi101111j14610248201001489x, doi101126science1067728, doi1011646zootaxa375213, doi1011646zootaxa375215, doi1011646zootaxa388211, doi101643ot04142, doi1023071446735, doi1023071447424, doi106024jmbai201456101750s17, doi107554elife00590, openalexw1511461941, openalexw2883478268, openalexw2900647185, openalexw571605905"
}

Abstract A new lonchidiid genus, Pristrisodus, from the Upper Triassic Tiki Formation of India is described based on multiple, well-preserved, isolated teeth. Comparative analysis resulted in synonymizing Parvodus tikiensis and Lissodus duffini, which are known from the same horizon and resulted in a new taxon, Pristrisodus tikiensis n. comb. These teeth are elongated with mesiodistal length greater than or equal to twice the labiolingual width and have a high principal cusp, lateral cusplets, a distinct ridge near the crown-root junction labially and higher up on the crown lingually, weak ornamentation, and linear depression along the crown-root junction. Five morphotypes based on overall shape, robustness and crown height are determined. The teeth show a gradual monognathic heterodonty. The anterolateral teeth (morphotypes I−II) have high, pyramidal principal cusp with two or three small but pointed cusplets, and triangular labial and lingual protuberance. The posterolateral teeth (morphotypes III−IV) have four incipient cusplets, relatively low principal cusp, bilobed/rounded, hanging labial and incipient lingual protuberances. Morphotype V comprises anterior teeth that are broad, triangular and robust, and have rounded/blunt principal cusp, one cusplet, and low, hanging labial peg. Multivariate analyses corroborate the qualitative assessment of the Indian hybodonts. Dental histology of Pristrisodus n. gen., shows that it is distinctly different from other lonchidiid genera. The assemblage of freshwater sharks, along with other vertebrate microfossils of the Tiki Formation, shows similarity with that of the lower Tecovas Formation of the Chinle Group, USA. The euryhaline nature resulted in the adaptation of the hybodonts to freshwater systems in India during the Carnian.

@article{doi101017jpa201763,
    author = "Bhat, Mohd Shafi and Ray, Sanghamitra and Datta, P. M.",
    title = "A new hybodont shark (Chondrichthyes, Elasmobranchii) from the Upper Triassic Tiki Formation of India with remarks on its dental histology and biostratigraphy",
    year = "2017",
    journal = "Journal of Paleontology",
    abstract = "Abstract A new lonchidiid genus, Pristrisodus, from the Upper Triassic Tiki Formation of India is described based on multiple, well-preserved, isolated teeth. Comparative analysis resulted in synonymizing Parvodus tikiensis and Lissodus duffini, which are known from the same horizon and resulted in a new taxon, Pristrisodus tikiensis n. comb. These teeth are elongated with mesiodistal length greater than or equal to twice the labiolingual width and have a high principal cusp, lateral cusplets, a distinct ridge near the crown-root junction labially and higher up on the crown lingually, weak ornamentation, and linear depression along the crown-root junction. Five morphotypes based on overall shape, robustness and crown height are determined. The teeth show a gradual monognathic heterodonty. The anterolateral teeth (morphotypes I−II) have high, pyramidal principal cusp with two or three small but pointed cusplets, and triangular labial and lingual protuberance. The posterolateral teeth (morphotypes III−IV) have four incipient cusplets, relatively low principal cusp, bilobed/rounded, hanging labial and incipient lingual protuberances. Morphotype V comprises anterior teeth that are broad, triangular and robust, and have rounded/blunt principal cusp, one cusplet, and low, hanging labial peg. Multivariate analyses corroborate the qualitative assessment of the Indian hybodonts. Dental histology of Pristrisodus n. gen., shows that it is distinctly different from other lonchidiid genera. The assemblage of freshwater sharks, along with other vertebrate microfossils of the Tiki Formation, shows similarity with that of the lower Tecovas Formation of the Chinle Group, USA. The euryhaline nature resulted in the adaptation of the hybodonts to freshwater systems in India during the Carnian.",
    url = "https://doi.org/10.1017/jpa.2017.63",
    doi = "10.1017/jpa.2017.63",
    openalex = "W2763745796",
    references = "doi101002jmor1073, doi104202app000562013, doi105962p150189, openalexw1252084533, openalexw641496887"
}

The cranial diversity of sharks reflects disparate biomechanical adaptations to feeding. In order to be able to investigate and better understand the ecomorphology of extant shark feeding systems, we created a x-ray computed tomography (CT) library of shark cranial anatomy with three-dimensional (3D) lower jaw reconstructions. This is used to examine and quantify lower jaw disparity in extant shark species in a separate study. The library is divided in a dataset comprised of medical CT scans of 122 sharks (Selachimorpha, Chondrichthyes) representing 73 extant species, including digitized morphology of entire shark specimens. This CT dataset and additional data provided by other researchers was used to reconstruct a second dataset containing 3D models of the left lower jaw for 153 individuals representing 94 extant shark species. These datasets form an extensive anatomical record of shark skeletal anatomy, necessary for comparative morphological, biomechanical, ecological and phylogenetic studies.

@article{doi101038sdata201747,
    author = "Kamminga, Pepijn and Bruin, Paul W. De and Geleijns, Jacob and Brazeau, Martin",
    title = "X-ray computed tomography library of shark anatomy and lower jaw surface models",
    year = "2017",
    journal = "Scientific Data",
    abstract = "The cranial diversity of sharks reflects disparate biomechanical adaptations to feeding. In order to be able to investigate and better understand the ecomorphology of extant shark feeding systems, we created a x-ray computed tomography (CT) library of shark cranial anatomy with three-dimensional (3D) lower jaw reconstructions. This is used to examine and quantify lower jaw disparity in extant shark species in a separate study. The library is divided in a dataset comprised of medical CT scans of 122 sharks (Selachimorpha, Chondrichthyes) representing 73 extant species, including digitized morphology of entire shark specimens. This CT dataset and additional data provided by other researchers was used to reconstruct a second dataset containing 3D models of the left lower jaw for 153 individuals representing 94 extant shark species. These datasets form an extensive anatomical record of shark skeletal anatomy, necessary for comparative morphological, biomechanical, ecological and phylogenetic studies.",
    url = "https://doi.org/10.1038/sdata.2017.47",
    doi = "10.1038/sdata.2017.47",
    openalex = "W2605533774",
    references = "doi101002jmor10342"
}

BACKGROUND: The origin of jawed vertebrates was marked by profound reconfigurations of the skeleton and muscles of the head and by the acquisition of two sets of paired appendages. Extant cartilaginous fish retained numerous plesiomorphic characters of jawed vertebrates, which include several aspects of their musculature. Therefore, myogenic studies on sharks are essential in yielding clues on the developmental processes involved in the origin of the muscular anatomy. RESULTS:. CONCLUSION:, reinforcing the idea that head tissues have contributed to the formation of the pectoral appendages in the common ancestor of extant gnathostomes. In addition, temporal differences in the formation of some cranial muscles between chondrichthyans and osteichthyans might support the hypothesis that the similarity between the musculature of the mandibular arch and of the other pharyngeal arches represents a derived feature of jawed vertebrates.

@article{doi101186s129830170216y,
    author = "Ziermann, Janine M. and Freitas, Renata and Diogo, Rui",
    title = "Muscle development in the shark Scyliorhinus canicula: implications for the evolution of the gnathostome head and paired appendage musculature",
    year = "2017",
    journal = "Frontiers in Zoology",
    abstract = "BACKGROUND: The origin of jawed vertebrates was marked by profound reconfigurations of the skeleton and muscles of the head and by the acquisition of two sets of paired appendages. Extant cartilaginous fish retained numerous plesiomorphic characters of jawed vertebrates, which include several aspects of their musculature. Therefore, myogenic studies on sharks are essential in yielding clues on the developmental processes involved in the origin of the muscular anatomy. RESULTS:. CONCLUSION:, reinforcing the idea that head tissues have contributed to the formation of the pectoral appendages in the common ancestor of extant gnathostomes. In addition, temporal differences in the formation of some cranial muscles between chondrichthyans and osteichthyans might support the hypothesis that the similarity between the musculature of the mandibular arch and of the other pharyngeal arches represents a derived feature of jawed vertebrates.",
    url = "https://doi.org/10.1186/s12983-017-0216-y",
    doi = "10.1186/s12983-017-0216-y",
    openalex = "W2697450371",
    references = "doi101111zoj12186"
}

The lower Miocene Pirabas Formation in the North of Brazil was deposited under influence of the proto-Amazon River and is characterized by large changes in the ecological niches from the early Miocene onwards. To evaluate these ecological changes, the elasmobranch fauna of the fully marine, carbonate-rich beds was investigated. A diverse fauna with 24 taxa of sharks and rays was identified with the dominant groups being carcharhiniforms and myliobatiforms. This faunal composition is similar to other early Miocene assemblages from the proto-Carribbean bioprovince. However, the Pirabas Formation has unique features compared to the other localities; being the only Neogene fossil fish assemblage described from the Atlantic coast of Tropical Americas. Phosphate oxygen isotope composition of elasmobranch teeth served as proxies for paleotemperatures and paleoecology. The data are compatible with a predominantly tropical marine setting with recognized inshore and offshore habitats with some probable depth preferences (e.g., Aetomylaeus groups). Paleohabitat of taxa particularly found in the Neogene of the Americas (†Carcharhinus ackermannii, †Aetomylaeus cubensis) are estimated to have been principally coastal and shallow waters. Larger variation among the few analyzed modern selachians reflects a larger range for the isotopic composition of recent seawater compared to the early Miocene. This probably links to an increased influence of the Amazon River in the coastal regions during the Holocene.

@article{doi101371journalpone0182740,
    author = "Aguilera, Orangel and Luz, Zoneibe and Carrillo-Briceño, Jorge D. and Kocsis, László and Vennemann, Torsten and de Toledo, Peter Mann and Nogueira, Afonso César Rodrigues and Amorim, Kamilla Borges and Moraes-Santos, Heloı́sa Maria and dos Reis Polck, Márcia Aparecida and de Lourdes Pinheiro Ruivo, Maria and Linhares, Ana Paula and Monteiro‐Neto, Cassiano",
    title = "Neogene sharks and rays from the Brazilian ‘Blue Amazon’",
    year = "2017",
    journal = "PLoS ONE",
    abstract = "The lower Miocene Pirabas Formation in the North of Brazil was deposited under influence of the proto-Amazon River and is characterized by large changes in the ecological niches from the early Miocene onwards. To evaluate these ecological changes, the elasmobranch fauna of the fully marine, carbonate-rich beds was investigated. A diverse fauna with 24 taxa of sharks and rays was identified with the dominant groups being carcharhiniforms and myliobatiforms. This faunal composition is similar to other early Miocene assemblages from the proto-Carribbean bioprovince. However, the Pirabas Formation has unique features compared to the other localities; being the only Neogene fossil fish assemblage described from the Atlantic coast of Tropical Americas. Phosphate oxygen isotope composition of elasmobranch teeth served as proxies for paleotemperatures and paleoecology. The data are compatible with a predominantly tropical marine setting with recognized inshore and offshore habitats with some probable depth preferences (e.g., Aetomylaeus groups). Paleohabitat of taxa particularly found in the Neogene of the Americas (†Carcharhinus ackermannii, †Aetomylaeus cubensis) are estimated to have been principally coastal and shallow waters. Larger variation among the few analyzed modern selachians reflects a larger range for the isotopic composition of recent seawater compared to the early Miocene. This probably links to an increased influence of the Amazon River in the coastal regions during the Holocene.",
    url = "https://doi.org/10.1371/journal.pone.0182740",
    doi = "10.1371/journal.pone.0182740",
    openalex = "W2745387615",
    references = "doi101007s106410140294z, doi10166612117"
}

@incollection{doi101016b9780128096338206031,
    author = "Awruch, Cynthia A.",
    title = "Chondrichthyes (Sharks, Rays, Skates and Chimaeras)",
    year = "2018",
    booktitle = "Elsevier eBooks",
    url = "https://doi.org/10.1016/b978-0-12-809633-8.20603-1",
    doi = "10.1016/b978-0-12-809633-8.20603-1",
    openalex = "W2790019054",
    references = "doi101007bf00004997, doi101016jygcen201305021, doi101016s1546509808602137, doi101093icb212473, doi101098rsbl20070189, doi101098rspb19970181, doi101111j14672979201100436x, doi1012019781439856000, doi101201b11867"
}

@article{doi101038s4155901704484,
    author = "Stein, R. William and Mull, Christopher G. and Kuhn, Tyler S. and Aschliman, Neil C. and Davidson, Lindsay N. K. and Joy, Jeffrey B. and Smith, Gordon J. and Dulvy, Nicholas K. and Mooers, Arne Ø.",
    title = "Global priorities for conserving the evolutionary history of sharks, rays and chimaeras",
    year = "2018",
    journal = "Nature Ecology \& Evolution",
    url = "https://doi.org/10.1038/s41559-017-0448-4",
    doi = "10.1038/s41559-017-0448-4",
    openalex = "W2783187939",
    references = "doi1010160006320792912013, doi101017cbo9780511528446003, doi101023a1018471324332, doi101038nature11631, doi101038nmeth2109, doi10108010635150390235520, doi101093bibbbn013, doi101093bioinformaticsbtl446, doi101093molbevmsq147, doi101093molbevmss075, doi101093nargkf436, doi101093nargki198, doi101098rspb19970181, doi101111jfb12874, doi1026879424"
}

Modern cartilaginous fishes are divided into elasmobranchs (sharks, rays and skates) and chimaeras, and the lack of established whole-genome sequences for the former has prevented our understanding of early vertebrate evolution and the unique phenotypes of elasmobranchs. Here we present de novo whole-genome assemblies of brownbanded bamboo shark and cloudy catshark and an improved assembly of the whale shark genome. These relatively large genomes (3.8-6.7 Gbp) contain sparse distributions of coding genes and regulatory elements and exhibit reduced molecular evolutionary rates. Our thorough genome annotation revealed Hox C genes previously hypothesized to have been lost, as well as distinct gene repertories of opsins and olfactory receptors that would be associated with adaptation to unique underwater niches. We also show the early establishment of the genetic machinery governing mammalian homoeostasis and reproduction at the jawed vertebrate ancestor. This study, supported by genomic, transcriptomic and epigenomic resources, provides a foundation for the comprehensive, molecular exploration of phenotypes unique to sharks and insights into the evolutionary origins of vertebrates.

@article{doi101038s4155901806735,
    author = "Hara, Yuichiro and Yamaguchi, Kazuaki and Onimaru, Koh and Kadota, Mitsutaka and Koyanagi, Mitsumasa and Keeley, Sean D. and Tatsumi, Kaori and Tanaka, Kaori and Motone, Fumio and Kageyama, Yuka and Nozu, Ryo and Adachi, Noritaka and Nishimura, Osamu and Nakagawa, Reiko and Tanegashima, Chiharu and Kiyatake, Itsuki and Matsumoto, Rui and Murakumo, Kiyomi and Nishida, Kiyonori and Terakita, Akihisa and Kuratani, Shigeru and Sato, Keiichi and Hyodo, Susumu and Kuraku, Shigehiro",
    title = "Shark genomes provide insights into elasmobranch evolution and the origin of vertebrates",
    year = "2018",
    journal = "Nature Ecology \& Evolution",
    abstract = "Modern cartilaginous fishes are divided into elasmobranchs (sharks, rays and skates) and chimaeras, and the lack of established whole-genome sequences for the former has prevented our understanding of early vertebrate evolution and the unique phenotypes of elasmobranchs. Here we present de novo whole-genome assemblies of brownbanded bamboo shark and cloudy catshark and an improved assembly of the whale shark genome. These relatively large genomes (3.8-6.7 Gbp) contain sparse distributions of coding genes and regulatory elements and exhibit reduced molecular evolutionary rates. Our thorough genome annotation revealed Hox C genes previously hypothesized to have been lost, as well as distinct gene repertories of opsins and olfactory receptors that would be associated with adaptation to unique underwater niches. We also show the early establishment of the genetic machinery governing mammalian homoeostasis and reproduction at the jawed vertebrate ancestor. This study, supported by genomic, transcriptomic and epigenomic resources, provides a foundation for the comprehensive, molecular exploration of phenotypes unique to sharks and insights into the evolutionary origins of vertebrates.",
    url = "https://doi.org/10.1038/s41559-018-0673-5",
    doi = "10.1038/s41559-018-0673-5",
    openalex = "W2894335751",
    references = "doi101002jez1402670309, doi101038s4155901704484"
}

Here, we report trading of endangered shark species in a world hotspot for elasmobranch conservation in Brazil. Data on shark fisheries are scarce in Brazil, although the northern and northeastern regions have the highest indices of shark bycatch. Harvest is made primarily with processed carcasses lacking head and fins, which hampers reliable species identification and law enforcement on illegal catches. We used partial sequences of two mitochondrial genes (COI and/or NADH2) to identify 17 shark species from 427 samples being harvested and marketed on the northern coast of Brazil. Nine species (53%) are listed under some extinction threat category according to Brazilian law and international authorities (IUCN - International Union for Conservation of Nature; CITES - Convention on International Trade of Endangered Species of Wild Fauna and Flora). The number increases to 13 (76%) if we also consider the Near Threatened category. Hammerhead sharks are under threat worldwide, and composed 18.7% of samples, with Sphyrna mokarran being the fourth most common species among samples. As illegal trade of threatened shark species is a worldwide conservation problem, molecular identification of processed meat or specimens lacking diagnostic body parts is a highly effective tool for species identification and law enforcement.

@article{doi101038s41598018216835,
    author = "Feitosa, Leonardo Manir and Martins, Ana Paula Barbosa and Giarrizzo, Tommaso and Macedo, Wagner and Monteiro, Iann Leonardo Pinheiro and Gemaque, Romário and Nunes, Jorge Luíz Silva and Gomes, Fernanda P. and Schneider, Horácio and Sampaio, Iracilda and Souza, Rosália Furtado Cutrim and de Luna Sales, João Bráullio and da Silva Rodrigues‐Filho, Luis Fernando and Tchaicka, Lígia and Carvalho-Costa, Luís Fernando",
    title = "DNA-based identification reveals illegal trade of threatened shark species in a global elasmobranch conservation hotspot",
    year = "2018",
    journal = "Scientific Reports",
    abstract = "Here, we report trading of endangered shark species in a world hotspot for elasmobranch conservation in Brazil. Data on shark fisheries are scarce in Brazil, although the northern and northeastern regions have the highest indices of shark bycatch. Harvest is made primarily with processed carcasses lacking head and fins, which hampers reliable species identification and law enforcement on illegal catches. We used partial sequences of two mitochondrial genes (COI and/or NADH2) to identify 17 shark species from 427 samples being harvested and marketed on the northern coast of Brazil. Nine species (53\%) are listed under some extinction threat category according to Brazilian law and international authorities (IUCN - International Union for Conservation of Nature; CITES - Convention on International Trade of Endangered Species of Wild Fauna and Flora). The number increases to 13 (76\%) if we also consider the Near Threatened category. Hammerhead sharks are under threat worldwide, and composed 18.7\% of samples, with Sphyrna mokarran being the fourth most common species among samples. As illegal trade of threatened shark species is a worldwide conservation problem, molecular identification of processed meat or specimens lacking diagnostic body parts is a highly effective tool for species identification and law enforcement.",
    url = "https://doi.org/10.1038/s41598-018-21683-5",
    doi = "10.1038/s41598-018-21683-5",
    openalex = "W2788150542",
    references = "doi101111j10958649201203265x, doi101111jfb12874"
}

A general northward shift in marine species distributions has been observed in the western North Atlantic Ocean, which may have significant ecological consequences. Large coastal sharks can have wide migratory distributions but show fidelity to specific nursery habitats. Here we show evidence for nursery range expansion into Pamlico Sound, North Carolina by a marine apex predator, the Bull Shark (Carcharhinus leucas). Previous assessments have shown little to no use of estuarine North Carolina waters as nursery habitat by Bull Sharks from 1965-2011. Juvenile sharks were rarely captured in a fishery-independent gillnet survey conducted by the North Carolina Division of Marine Fisheries (NCDMF) from 2003-2011, but were present every year from 2011-2016. Juvenile Bull Shark presence in the Sound was strongly related to early summer temperatures and late summer salinities, which have increased in the estuary over the 13 survey years, and further evidence for increasing water temperatures in Pamlico Sound was found in a 45-year data set for the NCDMF estuarine trawl survey. These results suggest that increasing water temperature and salinity have allowed Bull Sharks to expand their nursery habitat. This shift will have unknown, but potentially strong, impacts on both the local ecosystem and interactions with humans.

@article{doi101038s4159801824510z,
    author = "Bangley, Charles W. and Paramore, Lee M. and Shiffman, David S. and Rulifson, Roger A.",
    title = "Increased Abundance and Nursery Habitat Use of the Bull Shark (Carcharhinus leucas) in Response to a Changing Environment in a Warm-Temperate Estuary",
    year = "2018",
    journal = "Scientific Reports",
    abstract = "A general northward shift in marine species distributions has been observed in the western North Atlantic Ocean, which may have significant ecological consequences. Large coastal sharks can have wide migratory distributions but show fidelity to specific nursery habitats. Here we show evidence for nursery range expansion into Pamlico Sound, North Carolina by a marine apex predator, the Bull Shark (Carcharhinus leucas). Previous assessments have shown little to no use of estuarine North Carolina waters as nursery habitat by Bull Sharks from 1965-2011. Juvenile sharks were rarely captured in a fishery-independent gillnet survey conducted by the North Carolina Division of Marine Fisheries (NCDMF) from 2003-2011, but were present every year from 2011-2016. Juvenile Bull Shark presence in the Sound was strongly related to early summer temperatures and late summer salinities, which have increased in the estuary over the 13 survey years, and further evidence for increasing water temperatures in Pamlico Sound was found in a 45-year data set for the NCDMF estuarine trawl survey. These results suggest that increasing water temperature and salinity have allowed Bull Sharks to expand their nursery habitat. This shift will have unknown, but potentially strong, impacts on both the local ecosystem and interactions with humans.",
    url = "https://doi.org/10.1038/s41598-018-24510-z",
    doi = "10.1038/s41598-018-24510-z",
    openalex = "W2797871109",
    references = "doi101007s1116001493648, doi101080000284872011618352"
}

Abstract The extinction risk of sharks, rays and chimaeras is higher than that for most other vertebrates due to low intrinsic population growth rates of many species and the fishing intensity they face. The Arabian Sea and adjacent waters border some of the most important chondrichthyan fishing and trading nations globally, yet there has been no previous attempt to assess the conservation status of species occurring here. Using IUCN Red List of Threatened Species Categories and Criteria and their guidelines for application at the regional level, we present the first assessment of extinction risk for 153 species of sharks, rays and chimaeras. Results indicate that this region, home to 15% of described chondrichthyans including 30 endemic species, has some of the most threatened chondrichthyan populations in the world. Seventy‐eight species (50.9%) were assessed as threatened (Critically Endangered, Endangered or Vulnerable), and 27 species (17.6%) as Near Threatened. Twenty‐nine species (19%) were Data Deficient with insufficient information to assess their status. Chondrichthyan populations have significantly declined due to largely uncontrolled and unregulated fisheries combined with habitat degradation. Further, there is limited political will and national and regional capacities to assess, manage, conserve or rebuild stocks. Outside the few deepsea locations that are lightly exploited, the prognosis for the recovery of most species is poor in the near‐absence of management. Concerted national and regional management measures are urgently needed to ensure extinctions are avoided, the sustainability of more productive species is secured, and to avoid the continued thinning of the regional food security portfolio.

@article{doi101111faf12311,
    author = "Jabado, Rima W. and Kyne, Peter M. and Pollom, Riley A. and Ebert, David A. and Simpfendorfer, Colin A. and Ralph, Gina M. and Dhaheri, Shaikha Salem Al and Akhilesh, K and Ali, Khadeeja and Ali, Mohamud Hassan and Mamari, Tariq M. S. Al and Bineesh, K. K. and Hassan, Igbal S. El and Fernando, Daniel and Grandcourt, Edwin and Khan, Muhammad Moazzam and Moore, Alec B. M. and Owfi, Fereidoon and Robinson, David P. and Romanov, Evgeny V. and Soares, Ana‐Lucia and Spaet, Julia L. Y. and Tesfamichael, Dawit and Valinassab, Tooraj and Dulvy, Nicholas K.",
    title = "Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters",
    year = "2018",
    journal = "Fish and Fisheries",
    abstract = "Abstract The extinction risk of sharks, rays and chimaeras is higher than that for most other vertebrates due to low intrinsic population growth rates of many species and the fishing intensity they face. The Arabian Sea and adjacent waters border some of the most important chondrichthyan fishing and trading nations globally, yet there has been no previous attempt to assess the conservation status of species occurring here. Using IUCN Red List of Threatened Species Categories and Criteria and their guidelines for application at the regional level, we present the first assessment of extinction risk for 153 species of sharks, rays and chimaeras. Results indicate that this region, home to 15\% of described chondrichthyans including 30 endemic species, has some of the most threatened chondrichthyan populations in the world. Seventy‐eight species (50.9\%) were assessed as threatened (Critically Endangered, Endangered or Vulnerable), and 27 species (17.6\%) as Near Threatened. Twenty‐nine species (19\%) were Data Deficient with insufficient information to assess their status. Chondrichthyan populations have significantly declined due to largely uncontrolled and unregulated fisheries combined with habitat degradation. Further, there is limited political will and national and regional capacities to assess, manage, conserve or rebuild stocks. Outside the few deepsea locations that are lightly exploited, the prognosis for the recovery of most species is poor in the near‐absence of management. Concerted national and regional management measures are urgently needed to ensure extinctions are avoided, the sustainability of more productive species is secured, and to avoid the continued thinning of the regional food security portfolio.",
    url = "https://doi.org/10.1111/faf.12311",
    doi = "10.1111/faf.12311",
    openalex = "W2885773139",
    references = "doi101017s0376892909990191"
}

The aim of this 14 year study was to elucidate the entire courtship and mating behaviour of manta rays Mobula alfredi and M. birostris using behavioural observations, video and photographic records. From 2003 to 2016, over 11,000 surveys were undertaken at known manta ray aggregation sites in the Maldives to record any observed manta rays reproductive activity. From 47,591 photo-ID sightings, 4,247 individual M. alfredi were identified and 226 individual M. birostris from 229 photo-ID sightings, all recorded at 22 atolls across 265 different sites. Courtship activity was observed on 206 surveys at 30 different sites. A total of 229 courtship events were recorded, with 90% (n = 205) of them occurring at cleaning sites. The observed courtship activity was categorised into seven distinct stages which are described in detail: initiation, endurance, evasion, pre-copulatory positioning, copulation, post-copulatory holding and separation. Photographs provide the first scientific record of the entirety of manta rays courtship and mating. Both M. alfredi and M. birostris appear to engage in the same elaborate courtship rituals, exhibiting the same behaviours during all stages of the courtship and mating process.

@article{doi101111jfb13768,
    author = "Stevens, Guy M. W. and Hawkins, Julie P. and Roberts, Callum M.",
    title = "Courtship and mating behaviour of manta rays Mobula alfredi and M. birostris in the Maldives",
    year = "2018",
    journal = "Journal of Fish Biology",
    abstract = "The aim of this 14 year study was to elucidate the entire courtship and mating behaviour of manta rays Mobula alfredi and M. birostris using behavioural observations, video and photographic records. From 2003 to 2016, over 11,000 surveys were undertaken at known manta ray aggregation sites in the Maldives to record any observed manta rays reproductive activity. From 47,591 photo-ID sightings, 4,247 individual M. alfredi were identified and 226 individual M. birostris from 229 photo-ID sightings, all recorded at 22 atolls across 265 different sites. Courtship activity was observed on 206 surveys at 30 different sites. A total of 229 courtship events were recorded, with 90\% (n = 205) of them occurring at cleaning sites. The observed courtship activity was categorised into seven distinct stages which are described in detail: initiation, endurance, evasion, pre-copulatory positioning, copulation, post-copulatory holding and separation. Photographs provide the first scientific record of the entirety of manta rays courtship and mating. Both M. alfredi and M. birostris appear to engage in the same elaborate courtship rituals, exhibiting the same behaviours during all stages of the courtship and mating process.",
    url = "https://doi.org/10.1111/jfb.13768",
    doi = "10.1111/jfb.13768",
    openalex = "W2887347070",
    references = "doi1012019781439856000"
}

The dalatiid genus Isistius Gill (1864) has three valid species currently recognized in the literature: Isistius brasiliensis Quoy & Gaimard (1824), I. plutodus Garrick & Springer (1964), and I. labialis Meng, Zhu & Li (1985). The most common species, I. brasiliensis, has a wide geographic distribution and is found in subtemperate and tropical seas circumglobally. A comparative analysis of specimens from different localities throughout its range, however, had never been undertaken. In the present paper, the morphological variation of this species along its entire distribution has been thoroughly analyzed, corroborating that it represents a single widespread species and that I. labialis is its junior synonym. The other congeneric species, I. plutodus, is known from only a few specimens and is also distributed worldwide. A detailed comparative analysis of available material of I. plutodus was conducted verifying its validity as a single widespread species. The present study analyzed in detail the external morphology (coloration, dentition, dermal denticles), internal morphology (skeleton, musculature), lateral-line canals, and morphometric and meristic characters of species of Isistius in order to better define the genus and its included valid species.

@article{doi101371journalpone0201913,
    author = "Petean, Flávia F. and de Carvalho, Marcelo R.",
    title = "Comparative morphology and systematics of the cookiecutter sharks, genus Isistius Gill (1864) (Chondrichthyes: Squaliformes: Dalatiidae)",
    year = "2018",
    journal = "PLoS ONE",
    abstract = "The dalatiid genus Isistius Gill (1864) has three valid species currently recognized in the literature: Isistius brasiliensis Quoy \& Gaimard (1824), I. plutodus Garrick \& Springer (1964), and I. labialis Meng, Zhu \& Li (1985). The most common species, I. brasiliensis, has a wide geographic distribution and is found in subtemperate and tropical seas circumglobally. A comparative analysis of specimens from different localities throughout its range, however, had never been undertaken. In the present paper, the morphological variation of this species along its entire distribution has been thoroughly analyzed, corroborating that it represents a single widespread species and that I. labialis is its junior synonym. The other congeneric species, I. plutodus, is known from only a few specimens and is also distributed worldwide. A detailed comparative analysis of available material of I. plutodus was conducted verifying its validity as a single widespread species. The present study analyzed in detail the external morphology (coloration, dentition, dermal denticles), internal morphology (skeleton, musculature), lateral-line canals, and morphometric and meristic characters of species of Isistius in order to better define the genus and its included valid species.",
    url = "https://doi.org/10.1371/journal.pone.0201913",
    doi = "10.1371/journal.pone.0201913",
    openalex = "W2888574467",
    references = "doi101038srep04328, doi1011646zootaxa375213"
}

Elasmobranchs, the group of cartilaginous fishes that include sharks and rays, are especially vulnerable to overfishing due to low fecundity and late sexual maturation. A significant number of elasmobranch species are currently overexploited or threatened by fisheries activities. Additionally, several recent reports have indicated that there has been a reduction in regional elasmobranch population sizes. Brazil is an important player in elasmobranch fisheries and one of the largest importers of shark meat. However, carcasses entering the shark meat market have usually had their fins and head removed, which poses a challenge to reliable species identification based on the morphology of captured individuals. This is further complicated by the fact that the internal Brazilian market trades several different elasmobranch species under a common popular name: "cação." The use of such imprecise nomenclature, even among governmental agencies, is problematic for both controlling the negative effects of shark consumption and informing the consumer about the origins of the product. In this study, we used DNA barcoding (mtDNA, COI gene) to identify, at the species level, "cação" samples available in local markets from Southern Brazil. We collected 63 samples traded as "cação," which we found to correspond to 20 different species. These included two teleost species: Xiphias gladius (n = 1) and Genidens barbus (n = 6), and 18 species from seven elasmobranch orders (Carcharhiniformes, n = 42; Squaliformes, n = 3; Squatiniformes, n = 2; Rhinopristiformes, n = 4; Myliobatiformes, n = 3; Rajiformes, n = 1; and Torpediniformes, n = 1). The most common species in our sample were Prionace glauca (n = 15) and Sphyrna lewini (n = 14), while all other species were represented by four samples or less. Considering IUCN criteria, 47% of the elasmobranch species found are threatened at the global level, while 53% are threatened and 47% are critically endangered in Brazil. These results underline that labeling the meat of any shark species as "cação" is problematic for monitoring catch allocations from the fishing industry and discourages consumer engagement in conservationist practices through informed decision-making.

@article{doi103389fgene201800138,
    author = "Almerón-Souza, Fernanda and Sperb, Christian and de Castilho, Carolina Leal and Figueiredo, Pedro Ivo C. C. and Gonçalves, Leonardo Tresoldi and Machado, Rodrigo and de Oliveira, Larissa Rosa and Valiati, Victor Hugo and Fagundes, Nelson J. R.",
    title = "Molecular Identification of Shark Meat From Local Markets in Southern Brazil Based on DNA Barcoding: Evidence for Mislabeling and Trade of Endangered Species",
    year = "2018",
    journal = "Frontiers in Genetics",
    abstract = {Elasmobranchs, the group of cartilaginous fishes that include sharks and rays, are especially vulnerable to overfishing due to low fecundity and late sexual maturation. A significant number of elasmobranch species are currently overexploited or threatened by fisheries activities. Additionally, several recent reports have indicated that there has been a reduction in regional elasmobranch population sizes. Brazil is an important player in elasmobranch fisheries and one of the largest importers of shark meat. However, carcasses entering the shark meat market have usually had their fins and head removed, which poses a challenge to reliable species identification based on the morphology of captured individuals. This is further complicated by the fact that the internal Brazilian market trades several different elasmobranch species under a common popular name: "cação." The use of such imprecise nomenclature, even among governmental agencies, is problematic for both controlling the negative effects of shark consumption and informing the consumer about the origins of the product. In this study, we used DNA barcoding (mtDNA, COI gene) to identify, at the species level, "cação" samples available in local markets from Southern Brazil. We collected 63 samples traded as "cação," which we found to correspond to 20 different species. These included two teleost species: Xiphias gladius (n = 1) and Genidens barbus (n = 6), and 18 species from seven elasmobranch orders (Carcharhiniformes, n = 42; Squaliformes, n = 3; Squatiniformes, n = 2; Rhinopristiformes, n = 4; Myliobatiformes, n = 3; Rajiformes, n = 1; and Torpediniformes, n = 1). The most common species in our sample were Prionace glauca (n = 15) and Sphyrna lewini (n = 14), while all other species were represented by four samples or less. Considering IUCN criteria, 47\% of the elasmobranch species found are threatened at the global level, while 53\% are threatened and 47\% are critically endangered in Brazil. These results underline that labeling the meat of any shark species as "cação" is problematic for monitoring catch allocations from the fishing industry and discourages consumer engagement in conservationist practices through informed decision-making.},
    url = "https://doi.org/10.3389/fgene.2018.00138",
    doi = "10.3389/fgene.2018.00138",
    openalex = "W2802617351",
    references = "doi101111j10958649201203265x"
}

Understanding heterogeneity in species richness between closely related clades is a key research question in ecology and evolutionary biology. Multiple hypotheses have been proposed to interpret such diversity contrasts across the tree of life, with most studies focusing on speciation rates to explain clades' evolutionary radiations, while often neglecting extinction rates. Here we study a notorious biological model as exemplified by the sister relationships between mackerel sharks (Lamniformes, 15 extant species) and ground sharks (Carcharhiniformes, ∼290 extant species). Using a comprehensive fossil dataset, we found that the diversity dynamics of lamniforms waxed and waned following repeated cycles of radiation phases and declining phases. Radiation phases peaked up to 3 times the current diversity in the early Late Cretaceous. In the last 20 million years, the group declined to its present-day diversity. Along with a higher extinction risk for young species, we further show that this declining pattern is likely attributed to a combination of abiotic and biotic factors, with a cooling-driven extinction (negative correlation between temperature and extinction) and clade competition with some ground sharks. Competition from multiple clades successively drove the demise and replacement of mackerel sharks due to a failure to originate facing the rise of ground sharks, particularly since the Eocene. These effects came from ecologically similar carcharhiniform species inhibiting diversification of medium- and large-sized lamniforms. These results imply that the interplay between abiotic and biotic drivers had a substantial role in extinction and speciation, respectively, which determines the sequential rise and decline of marine apex predators.

@article{doi101073pnas1902693116,
    author = "Condamine, Fabien L. and Romieu, Jules and Guinot, Guillaume",
    title = "Climate cooling and clade competition likely drove the decline of lamniform sharks",
    year = "2019",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Understanding heterogeneity in species richness between closely related clades is a key research question in ecology and evolutionary biology. Multiple hypotheses have been proposed to interpret such diversity contrasts across the tree of life, with most studies focusing on speciation rates to explain clades' evolutionary radiations, while often neglecting extinction rates. Here we study a notorious biological model as exemplified by the sister relationships between mackerel sharks (Lamniformes, 15 extant species) and ground sharks (Carcharhiniformes, ∼290 extant species). Using a comprehensive fossil dataset, we found that the diversity dynamics of lamniforms waxed and waned following repeated cycles of radiation phases and declining phases. Radiation phases peaked up to 3 times the current diversity in the early Late Cretaceous. In the last 20 million years, the group declined to its present-day diversity. Along with a higher extinction risk for young species, we further show that this declining pattern is likely attributed to a combination of abiotic and biotic factors, with a cooling-driven extinction (negative correlation between temperature and extinction) and clade competition with some ground sharks. Competition from multiple clades successively drove the demise and replacement of mackerel sharks due to a failure to originate facing the rise of ground sharks, particularly since the Eocene. These effects came from ecologically similar carcharhiniform species inhibiting diversification of medium- and large-sized lamniforms. These results imply that the interplay between abiotic and biotic drivers had a substantial role in extinction and speciation, respectively, which determines the sequential rise and decline of marine apex predators.",
    url = "https://doi.org/10.1073/pnas.1902693116",
    doi = "10.1073/pnas.1902693116",
    openalex = "W2976793806",
    references = "doi101016jearscirev200712003, doi101017s1464793104006517, doi101038nature06588, doi101038ncomms2958, doi101073pnas0603587103, doi101111brv12203, doi101126science1061967, doi101126science1116412, doi101126science1157719, doi101198016214502760047131, doi101371journalpone0185185, doi105860choice344488"
}

Abstract Robust assessments of the effects of fishing require accounting for components of fishing mortality, including post‐release fishing mortality (F r). Random‐effects meta‐analysis synthesized F r in seven pelagic shark species captured, tagged and released with 401 pop‐up satellite archival tags compiled from 33 studies and three gears (longline, purse‐seine, rod & reel). The majority of F r outcomes occurred within days of release, and the summary effect size for F r was 0.27 [95% CI: 0.19–0.36], ranging from a low pooled effect size of 0.17 for blue shark (Prionace glauca, Carcharhinidae) to 0.38 (silky shark, Carcharhinus falciformis, Carcharhinidae). F r rates in blue shark were consistent over dissimilar spatial and temporal scales, and results from earlier meta‐analysis were replicated, which is the most powerful way to authenticate results. Condition at tagging was a strong predictor, and dichotomized survival outcomes in silky shark and no sex‐, size‐, location‐ or gear‐specific F r rates were demonstrated. Meta‐analyses and sensitivity analyses indicated exposure to risk factors and conditions whilst caught on the gear probably had the largest explanatory effect on F r, rather than stressors incurred during handling and release. Records from 549 tagged istiophorid billfishes (six species, three gears, 43 studies) demonstrated they are more robust to stressors sustained during capture, handling and release than pelagic sharks. Findings from previous meta‐analysis on F r rates in white marlin (Kajikia albida, Istiophoridae) were replicated. Synthesized F r rates enable prioritizing approaches to mitigate by‐catch fishing mortality, to improve the quality of stock and ecological risk assessments and to expand our knowledge of factors influencing trophic structure.

@article{doi101111faf12358,
    author = "Musyl, Michael K. and Gilman, Eric",
    title = "Meta‐analysis of post‐release fishing mortality in apex predatory pelagic sharks and white marlin",
    year = "2019",
    journal = "Fish and Fisheries",
    abstract = "Abstract Robust assessments of the effects of fishing require accounting for components of fishing mortality, including post‐release fishing mortality (F r). Random‐effects meta‐analysis synthesized F r in seven pelagic shark species captured, tagged and released with 401 pop‐up satellite archival tags compiled from 33 studies and three gears (longline, purse‐seine, rod \& reel). The majority of F r outcomes occurred within days of release, and the summary effect size for F r was 0.27 [95\% CI: 0.19–0.36], ranging from a low pooled effect size of 0.17 for blue shark (Prionace glauca, Carcharhinidae) to 0.38 (silky shark, Carcharhinus falciformis, Carcharhinidae). F r rates in blue shark were consistent over dissimilar spatial and temporal scales, and results from earlier meta‐analysis were replicated, which is the most powerful way to authenticate results. Condition at tagging was a strong predictor, and dichotomized survival outcomes in silky shark and no sex‐, size‐, location‐ or gear‐specific F r rates were demonstrated. Meta‐analyses and sensitivity analyses indicated exposure to risk factors and conditions whilst caught on the gear probably had the largest explanatory effect on F r, rather than stressors incurred during handling and release. Records from 549 tagged istiophorid billfishes (six species, three gears, 43 studies) demonstrated they are more robust to stressors sustained during capture, handling and release than pelagic sharks. Findings from previous meta‐analysis on F r rates in white marlin (Kajikia albida, Istiophoridae) were replicated. Synthesized F r rates enable prioritizing approaches to mitigate by‐catch fishing mortality, to improve the quality of stock and ecological risk assessments and to expand our knowledge of factors influencing trophic structure.",
    url = "https://doi.org/10.1111/faf.12358",
    doi = "10.1111/faf.12358",
    openalex = "W2920854021",
    references = "doi101111jfb12874"
}

Lamniformes (Chondrichthyes: Elasmobranchii) is a group of sharks that consists of 15 extant species with a wide range of morphological diversity. The most rarely captured lamniform is Odontaspis noronhai, and many aspects of its biology remain unknown to date. In this study, the skeletal anatomy of a previously described specimen of O. noronhai was examined using computed tomography. The new skeletal data were then added to a previously published morphology-based character matrix to conduct a new phylogenetic analysis of the Lamniformes. Our phylogenetic study strongly suggests non-monophyly of Odontaspididae, that traditionally consisted of Carcharias taurus, O. ferox, and O. noronhai. Thus, the family Carchariidae is formally resurrected for the genus Carcharias to separate it from the family Odontaspididae sensu stricto for Odontaspis. The overall topology of our phylogenetic trees is similar to that of previously published morphology-based trees and drastically different from the tree topology generally attained by molecular data that cluster Alopias, Megachasma, Odontaspis, and Pseudocarcharias together as a separate clade. The major topological discrepancy between molecular and morphological trees may be attributed to unconventionally asynchronous rates between morphological and molecular evolution, at least in certain species within the Lamniformes, along with likely manifestation of mosaic evolution. The recognition of the family Carchariidae is important to conservation biology, because the extinction of C. taurus would not only mean the elimination of the genus Carcharias, but also the entire family Carchariidae. Our study demonstrates the importance of the integration of both morphological and molecular information to understand organismal evolution.

@article{doi101643cg18160,
    author = "Stone, Nicholas R. and Shimada, Kenshu",
    title = "Skeletal Anatomy of the Bigeye Sand Tiger Shark, Odontaspis noronhai (Lamniformes: Odontaspididae), and Its Implications for Lamniform Phylogeny, Taxonomy, and Conservation Biology",
    year = "2019",
    journal = "Copeia",
    abstract = "Lamniformes (Chondrichthyes: Elasmobranchii) is a group of sharks that consists of 15 extant species with a wide range of morphological diversity. The most rarely captured lamniform is Odontaspis noronhai, and many aspects of its biology remain unknown to date. In this study, the skeletal anatomy of a previously described specimen of O. noronhai was examined using computed tomography. The new skeletal data were then added to a previously published morphology-based character matrix to conduct a new phylogenetic analysis of the Lamniformes. Our phylogenetic study strongly suggests non-monophyly of Odontaspididae, that traditionally consisted of Carcharias taurus, O. ferox, and O. noronhai. Thus, the family Carchariidae is formally resurrected for the genus Carcharias to separate it from the family Odontaspididae sensu stricto for Odontaspis. The overall topology of our phylogenetic trees is similar to that of previously published morphology-based trees and drastically different from the tree topology generally attained by molecular data that cluster Alopias, Megachasma, Odontaspis, and Pseudocarcharias together as a separate clade. The major topological discrepancy between molecular and morphological trees may be attributed to unconventionally asynchronous rates between morphological and molecular evolution, at least in certain species within the Lamniformes, along with likely manifestation of mosaic evolution. The recognition of the family Carchariidae is important to conservation biology, because the extinction of C. taurus would not only mean the elimination of the genus Carcharias, but also the entire family Carchariidae. Our study demonstrates the importance of the integration of both morphological and molecular information to understand organismal evolution.",
    url = "https://doi.org/10.1643/cg-18-160",
    doi = "10.1643/cg-18-160",
    openalex = "W2986461835",
    references = "doi101002jmor10342"
}

Long-lived species share life history traits such as slow growth, late maturity, and low fecundity, which lead to slow recovery rates and increase a population’s vulnerability to disturbance. The Greenland shark (Somniosus microcephalus) has recently been recognized as the world’s longest-lived vertebrate, but many questions regarding its biology, physiology, and ecology remain unanswered. Here we review how current and future research will fill knowledge gaps about the Greenland shark and provide an overall framework to guide research and management priorities for this species. Key advances include the potential for specialised ageing techniques and demographic studies to shed light on the distribution and age-class structure of Greenland shark populations. Advances in population genetics and genomics will reveal key factors contributing to the Greenland shark’s extreme longevity, range and population size, and susceptibility to environmental change. New tagging technologies and improvements in experimental and analytical design will allow detailed monitoring of movement behaviours and interactions among Greenland sharks and other marine species, while shedding light on habitat use and susceptibility to fisheries interactions. Interdisciplinary approaches, such as the combined use of stable isotope analysis and high-tech data-logging devices (i.e. accelerometers and acoustic hydrophones) have the potential to improve knowledge of feeding strategies, predatory capabilities, and the trophic role of Greenland sharks. Measures of physiology, including estimation of metabolic rate, as well as heart rate and function, will advance our understanding of the causes and consequences of long lifespans. Determining the extent and effects of current threats (as well as potential mitigation measures) will assist the development of policies, recommendations, and actions relevant for the management of this potentially vulnerable species. Through an interdisciplinary lens, we propose innovative approaches to direct the future study of Greenland sharks and promote the consideration of longevity as an important factor in research on aquatic and terrestrial predators.

@article{doi103389fmars201900087,
    author = "Edwards, Jena E. and Hiltz, Elizabeth and Broell, Franziska and Bushnell, Peter G. and Campana, Steven E. and Christiansen, Jørgen S. and Devine, Brynn M. and Gallant, Jeffrey J. and Hedges, Kevin J. and MacNeil, M. Aaron and McMeans, Bailey C. and Nielsen, Julius and Præbel, Kim and Skomal, Gregory B. and Steffensen, J. F. and Walter, Ryan P. and Watanabe, Yuuki and VanderZwaag, David and Hussey, Nigel E.",
    title = "Advancing Research for the Management of Long-Lived Species: A Case Study on the Greenland Shark",
    year = "2019",
    journal = "Frontiers in Marine Science",
    abstract = "Long-lived species share life history traits such as slow growth, late maturity, and low fecundity, which lead to slow recovery rates and increase a population’s vulnerability to disturbance. The Greenland shark (Somniosus microcephalus) has recently been recognized as the world’s longest-lived vertebrate, but many questions regarding its biology, physiology, and ecology remain unanswered. Here we review how current and future research will fill knowledge gaps about the Greenland shark and provide an overall framework to guide research and management priorities for this species. Key advances include the potential for specialised ageing techniques and demographic studies to shed light on the distribution and age-class structure of Greenland shark populations. Advances in population genetics and genomics will reveal key factors contributing to the Greenland shark’s extreme longevity, range and population size, and susceptibility to environmental change. New tagging technologies and improvements in experimental and analytical design will allow detailed monitoring of movement behaviours and interactions among Greenland sharks and other marine species, while shedding light on habitat use and susceptibility to fisheries interactions. Interdisciplinary approaches, such as the combined use of stable isotope analysis and high-tech data-logging devices (i.e. accelerometers and acoustic hydrophones) have the potential to improve knowledge of feeding strategies, predatory capabilities, and the trophic role of Greenland sharks. Measures of physiology, including estimation of metabolic rate, as well as heart rate and function, will advance our understanding of the causes and consequences of long lifespans. Determining the extent and effects of current threats (as well as potential mitigation measures) will assist the development of policies, recommendations, and actions relevant for the management of this potentially vulnerable species. Through an interdisciplinary lens, we propose innovative approaches to direct the future study of Greenland sharks and promote the consideration of longevity as an important factor in research on aquatic and terrestrial predators.",
    url = "https://doi.org/10.3389/fmars.2019.00087",
    doi = "10.3389/fmars.2019.00087",
    openalex = "W2929063046",
    references = "doi101017s0376892909990191"
}

@article{doi101016jzool2020125799,
    author = "Sternes, Phillip C. and Shimada, Kenshu",
    title = "Body forms in sharks (Chondrichthyes: Elasmobranchii) and their functional, ecological, and evolutionary implications",
    year = "2020",
    journal = "Zoology",
    url = "https://doi.org/10.1016/j.zool.2020.125799",
    doi = "10.1016/j.zool.2020.125799",
    openalex = "W3020558602",
    references = "doi101007s0042701605392, doi101007s116920099055x, doi101016016953479390024j, doi101016c20100662092, doi101093icb241107, doi10110948757275, doi101111j10958649201203245x, doi101111j17550998201002924x, doi101201b118678, doi104404hystrix26111264, doi105860choice295104, doi107554elife00590, openalexw641496887"
}

Inferring the size of extinct animals is fraught with danger, especially when they were much larger than their modern relatives. Such extrapolations are particularly risky when allometry is present. The extinct giant shark †Otodus megalodon is known almost exclusively from fossilised teeth. Estimates of †O. megalodon body size have been made from its teeth, using the great white shark (Carcharodon carcharias) as the only modern analogue. This can be problematic as the two species likely belong to different families, and the position of the †Otodus lineage within Lamniformes is unclear. Here, we infer †O. megalodon body dimensions based on anatomical measurements of five ecologically and physiologically similar extant lamniforms: Carcharodon carcharias, Isurus oxyrinchus, Isurus paucus, Lamna ditropis and Lamna nasus. We first assessed for allometry in all analogues using linear regressions and geometric morphometric analyses. Finding no evidence of allometry, we made morphological extrapolations to infer body dimensions of †O. megalodon at different sizes. Our results suggest that a 16 m †O. megalodon likely had a head ~ 4.65 m long, a dorsal fin ~ 1.62 m tall and a tail ~ 3.85 m high. Morphometric analyses further suggest that its dorsal and caudal fins were adapted for swift predatory locomotion and long-swimming periods.

@article{doi101038s4159802071387y,
    author = "Cooper, Jack A. and Pimiento, Catalina and Ferrón, Humberto G. and Benton, Michael J.",
    title = "Body dimensions of the extinct giant shark Otodus megalodon: a 2D reconstruction",
    year = "2020",
    journal = "Scientific Reports",
    abstract = "Inferring the size of extinct animals is fraught with danger, especially when they were much larger than their modern relatives. Such extrapolations are particularly risky when allometry is present. The extinct giant shark †Otodus megalodon is known almost exclusively from fossilised teeth. Estimates of †O. megalodon body size have been made from its teeth, using the great white shark (Carcharodon carcharias) as the only modern analogue. This can be problematic as the two species likely belong to different families, and the position of the †Otodus lineage within Lamniformes is unclear. Here, we infer †O. megalodon body dimensions based on anatomical measurements of five ecologically and physiologically similar extant lamniforms: Carcharodon carcharias, Isurus oxyrinchus, Isurus paucus, Lamna ditropis and Lamna nasus. We first assessed for allometry in all analogues using linear regressions and geometric morphometric analyses. Finding no evidence of allometry, we made morphological extrapolations to infer body dimensions of †O. megalodon at different sizes. Our results suggest that a 16 m †O. megalodon likely had a head \textasciitilde\ 4.65 m long, a dorsal fin \textasciitilde\ 1.62 m tall and a tail \textasciitilde\ 3.85 m high. Morphometric analyses further suggest that its dorsal and caudal fins were adapted for swift predatory locomotion and long-swimming periods.",
    url = "https://doi.org/10.1038/s41598-020-71387-y",
    doi = "10.1038/s41598-020-71387-y",
    openalex = "W3048588243",
    references = "doi101007bf01821211, doi101007s0022700603251, doi101007s1091401191701, doi1010800891296320191666840, doi101111j155856461998tb02018x, doi101111j17550998201002924x, doi101371journalpone0185185, doi10166612117, doi10189000129658200687829uoiaov20co2, doi1023072411306, doi105962bhltitle4275, openalexw2138825607, openalexw570265017"
}

Species diversity assessments are an important step to evaluate the conservation status of a community, both in marine and terrestrial ecosystems. These assessments are pivotal if related to both, the constant increase of human pressure on ecosystems and the anthropogenic climate change occurring nowadays. Sharks and rays are globally threatened, and the situation is particularly alarming in the Mediterranean Sea where more than 50% of species are listed at risk of extinction by the International Union for Conservation of Nature (IUCN). In this paper, we revise and discuss the chondrichthyan species richness of the Mediterranean and the Black Sea. Through an accurate review of published taxonomic studies, historical data on species occurrence, analyses of scientific survey data and biodiversity databases and other scientific papers, we produced a revised list of species whose presence in the Mediterranean Sea is confirmed or highly probable and discussed on current taxonomic and occurrence disputes on the species that are instead rarer or claimed to be locally extinct. We listed a total of 88 species, representing 30 families and 48 genera that are currently present in the Mediterranean and the Black Sea. This number includes 48 shark species, 38 batoids, and 2 chimaeras. The review represents a reference for future conservation assessments of cartilaginous fish in the region and a guide for decision-makers when promoting the sustainable exploitation of fisheries resource within an ecosystem-based framework. This paper can help to set a baseline of the Mediterranean species and thus resolve some uncertainties regarding their conservation status, explaining the reasons for their prolonged absence in the reports. Indeed, failure to record over time may not be due to grubbing up, but because after careful review this species was not really part of the Mediterranean fauna.

@article{doi1010802475026320201805518,
    author = "Serena, Fabrizio and Abella, A. and Bargnesi, Filippo and Barone, Monica and Colloca, Francesco and Ferretti, Francesco and Fiorentino, Fabio and Jenrette, J. and Moro, Stefano",
    title = "Species diversity, taxonomy and distribution of Chondrichthyes in the Mediterranean and Black Sea",
    year = "2020",
    journal = "The European Zoological Journal",
    abstract = "Species diversity assessments are an important step to evaluate the conservation status of a community, both in marine and terrestrial ecosystems. These assessments are pivotal if related to both, the constant increase of human pressure on ecosystems and the anthropogenic climate change occurring nowadays. Sharks and rays are globally threatened, and the situation is particularly alarming in the Mediterranean Sea where more than 50\% of species are listed at risk of extinction by the International Union for Conservation of Nature (IUCN). In this paper, we revise and discuss the chondrichthyan species richness of the Mediterranean and the Black Sea. Through an accurate review of published taxonomic studies, historical data on species occurrence, analyses of scientific survey data and biodiversity databases and other scientific papers, we produced a revised list of species whose presence in the Mediterranean Sea is confirmed or highly probable and discussed on current taxonomic and occurrence disputes on the species that are instead rarer or claimed to be locally extinct. We listed a total of 88 species, representing 30 families and 48 genera that are currently present in the Mediterranean and the Black Sea. This number includes 48 shark species, 38 batoids, and 2 chimaeras. The review represents a reference for future conservation assessments of cartilaginous fish in the region and a guide for decision-makers when promoting the sustainable exploitation of fisheries resource within an ecosystem-based framework. This paper can help to set a baseline of the Mediterranean species and thus resolve some uncertainties regarding their conservation status, explaining the reasons for their prolonged absence in the reports. Indeed, failure to record over time may not be due to grubbing up, but because after careful review this species was not really part of the Mediterranean fauna.",
    url = "https://doi.org/10.1080/24750263.2020.1805518",
    doi = "10.1080/24750263.2020.1805518",
    openalex = "W3093967901",
    references = "doi101111j10958649201203264x, doi101111jfb12874, doi1011646zootaxa375215, openalexw2900647185"
}

of Jervis Bay sharks was greater than that of Adelaide sharks. This indicates that the energetics of cooler water population (Adelaide) is likely more thermally sensitive than that of the warmer population (Jervis Bay). While unique to elasmobranchs, these data provide further support that by treating species as static, homogeneous populations, we ignore the impacts of thermal history and intraspecific variation on thermal sensitivity. With climate change, intraspecific variation will manifest as populations move, demographics change or extirpations occur, starting with the most sensitive populations.

@article{doi101111gcb15422,
    author = "Gervais, Connor R. and Huveneers, Charlie and Rummer, Jodie L. and Brown, Culum",
    title = "Population variation in the thermal response to climate change reveals differing sensitivity in a benthic shark",
    year = "2020",
    journal = "Global Change Biology",
    abstract = "of Jervis Bay sharks was greater than that of Adelaide sharks. This indicates that the energetics of cooler water population (Adelaide) is likely more thermally sensitive than that of the warmer population (Jervis Bay). While unique to elasmobranchs, these data provide further support that by treating species as static, homogeneous populations, we ignore the impacts of thermal history and intraspecific variation on thermal sensitivity. With climate change, intraspecific variation will manifest as populations move, demographics change or extirpations occur, starting with the most sensitive populations.",
    url = "https://doi.org/10.1111/gcb.15422",
    doi = "10.1111/gcb.15422",
    openalex = "W3096342365",
    references = "doi101007s11160020096040, wheeler2020anthropogenic"
}

A refuge can be any space that keeps an organism safe from danger. Prey usually seek protection in the closest refuge available to minimize cost while maximizing survival. Aerial drone footage of blacktip sharks, Carcharhinus limbatus, along the coast of southeast Florida, USA, shows adult blacktips fleeing to the shallow water adjacent to the beach when confronted with or chased by a predatory great hammerhead shark, Sphyrna mokarran. To authors' knowledge, this is the first evidence of adult C. limbatus using shallow waters as a refuge.

@article{doi101111jfb14342,
    author = "Doan, Melanie D. and Kajiura, Stephen M.",
    title = "Adult blacktip sharks (Carcharhinus limbatus) use shallow water as a refuge from great hammerheads (Sphyrna mokarran)",
    year = "2020",
    journal = "Journal of Fish Biology",
    abstract = "A refuge can be any space that keeps an organism safe from danger. Prey usually seek protection in the closest refuge available to minimize cost while maximizing survival. Aerial drone footage of blacktip sharks, Carcharhinus limbatus, along the coast of southeast Florida, USA, shows adult blacktips fleeing to the shallow water adjacent to the beach when confronted with or chased by a predatory great hammerhead shark, Sphyrna mokarran. To authors' knowledge, this is the first evidence of adult C. limbatus using shallow waters as a refuge.",
    url = "https://doi.org/10.1111/jfb.14342",
    doi = "10.1111/jfb.14342",
    openalex = "W3015290634",
    references = "doi101201b118678"
}

Conservation and management measures for large mobile sharks are more effective when information on migratory patterns and environmental cues are known. In the absence of long-term monitoring data or tracking programs, available information is based on occasional catch or sighting records from a variety of sources, usually constrained in space and time. This study demonstrates the utility of developing temporally explicit habitat suitability (HS) models to infer the migratory pattern of large mobile sharks. Bimonthly presence-only HS models (MaxEnt algorithm) were developed for the broadnose sevengill shark (Notorynchus cepedianus) in the southwest Atlantic based on an exhaustive collection of data records and ecologically relevant predictors. The six final models showed good predictive power and were evaluated with independent data. A migratory pattern characterized by two main displacements was inferred from the models. We show that HS models can be applied as a no-cost, desk-based alternative to infer broadscale movements of large mobile sharks. This methodology is relevant as an important first step toward informing management plans in data-poor and financially limited regions or regions under urgent conservation need.

@article{doi101139cjfas20200036,
    author = "Wysiecki, Agustín M. De and Sánchez‐Carnero, Noela and Irigoyen, Alejo J. and Milessi, Andrés C. and Colonello, Jorge H. and Bovcon, Nelson D. and Cortés, Federico and Barbini, Santiago A. and Cedrola, Paula V. and Coller, Nidia Marina and Jaureguizar, Andrés J.",
    title = "Using temporally explicit habitat suitability models to infer the migratory pattern of a large mobile shark",
    year = "2020",
    journal = "Canadian Journal of Fisheries and Aquatic Sciences",
    abstract = "Conservation and management measures for large mobile sharks are more effective when information on migratory patterns and environmental cues are known. In the absence of long-term monitoring data or tracking programs, available information is based on occasional catch or sighting records from a variety of sources, usually constrained in space and time. This study demonstrates the utility of developing temporally explicit habitat suitability (HS) models to infer the migratory pattern of large mobile sharks. Bimonthly presence-only HS models (MaxEnt algorithm) were developed for the broadnose sevengill shark (Notorynchus cepedianus) in the southwest Atlantic based on an exhaustive collection of data records and ecologically relevant predictors. The six final models showed good predictive power and were evaluated with independent data. A migratory pattern characterized by two main displacements was inferred from the models. We show that HS models can be applied as a no-cost, desk-based alternative to infer broadscale movements of large mobile sharks. This methodology is relevant as an important first step toward informing management plans in data-poor and financially limited regions or regions under urgent conservation need.",
    url = "https://doi.org/10.1139/cjfas-2020-0036",
    doi = "10.1139/cjfas-2020-0036",
    openalex = "W3034453879",
    references = "doi101007s1053101101897, doi101016jecolmodel200503026, doi101038s41598017177655, doi101111ecog01132, doi101111ecog03049, doi101111j0906759020085203x, doi101111j14724642201000725x, doi101111j16000587201307872x, doi101146annurevecolsys110308120159, doi1018900721531, doi1018901011711"
}

Many important areas identified for conservation priorities focus on areas of high species richness, however, it is unclear whether these areas change depending on what aspect of richness is considered (e.g. evolutionary distinctiveness, endemicity, or threatened species). Furthermore, little is known of the extent of spatial congruency between biodiversity measures in the marine realm. Here, we used the distribution maps of all known marine sharks, rays, and chimaeras (class Chondrichthyes) to examine the extent of spatial congruency across the hotspots of three measures of species richness: total number of species, evolutionarily distinct species, and endemic species. We assessed the spatial congruency between hotspots considering all species, as well as on the subset of the threatened species only. We consider three definitions of hotspot (2.5%, 5%, and 10% of cells with the highest numbers of species) and three levels of spatial resolution (1, 4, and 8grid cells). Overall, we found low congruency among all three measures of species richness, with the threatened species comprising a smaller subset of the overall species patterns irrespective of hotspot definition. Areas of congruency at 1and 5% richest cells contain over half (64%) of all sharks and rays and occurred off the coasts of: (1) Northern Mexico Gulf of California, (2) USA Gulf of Mexico, (3) Ecuador, (4) Uruguay and southern Brazil, (5) South Africa, southern Mozambique, and southern Namibia, (6) Japan, Taiwan, and parts of southern China, and (7) eastern and western Australia. Coarsening resolution increases congruency twofold for all species but remains relatively low for threatened measures, and geographic locations of congruent areas also change. Finally, for pairwise comparisons of biodiversity measures, evolutionarily distinct species richness had the highest overlap with total species richness regardless of resolution or definition of hotspot. We suggest that focusing conservation attention solely on areas of high total species richness will not necessarily contribute efforts towards species that are most at risk, nor will it protect other important dimensions of species richness.

@article{doi101371journalpone0235559,
    author = "Derrick, Danielle H. and Cheok, Jessica and Dulvy, Nicholas K.",
    title = "Spatially congruent sites of importance for global shark and ray biodiversity",
    year = "2020",
    journal = "PLoS ONE",
    abstract = "Many important areas identified for conservation priorities focus on areas of high species richness, however, it is unclear whether these areas change depending on what aspect of richness is considered (e.g. evolutionary distinctiveness, endemicity, or threatened species). Furthermore, little is known of the extent of spatial congruency between biodiversity measures in the marine realm. Here, we used the distribution maps of all known marine sharks, rays, and chimaeras (class Chondrichthyes) to examine the extent of spatial congruency across the hotspots of three measures of species richness: total number of species, evolutionarily distinct species, and endemic species. We assessed the spatial congruency between hotspots considering all species, as well as on the subset of the threatened species only. We consider three definitions of hotspot (2.5\%, 5\%, and 10\% of cells with the highest numbers of species) and three levels of spatial resolution (1, 4, and 8grid cells). Overall, we found low congruency among all three measures of species richness, with the threatened species comprising a smaller subset of the overall species patterns irrespective of hotspot definition. Areas of congruency at 1and 5\% richest cells contain over half (64\%) of all sharks and rays and occurred off the coasts of: (1) Northern Mexico Gulf of California, (2) USA Gulf of Mexico, (3) Ecuador, (4) Uruguay and southern Brazil, (5) South Africa, southern Mozambique, and southern Namibia, (6) Japan, Taiwan, and parts of southern China, and (7) eastern and western Australia. Coarsening resolution increases congruency twofold for all species but remains relatively low for threatened measures, and geographic locations of congruent areas also change. Finally, for pairwise comparisons of biodiversity measures, evolutionarily distinct species richness had the highest overlap with total species richness regardless of resolution or definition of hotspot. We suggest that focusing conservation attention solely on areas of high total species richness will not necessarily contribute efforts towards species that are most at risk, nor will it protect other important dimensions of species richness.",
    url = "https://doi.org/10.1371/journal.pone.0235559",
    doi = "10.1371/journal.pone.0235559",
    openalex = "W3040232805",
    references = "doi101007s1053101101897"
}

The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes-sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species were threatened. Now, 391 (32.6%) species are threatened with extinction. When this percentage of threat is applied to Data Deficient species, more than one-third (37.5%) of chondrichthyans are estimated to be threatened, with much of this change resulting from new information. Three species are Critically Endangered (Possibly Extinct), representing possibly the first global marine fish extinctions due to overfishing. Consequently, the chondrichthyan extinction rate is potentially 25 extinctions per million species years, comparable to that of terrestrial vertebrates. Overfishing is the universal threat affecting all 391 threatened species and is the sole threat for 67.3% of species and interacts with three other threats for the remaining third: loss and degradation of habitat (31.2% of threatened species), climate change (10.2%), and pollution (6.9%). Species are disproportionately threatened in tropical and subtropical coastal waters. Science-based limits on fishing, effective marine protected areas, and approaches that reduce or eliminate fishing mortality are urgently needed to minimize mortality of threatened species and ensure sustainable catch and trade of others. Immediate action is essential to prevent further extinctions and protect the potential for food security and ecosystem functions provided by this iconic lineage of predators.

@article{doi101016jcub202108062,
    author = "Dulvy, Nicholas K. and Pacoureau, Nathan and Rigby, Cassandra L. and Pollom, Riley A. and Jabado, Rima W. and Ebert, David A. and Finucci, Brittany and Pollock, Caroline M. and Cheok, Jessica and Derrick, Danielle H. and Herman, Katelyn B. and Sherman, C. Samantha and VanderWright, Wade J. and Lawson, Julia M. and Walls, Rachel H.L. and Carlson, John K. and Charvet, Patrícia and Bineesh, K. K. and Fernando, Daniel and Ralph, Gina M. and Matsushiba, Jay H. and Hilton‐Taylor, Craig and Fordham, Sonja V. and Simpfendorfer, Colin A.",
    title = "Overfishing drives over one-third of all sharks and rays toward a global extinction crisis",
    year = "2021",
    journal = "Current Biology",
    abstract = "The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes-sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24\%) of species were threatened. Now, 391 (32.6\%) species are threatened with extinction. When this percentage of threat is applied to Data Deficient species, more than one-third (37.5\%) of chondrichthyans are estimated to be threatened, with much of this change resulting from new information. Three species are Critically Endangered (Possibly Extinct), representing possibly the first global marine fish extinctions due to overfishing. Consequently, the chondrichthyan extinction rate is potentially 25 extinctions per million species years, comparable to that of terrestrial vertebrates. Overfishing is the universal threat affecting all 391 threatened species and is the sole threat for 67.3\% of species and interacts with three other threats for the remaining third: loss and degradation of habitat (31.2\% of threatened species), climate change (10.2\%), and pollution (6.9\%). Species are disproportionately threatened in tropical and subtropical coastal waters. Science-based limits on fishing, effective marine protected areas, and approaches that reduce or eliminate fishing mortality are urgently needed to minimize mortality of threatened species and ensure sustainable catch and trade of others. Immediate action is essential to prevent further extinctions and protect the potential for food security and ecosystem functions provided by this iconic lineage of predators.",
    url = "https://doi.org/10.1016/j.cub.2021.08.062",
    doi = "10.1016/j.cub.2021.08.062",
    openalex = "W3197252187",
    references = "doi101016jtree200310013, doi101038536143a, doi101038nature09678, doi101038nature13022, doi101038nature14258, doi101093bioinformaticsbti623, doi101111j15231739200801044x, doi101126science1128035, doi101126science1194442, doi101126science1239352, doi107554elife00590"
}

Sharks are iconic predators in today's oceans, yet their modern diversity has ancient origins. In particular, present hypotheses suggest that a combination of mass extinction, global climate change, and competition has regulated the community structure of dominant mackerel (Lamniformes) and ground (Carcharhiniformes) sharks over the last 66 million years. However, while these scenarios advocate an interplay of major abiotic and biotic events, the precise drivers remain obscure. Here, we focus on the role of feeding ecology using a geometric morphometric analysis of 3,837 fossil and extant shark teeth. Our results reveal that morphological segregation rather than competition has characterized lamniform and carcharhiniform evolution. Moreover, although lamniforms suffered a long-term disparity decline potentially linked to dietary "specialization," their recent disparity rivals that of "generalist" carcharhiniforms. We further confirm that low eustatic sea levels impacted lamniform disparity across the end-Cretaceous mass extinction. Adaptations to changing prey availability and the proliferation of coral reef habitats during the Paleogene also likely facilitated carcharhiniform dispersals and cladogenesis, underpinning their current taxonomic dominance. Ultimately, we posit that trophic partitioning and resource utilization shaped past shark ecology and represent critical determinants for their future species survivorship.

@article{doi101016jcub202109028,
    author = "Bazzi, Mohamad and Campione, Nicolás E. and Kear, Benjamin P. and Pimiento, Catalina and Ahlberg, Per",
    title = "Feeding ecology has shaped the evolution of modern sharks",
    year = "2021",
    journal = "Current Biology",
    abstract = {Sharks are iconic predators in today's oceans, yet their modern diversity has ancient origins. In particular, present hypotheses suggest that a combination of mass extinction, global climate change, and competition has regulated the community structure of dominant mackerel (Lamniformes) and ground (Carcharhiniformes) sharks over the last 66 million years. However, while these scenarios advocate an interplay of major abiotic and biotic events, the precise drivers remain obscure. Here, we focus on the role of feeding ecology using a geometric morphometric analysis of 3,837 fossil and extant shark teeth. Our results reveal that morphological segregation rather than competition has characterized lamniform and carcharhiniform evolution. Moreover, although lamniforms suffered a long-term disparity decline potentially linked to dietary "specialization," their recent disparity rivals that of "generalist" carcharhiniforms. We further confirm that low eustatic sea levels impacted lamniform disparity across the end-Cretaceous mass extinction. Adaptations to changing prey availability and the proliferation of coral reef habitats during the Paleogene also likely facilitated carcharhiniform dispersals and cladogenesis, underpinning their current taxonomic dominance. Ultimately, we posit that trophic partitioning and resource utilization shaped past shark ecology and represent critical determinants for their future species survivorship.},
    url = "https://doi.org/10.1016/j.cub.2021.09.028",
    doi = "10.1016/j.cub.2021.09.028",
    openalex = "W3133227471",
    references = "doi101111j10958649201203245x, doi107717peerj6088"
}

@article{doi101038s41586020031739,
    author = "Pacoureau, Nathan and Rigby, Cassandra L. and Kyne, Peter M. and Sherley, Richard B. and Winker, Henning and Carlson, John K. and Fordham, Sonja V. and Barreto, Rodrigo and Fernando, Daniel and Francis, Malcolm P. and Jabado, Rima W. and Herman, Katelyn B. and Liu, Kwang-Ming and Marshall, Andrea D. and Pollom, Riley A. and Romanov, Evgeny V. and Simpfendorfer, Colin A. and Yin, Jamie S. and Kindsvater, Holly K. and Dulvy, Nicholas K.",
    title = "Half a century of global decline in oceanic sharks and rays",
    year = "2021",
    journal = "Nature",
    url = "https://doi.org/10.1038/s41586-020-03173-9",
    doi = "10.1038/s41586-020-03173-9",
    openalex = "W3122145272",
    references = "doi101038s4155901704484"
}

Climate change is affecting thermal regimes globally, and organisms relying on their environment to regulate biological processes face unknown consequences. In ectotherms, temperature affects development rates, body condition, and performance. Embryonic stages may be the most vulnerable life history stages, especially for oviparous species already living at the warm edge of their distribution, as embryos cannot relocate during this developmental window. We reared 27 epaulette shark (Hemiscyllium ocellatum) embryos under average summer conditions (27 °C) or temperatures predicted for the middle and end of the twenty-first century with climate change (i.e., 29 and 31 °C) and tracked growth, development, and metabolic costs both in ovo and upon hatch. Rearing sharks at 31 °C impacted embryonic growth, yolk consumption, and metabolic rates. Upon hatch, 31 °C-reared sharks weighed significantly less than their 27 °C-reared counterparts and exhibited reduced metabolic performance. Many important growth and development traits in this species may peak after 27 °C and start to become negatively impacted nearing 31 °C. We hypothesize that 31 °C approximates the pejus temperature (i.e., temperatures at which performance of a trait begin to decline) for this species, which is alarming, given that this temperature range is well within ocean warming scenarios predicted for this species' distribution over the next century.

@article{doi101038s41598020799530,
    author = "Wheeler, Carolyn R. and Rummer, Jodie L. and Bailey, Barbara and Lockwood, Jamie and Vance, Shelby and Mandelman, John W.",
    title = "Future thermal regimes for epaulette sharks (Hemiscyllium ocellatum): growth and metabolic performance cease to be optimal",
    year = "2021",
    journal = "Scientific Reports",
    abstract = "Climate change is affecting thermal regimes globally, and organisms relying on their environment to regulate biological processes face unknown consequences. In ectotherms, temperature affects development rates, body condition, and performance. Embryonic stages may be the most vulnerable life history stages, especially for oviparous species already living at the warm edge of their distribution, as embryos cannot relocate during this developmental window. We reared 27 epaulette shark (Hemiscyllium ocellatum) embryos under average summer conditions (27 °C) or temperatures predicted for the middle and end of the twenty-first century with climate change (i.e., 29 and 31 °C) and tracked growth, development, and metabolic costs both in ovo and upon hatch. Rearing sharks at 31 °C impacted embryonic growth, yolk consumption, and metabolic rates. Upon hatch, 31 °C-reared sharks weighed significantly less than their 27 °C-reared counterparts and exhibited reduced metabolic performance. Many important growth and development traits in this species may peak after 27 °C and start to become negatively impacted nearing 31 °C. We hypothesize that 31 °C approximates the pejus temperature (i.e., temperatures at which performance of a trait begin to decline) for this species, which is alarming, given that this temperature range is well within ocean warming scenarios predicted for this species' distribution over the next century.",
    url = "https://doi.org/10.1038/s41598-020-79953-0",
    doi = "10.1038/s41598-020-79953-0",
    openalex = "W3119565892",
    references = "doi101007s11160020096040, wheeler2020anthropogenic"
}

Climate change is altering distributions and abundances of marine species through both gradual and acute changes in temperature and productivity. Due to their high mobility and metabolic rates, elasmobranchs (sharks and rays) are likely to redistribute across latitudes and depths as they thermoregulate, but little is known about their responses to these climatic changes, which could vary widely across this diverse group of species. Here, we assessed how species with differing mobility and ecology responded to gradual changes in daily sea surface temperature (SST) and acute temperature anomalies, caused by the El Niño-Southern Oscillation (ENSO), at Cocos Island, Costa Rica, the site of multiple marine heatwaves. We used generalized linear mixed models to analyse 34,342 records of relative abundance or frequency of occurrence for seven shark and ray species collected in 27 years (1993-2019) by a dive company. We compared effect sizes for SST and the Oceanic Niño Index across the different species, which vary widely in body size and mobility. Large, mobile species responded strongly but inconsistently to temperature. For scalloped hammerhead sharks Sphyrna lewini, a 1℃ rise in SST reduced counts by over 14%, and dropped the occurrence of their large schools by almost one-fifth (19.4%). Mobula ray occurrence also declined substantially with a few degrees rise in SST, whereas tiger shark Galeocerdo cuvier occurrence sharply increased. These species also had divergent responses to the ENSO: S. lewini and G. cuvier were sighted with greater frequency during La Niña events, and their abundance dropped considerably during El Niño events-over a twofold decline between a strong La Niña and strong El Niño for S. lewini. In contrast, Mobula rays showed little response to ENSO. The smaller and sedentary Triaenodon obesus exhibited the weakest response of all species to both SST and the ENSO, reflecting its lower metabolic rates and mobility. Climate change will continue to impact elasmobranchs, even for smaller and more localized species, with the potential to impact the effectiveness of marine protected areas (MPAs). Our results compel further work on the diversity of elasmobranch responses to environmental change.

@article{doi1011111365265613560,
    author = "Osgood, Geoffrey J. and White, Easton R. and Baum, Julia K.",
    title = "Effects of climate‐change‐driven gradual and acute temperature changes on shark and ray species",
    year = "2021",
    journal = "Journal of Animal Ecology",
    abstract = "Climate change is altering distributions and abundances of marine species through both gradual and acute changes in temperature and productivity. Due to their high mobility and metabolic rates, elasmobranchs (sharks and rays) are likely to redistribute across latitudes and depths as they thermoregulate, but little is known about their responses to these climatic changes, which could vary widely across this diverse group of species. Here, we assessed how species with differing mobility and ecology responded to gradual changes in daily sea surface temperature (SST) and acute temperature anomalies, caused by the El Niño-Southern Oscillation (ENSO), at Cocos Island, Costa Rica, the site of multiple marine heatwaves. We used generalized linear mixed models to analyse 34,342 records of relative abundance or frequency of occurrence for seven shark and ray species collected in 27 years (1993-2019) by a dive company. We compared effect sizes for SST and the Oceanic Niño Index across the different species, which vary widely in body size and mobility. Large, mobile species responded strongly but inconsistently to temperature. For scalloped hammerhead sharks Sphyrna lewini, a 1℃ rise in SST reduced counts by over 14\%, and dropped the occurrence of their large schools by almost one-fifth (19.4\%). Mobula ray occurrence also declined substantially with a few degrees rise in SST, whereas tiger shark Galeocerdo cuvier occurrence sharply increased. These species also had divergent responses to the ENSO: S. lewini and G. cuvier were sighted with greater frequency during La Niña events, and their abundance dropped considerably during El Niño events-over a twofold decline between a strong La Niña and strong El Niño for S. lewini. In contrast, Mobula rays showed little response to ENSO. The smaller and sedentary Triaenodon obesus exhibited the weakest response of all species to both SST and the ENSO, reflecting its lower metabolic rates and mobility. Climate change will continue to impact elasmobranchs, even for smaller and more localized species, with the potential to impact the effectiveness of marine protected areas (MPAs). Our results compel further work on the diversity of elasmobranch responses to environmental change.",
    url = "https://doi.org/10.1111/1365-2656.13560",
    doi = "10.1111/1365-2656.13560",
    openalex = "W3170086295",
    references = "doi101007s106410140294z"
}

Abstract Globally, one quarter of shark and ray species are threatened with extinction due to overfishing. Effective conservation and management can facilitate population recoveries. However, these efforts depend on robust data on movement patterns and stock structure, which are lacking for many threatened species, including the Critically Endangered soupfin shark Galeorhinus galeus, a circumglobal coastal‐pelagic species. Using passive acoustic telemetry, we continuously tracked 34 mature female soupfin sharks, surgically implanted with coded acoustic transmitters, for 7 years via 337 underwater acoustic receivers stationed along the west coast of North America. These sharks and an additional six were also externally fitted with spaghetti identification tags. Our tagging site was a shallow rocky reef off La Jolla (San Diego County), California, USA, where adult females were observed to aggregate every summer. Tagged soupfin sharks were highly migratory along the west coast of North America, between Washington, USA and Baja California Sur, Mexico. However, every 3 years, they returned to waters off La Jolla, California, where they underwent gestation. This is the first conclusive evidence of triennial migration and philopatry (‘home‐loving’) in any animal, which is apparently driven by this species’ unusual triennial reproductive cycle. Females of other shark and ray species with triennial reproductive cycles are also likely to exhibit triennial cycles of migration and philopatry. At least six (15%) of our tagged soupfin sharks were killed in commercial gillnets in Mexico. Policy implications. Identifying multiennial migratory cycles in mature female sharks can reveal hidden stock structure in the form of discrete breeding cohorts, which are spatially and temporally segregated as they cycle through different reproductive phases. Accounting for this complexity may improve the performance of spatially structured stock assessment models, particularly when fishery removals are spatially heterogeneous, as well as inform the spatiotemporal design of fishery‐independent surveys. In the United States, the soupfin shark is neither actively managed nor recognized as a Highly Migratory Species; however, given the highly migratory behaviour we report, this designation should be revisited by the US Pacific Fishery Management Council. Finally, given the extensive fishery removals in Mexico, any future management must be internationally cooperative.

@article{doi1011111365266413848,
    author = "Nosal, Andrew P. and Cartamil, Daniel P. and Ammann, Arnold J. and Bellquist, Lyall and Ben‐Aderet, Noah and Blincow, Kayla M. and Burns, Echelle S. and Chapman, Eric D. and Freedman, R. and Klimley, A. Peter and Logan, Ryan K. and Lowe, Christopher G. and Semmens, Brice X. and White, Connor F. and Hastings, Philip A.",
    title = "Triennial migration and philopatry in the critically endangered soupfin shark Galeorhinus galeus",
    year = "2021",
    journal = "Journal of Applied Ecology",
    abstract = "Abstract Globally, one quarter of shark and ray species are threatened with extinction due to overfishing. Effective conservation and management can facilitate population recoveries. However, these efforts depend on robust data on movement patterns and stock structure, which are lacking for many threatened species, including the Critically Endangered soupfin shark Galeorhinus galeus, a circumglobal coastal‐pelagic species. Using passive acoustic telemetry, we continuously tracked 34 mature female soupfin sharks, surgically implanted with coded acoustic transmitters, for 7 years via 337 underwater acoustic receivers stationed along the west coast of North America. These sharks and an additional six were also externally fitted with spaghetti identification tags. Our tagging site was a shallow rocky reef off La Jolla (San Diego County), California, USA, where adult females were observed to aggregate every summer. Tagged soupfin sharks were highly migratory along the west coast of North America, between Washington, USA and Baja California Sur, Mexico. However, every 3 years, they returned to waters off La Jolla, California, where they underwent gestation. This is the first conclusive evidence of triennial migration and philopatry (‘home‐loving’) in any animal, which is apparently driven by this species’ unusual triennial reproductive cycle. Females of other shark and ray species with triennial reproductive cycles are also likely to exhibit triennial cycles of migration and philopatry. At least six (15\%) of our tagged soupfin sharks were killed in commercial gillnets in Mexico. Policy implications. Identifying multiennial migratory cycles in mature female sharks can reveal hidden stock structure in the form of discrete breeding cohorts, which are spatially and temporally segregated as they cycle through different reproductive phases. Accounting for this complexity may improve the performance of spatially structured stock assessment models, particularly when fishery removals are spatially heterogeneous, as well as inform the spatiotemporal design of fishery‐independent surveys. In the United States, the soupfin shark is neither actively managed nor recognized as a Highly Migratory Species; however, given the highly migratory behaviour we report, this designation should be revisited by the US Pacific Fishery Management Council. Finally, given the extensive fishery removals in Mexico, any future management must be internationally cooperative.",
    url = "https://doi.org/10.1111/1365-2664.13848",
    doi = "10.1111/1365-2664.13848",
    openalex = "W3134617324",
    references = "doi101016b9780128096338206031"
}

Over the past 4 decades there has been a growing concern for the conservation status of elasmobranchs (sharks and rays). In 2002, the first elasmobranch species were added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Less than 20 yr later, there were 39 species on Appendix II and 5 on Appendix I. Despite growing concern, effective conservation and management remain challenged by a lack of data on population status for many species, human−wildlife interactions, threats to population viability, and the efficacy of conservation approaches. We surveyed 100 of the most frequently published and cited experts on elasmobranchs and, based on ranked responses, prioritized 20 research questions on elasmobranch conservation. To address these questions, we then convened a group of 47 experts from 35 institutions and 12 countries. The 20 questions were organized into the following broad categories: (1) status and threats, (2) population and ecology, and (3) conservation and management. For each section, we sought to synthesize existing knowledge, describe consensus or diverging views, identify gaps, and suggest promising future directions and research priorities. The resulting synthesis aggregates an array of perspectives on emergent research and priority directions for elasmobranch conservation.

@article{doi103354esr01169,
    author = "Jorgensen, SJ and Micheli, Fiorenza and White, T D and Houtan, Kyle S. Van and Alfaro‐Shigueto, Joanna and Andrzejaczek, Samantha and Arnoldi, Natalie S. and Baum, Julia K. and Block, Barbara A. and Britten, GL and Butner, Cheryl and Caballero, Susana and Cardeñosa, Diego and Chapple, TK and Clarke, S. and Cortés, Enric and Dulvy, Nicholas K. and Fowler, S. and Gallagher, AJ and Gilman, Eric and Godley, Brendan J. and Graham, RT and Hammerschlag, Neil and Harry, AV and Heithaus, Michael R. and Hutchinson, Melanie and Huveneers, Charlie and Lowe, CG and Lucifora, Luis O. and MacKeracher, Tracy and Mangel, Jeffrey C. and Martins, Ana Paula Barbosa and McCauley, DJ and McClenachan, Loren and Mull, Christopher G. and Natanson, LJ and Pauly, Daniel and Pazmiño, DA and Pistevos, JCA and Queiroz, Nuno and Roff, George and Shea, BD and Simpfendorfer, Colin A. and Sims, DW and Ward‐Paige, Christine A. and Worm, Boris and Ferretti, Francesco",
    title = "Emergent research and priorities for shark and ray conservation",
    year = "2021",
    journal = "Endangered Species Research",
    abstract = "Over the past 4 decades there has been a growing concern for the conservation status of elasmobranchs (sharks and rays). In 2002, the first elasmobranch species were added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Less than 20 yr later, there were 39 species on Appendix II and 5 on Appendix I. Despite growing concern, effective conservation and management remain challenged by a lack of data on population status for many species, human−wildlife interactions, threats to population viability, and the efficacy of conservation approaches. We surveyed 100 of the most frequently published and cited experts on elasmobranchs and, based on ranked responses, prioritized 20 research questions on elasmobranch conservation. To address these questions, we then convened a group of 47 experts from 35 institutions and 12 countries. The 20 questions were organized into the following broad categories: (1) status and threats, (2) population and ecology, and (3) conservation and management. For each section, we sought to synthesize existing knowledge, describe consensus or diverging views, identify gaps, and suggest promising future directions and research priorities. The resulting synthesis aggregates an array of perspectives on emergent research and priority directions for elasmobranch conservation.",
    url = "https://doi.org/10.3354/esr01169",
    doi = "10.3354/esr01169",
    openalex = "W3212659873",
    references = "doi101016jbiocon201502007, doi101016jcub202108062, doi101016jtree201602014, doi101038s4155901704484, doi101111j10958649201203265x, doi101643ot19179r"
}

Chondrichthyes (cartilaginous fishes) are fundamental for understanding vertebrate evolution, yet their genomes are understudied. We report long-read sequencing of the whale shark genome to generate the best gapless chondrichthyan genome assembly yet with higher contig contiguity than all other cartilaginous fish genomes, and studied vertebrate genomic evolution of ancestral gene families, immunity, and gigantism. We found a major increase in gene families at the origin of gnathostomes (jawed vertebrates) independent of their genome duplication. We studied vertebrate pathogen recognition receptors (PRRs), which are key in initiating innate immune defense, and found diverse patterns of gene family evolution, demonstrating that adaptive immunity in gnathostomes did not fully displace germline-encoded PRR innovation. We also discovered a new toll-like receptor (TLR29) and three NOD1 copies in the whale shark. We found chondrichthyan and giant vertebrate genomes had decreased substitution rates compared to other vertebrates, but gene family expansion rates varied among vertebrate giants, suggesting substitution and expansion rates of gene families are decoupled in vertebrate genomes. Finally, we found gene families that shifted in expansion rate in vertebrate giants were enriched for human cancer-related genes, consistent with gigantism requiring adaptations to suppress cancer.

@article{doi107554elife65394,
    author = "Tan, Milton and Redmond, Anthony K. and Dooley, Helen and Nozu, Ryo and Sato, Keiichi and Kuraku, Shigehiro and Koren, Sergey and Phillippy, Adam M. and Dove, Alistair D. M. and Read, Timothy D.",
    title = "The whale shark genome reveals patterns of vertebrate gene family evolution",
    year = "2021",
    journal = "eLife",
    abstract = "Chondrichthyes (cartilaginous fishes) are fundamental for understanding vertebrate evolution, yet their genomes are understudied. We report long-read sequencing of the whale shark genome to generate the best gapless chondrichthyan genome assembly yet with higher contig contiguity than all other cartilaginous fish genomes, and studied vertebrate genomic evolution of ancestral gene families, immunity, and gigantism. We found a major increase in gene families at the origin of gnathostomes (jawed vertebrates) independent of their genome duplication. We studied vertebrate pathogen recognition receptors (PRRs), which are key in initiating innate immune defense, and found diverse patterns of gene family evolution, demonstrating that adaptive immunity in gnathostomes did not fully displace germline-encoded PRR innovation. We also discovered a new toll-like receptor (TLR29) and three NOD1 copies in the whale shark. We found chondrichthyan and giant vertebrate genomes had decreased substitution rates compared to other vertebrates, but gene family expansion rates varied among vertebrate giants, suggesting substitution and expansion rates of gene families are decoupled in vertebrate genomes. Finally, we found gene families that shifted in expansion rate in vertebrate giants were enriched for human cancer-related genes, consistent with gigantism requiring adaptations to suppress cancer.",
    url = "https://doi.org/10.7554/elife.65394",
    doi = "10.7554/elife.65394",
    openalex = "W3194949746",
    references = "doi101038nature20806, doi101111evo13680"
}

Abstract Climate change stressors (e.g., warming and ocean acidification) are an imminent challenge to the physiological performance of marine organisms. Several studies spanning the last decade have reported widespread effects of warming and acidification on marine fishes, especially teleosts, but more work is needed to elucidate the responses in marine elasmobranchs, i.e., sharks and rays. Dispersal capacity, as a result of locomotor performance, is a crucial trait that will determine which group of elasmobranchs will be more or less vulnerable to changes in the environment. In fact, efficient and high locomotor performance may determine the capacity for elasmobranchs to relocate to a more favorable area. In this review we integrate findings from work on locomotion of marine sharks and rays to identify characteristics that outline potential vulnerabilities and strength of sharks and rays under climate change. Traits such as intraspecific variability in response to climatic stressors, wide geographic range, thermotaxis, fast swimming or low energetic costs of locomotion are likely to enhance the capacity to disperse. Future studies may focus on understanding the interacting effect of climatic stressors on morphology, biomechanics and energetics of steady and unsteady swimming, across ontogeny and species.

@article{doi101007s1116002209706x,
    author = "Vilmar, Matilda and Santo, Valentina Di",
    title = "Swimming performance of sharks and rays under climate change",
    year = "2022",
    journal = "Reviews in Fish Biology and Fisheries",
    abstract = "Abstract Climate change stressors (e.g., warming and ocean acidification) are an imminent challenge to the physiological performance of marine organisms. Several studies spanning the last decade have reported widespread effects of warming and acidification on marine fishes, especially teleosts, but more work is needed to elucidate the responses in marine elasmobranchs, i.e., sharks and rays. Dispersal capacity, as a result of locomotor performance, is a crucial trait that will determine which group of elasmobranchs will be more or less vulnerable to changes in the environment. In fact, efficient and high locomotor performance may determine the capacity for elasmobranchs to relocate to a more favorable area. In this review we integrate findings from work on locomotion of marine sharks and rays to identify characteristics that outline potential vulnerabilities and strength of sharks and rays under climate change. Traits such as intraspecific variability in response to climatic stressors, wide geographic range, thermotaxis, fast swimming or low energetic costs of locomotion are likely to enhance the capacity to disperse. Future studies may focus on understanding the interacting effect of climatic stressors on morphology, biomechanics and energetics of steady and unsteady swimming, across ontogeny and species.",
    url = "https://doi.org/10.1007/s11160-022-09706-x",
    doi = "10.1007/s11160-022-09706-x",
    openalex = "W4220835552",
    references = "doi101007s11160020096040, wheeler2020anthropogenic"
}

Estimating deep-time species-level diversification processes remains challenging. Both the fossil record and molecular phylogenies allow the estimation of speciation and extinction rates, but each type of data may still provide an incomplete picture of diversification dynamics. Here, we combine species-level palaeontological (fossil occurrences) and neontological (molecular phylogenies) data to estimate deep-time diversity dynamics through process-based birth-death models for Carcharhiniformes, the most speciose shark order today. Despite their abundant fossil record dating back to the Middle Jurassic, only a small fraction of extant carcharhiniform species is recorded as fossils, which impedes relying only on the fossil record to study their recent diversification. Combining fossil and phylogenetic data, we recover a complex evolutionary history for carcharhiniforms, exemplified by several variations in diversification rates with an early low diversity period followed by a Cenozoic radiation. We further reveal a burst of diversification in the last 30 million years, which is partially recorded with fossil data only. We also find that reef expansion and temperature change can explain variations in speciation and extinction through time. These results pinpoint the primordial importance of these environmental variables in the evolution of marine clades. Our study also highlights the benefit of combining the fossil record with phylogenetic data to address macroevolutionary questions.

@article{doi101038s41598022260107,
    author = "Brée, Baptiste and Condamine, Fabien L. and Guinot, Guillaume",
    title = "Combining palaeontological and neontological data shows a delayed diversification burst of carcharhiniform sharks likely mediated by environmental change",
    year = "2022",
    journal = "Scientific Reports",
    abstract = "Estimating deep-time species-level diversification processes remains challenging. Both the fossil record and molecular phylogenies allow the estimation of speciation and extinction rates, but each type of data may still provide an incomplete picture of diversification dynamics. Here, we combine species-level palaeontological (fossil occurrences) and neontological (molecular phylogenies) data to estimate deep-time diversity dynamics through process-based birth-death models for Carcharhiniformes, the most speciose shark order today. Despite their abundant fossil record dating back to the Middle Jurassic, only a small fraction of extant carcharhiniform species is recorded as fossils, which impedes relying only on the fossil record to study their recent diversification. Combining fossil and phylogenetic data, we recover a complex evolutionary history for carcharhiniforms, exemplified by several variations in diversification rates with an early low diversity period followed by a Cenozoic radiation. We further reveal a burst of diversification in the last 30 million years, which is partially recorded with fossil data only. We also find that reef expansion and temperature change can explain variations in speciation and extinction through time. These results pinpoint the primordial importance of these environmental variables in the evolution of marine clades. Our study also highlights the benefit of combining the fossil record with phylogenetic data to address macroevolutionary questions.",
    url = "https://doi.org/10.1038/s41598-022-26010-7",
    doi = "10.1038/s41598-022-26010-7",
    openalex = "W4312093714",
    references = "doi101002jmor1073, doi101038s41467021237540, doi101073pnas1902693116"
}

The late Neogene megatooth shark, Otodus megalodon, is known mainly from its gigantic teeth and possibly reached 18–20 m in total length (TL). We re-examine the previously proposed body size trends and nursery areas of O. megalodon by confining the previously used samples to upper anterior teeth offering more reliable TL estimates, and by taking paleolatitudes and sea-surface temperatures into consideration. We demonstrate that individuals of O. megalodon are on average larger in cooler water than those in warmer water – a pattern attributable to Bergmann’s rule showing a latitudinal body size gradient at least for the eastern Pacific late Miocene and the western Atlantic early Pliocene assemblages. While it is still possible that neonatal O. megalodon could have utilised nursery areas, the previously identified paleo-nursery areas based on body size may reflect temperature-dependent trends rather than the inferred reproductive strategy. Thus, the gigantism of O. megalodon in cooler waters was possibly further enhanced by its cooler environment. If so, the corollary of this study is that not all populations of O. megalodon likely grew to gigantic sizes equally, where the common notion that the species reached 18–20 m TL should be applied primarily to populations in cooler environments.

@article{doi1010800891296320222032024,
    author = "Shimada, Kenshu and Maisch, Harry M. and Pérez, Víctor Juan Ventosa and Becker, Martin A. and Griffiths, Michael L.",
    title = "Revisiting body size trends and nursery areas of the Neogene megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), reveals Bergmann’s rule possibly enhanced its gigantism in cooler waters",
    year = "2022",
    journal = "Historical Biology",
    abstract = "The late Neogene megatooth shark, Otodus megalodon, is known mainly from its gigantic teeth and possibly reached 18–20 m in total length (TL). We re-examine the previously proposed body size trends and nursery areas of O. megalodon by confining the previously used samples to upper anterior teeth offering more reliable TL estimates, and by taking paleolatitudes and sea-surface temperatures into consideration. We demonstrate that individuals of O. megalodon are on average larger in cooler water than those in warmer water – a pattern attributable to Bergmann’s rule showing a latitudinal body size gradient at least for the eastern Pacific late Miocene and the western Atlantic early Pliocene assemblages. While it is still possible that neonatal O. megalodon could have utilised nursery areas, the previously identified paleo-nursery areas based on body size may reflect temperature-dependent trends rather than the inferred reproductive strategy. Thus, the gigantism of O. megalodon in cooler waters was possibly further enhanced by its cooler environment. If so, the corollary of this study is that not all populations of O. megalodon likely grew to gigantic sizes equally, where the common notion that the species reached 18–20 m TL should be applied primarily to populations in cooler environments.",
    url = "https://doi.org/10.1080/08912963.2022.2032024",
    doi = "10.1080/08912963.2022.2032024",
    openalex = "W4220873179",
    references = "doi1010029781119174844, doi101016jpocean200904011, doi10103823231, doi101038346265a0, doi101038s4159802071387y, doi101046j13652699200300837x, doi1010800891296320191666840, doi1010800891296320201812598, doi101111evo13680, doi101126science1059412, doi101126scienceaba6853, doi101242jeb01556, doi101371journalpone0185185, doi1016410006356820010510633ticamo20co2, doi10166612117, doi107717peerj6088, openalexw3172537700"
}

Abstract One third of chondrichthyan species (sharks, rays, and chimeras) are threatened with extinction, mainly due to unsustainable fishing. Large accessible international markets for meat and luxury products like dried fins can help drive overfishing by encouraging targeted capture or retention of high‐value export species. If this is common, then species in international trade could have heightened extinction risk. Here, we examined the species composition of the Hong Kong shark fin market from 2014 to 2018, finding that traded species disproportionately occur in threatened categories (70.9%) and all premium value species are threatened. A small number of cosmopolitan species dominate the trade, but noncosmopolitan coastal species are still traded at concerning levels given their limited distribution. These coastal species are not generally subject to retention prohibitions, fisheries management, or international trade regulations and without management many could become extinct. The conservation potential of international trade regulations alone for coastal chondrichthyans depends on the extent to which overfishing is driven by export markets; socioeconomic studies of coastal fishing communities are needed to make this determination. Nonetheless, adding international trade regulations for more coastal shark species that are in the fin trade could prompt broad engagement with overfishing in nations lacking effective management.

@article{doi101111conl12910,
    author = "Cardeñosa, Diego and Shea, Stanley K. H. and Zhang, Huarong and Fischer, Gunter A. and Simpfendorfer, Colin A. and Chapman, Demian D.",
    title = "Two thirds of species in a global shark fin trade hub are threatened with extinction: Conservation potential of international trade regulations for coastal sharks",
    year = "2022",
    journal = "Conservation Letters",
    abstract = "Abstract One third of chondrichthyan species (sharks, rays, and chimeras) are threatened with extinction, mainly due to unsustainable fishing. Large accessible international markets for meat and luxury products like dried fins can help drive overfishing by encouraging targeted capture or retention of high‐value export species. If this is common, then species in international trade could have heightened extinction risk. Here, we examined the species composition of the Hong Kong shark fin market from 2014 to 2018, finding that traded species disproportionately occur in threatened categories (70.9\%) and all premium value species are threatened. A small number of cosmopolitan species dominate the trade, but noncosmopolitan coastal species are still traded at concerning levels given their limited distribution. These coastal species are not generally subject to retention prohibitions, fisheries management, or international trade regulations and without management many could become extinct. The conservation potential of international trade regulations alone for coastal chondrichthyans depends on the extent to which overfishing is driven by export markets; socioeconomic studies of coastal fishing communities are needed to make this determination. Nonetheless, adding international trade regulations for more coastal shark species that are in the fin trade could prompt broad engagement with overfishing in nations lacking effective management.",
    url = "https://doi.org/10.1111/conl.12910",
    doi = "10.1111/conl.12910",
    openalex = "W4285036182",
    references = "doi101016jcub202108062"
}

BACKGROUND: Animal-associated microbiomes can be influenced by both host and environmental factors. Comparing wild animals to those in zoos or aquariums can help disentangle the effects of host versus environmental factors, while also testing whether managed conditions foster a 'natural' host microbiome. Focusing on an endangered elasmobranch species-the whitespotted eagle ray Aetobatus narinari-we compared the skin, gill, and cloaca microbiomes of wild individuals to those at Georgia Aquarium. Whitespotted eagle ray microbiomes from Georgia Aquarium were also compared to those of cownose rays (Rhinoptera bonasus) in the same exhibit, allowing us to explore the effect of host identity on the ray microbiome. RESULTS: Long-term veterinary monitoring indicated that the rays in managed care did not have a history of disease and maintained health parameters consistent with those of wild individuals, with one exception. Aquarium whitespotted eagle rays were regularly treated to control parasite loads, but the effects on animal health were subclinical. Microbiome α- and β-diversity differed between wild versus aquarium whitespotted eagle rays at all body sites, with α-diversity significantly higher in wild individuals. β-diversity differences in wild versus aquarium whitespotted eagle rays were greater for skin and gill microbiomes compared to those of the cloaca. At each body site, we also detected microbial taxa shared between wild and aquarium eagle rays. Additionally, the cloaca, skin, and gill microbiomes of aquarium eagle rays differed from those of cownose rays in the same exhibit. Potentially pathogenic bacteria were at low abundance in all wild and aquarium rays. CONCLUSION: For whitespotted eagle rays, managed care was associated with a microbiome differing significantly from that of wild individuals. These differences were not absolute, as the microbiome of aquarium rays shared members with that of wild counterparts and was distinct from that of a cohabitating ray species. Eagle rays under managed care appear healthy, suggesting that their microbiomes are not associated with compromised host health. However, the ray microbiome is dynamic, differing with both environmental factors and host identity. Monitoring of aquarium ray microbiomes over time may identify taxonomic patterns that co-vary with host health.

@article{doi101186s42523022001878,
    author = "Clavere-Graciette, Ana G. and McWhirt, Mary E. and Hoopes, Lisa A. and Bassos‐Hull, Kim and Wilkinson, Krystan A. and Stewart, Frank J. and Pratte, Zoe A.",
    title = "Microbiome differences between wild and aquarium whitespotted eagle rays (Aetobatus narinari)",
    year = "2022",
    journal = "Animal Microbiome",
    abstract = "BACKGROUND: Animal-associated microbiomes can be influenced by both host and environmental factors. Comparing wild animals to those in zoos or aquariums can help disentangle the effects of host versus environmental factors, while also testing whether managed conditions foster a 'natural' host microbiome. Focusing on an endangered elasmobranch species-the whitespotted eagle ray Aetobatus narinari-we compared the skin, gill, and cloaca microbiomes of wild individuals to those at Georgia Aquarium. Whitespotted eagle ray microbiomes from Georgia Aquarium were also compared to those of cownose rays (Rhinoptera bonasus) in the same exhibit, allowing us to explore the effect of host identity on the ray microbiome. RESULTS: Long-term veterinary monitoring indicated that the rays in managed care did not have a history of disease and maintained health parameters consistent with those of wild individuals, with one exception. Aquarium whitespotted eagle rays were regularly treated to control parasite loads, but the effects on animal health were subclinical. Microbiome α- and β-diversity differed between wild versus aquarium whitespotted eagle rays at all body sites, with α-diversity significantly higher in wild individuals. β-diversity differences in wild versus aquarium whitespotted eagle rays were greater for skin and gill microbiomes compared to those of the cloaca. At each body site, we also detected microbial taxa shared between wild and aquarium eagle rays. Additionally, the cloaca, skin, and gill microbiomes of aquarium eagle rays differed from those of cownose rays in the same exhibit. Potentially pathogenic bacteria were at low abundance in all wild and aquarium rays. CONCLUSION: For whitespotted eagle rays, managed care was associated with a microbiome differing significantly from that of wild individuals. These differences were not absolute, as the microbiome of aquarium rays shared members with that of wild counterparts and was distinct from that of a cohabitating ray species. Eagle rays under managed care appear healthy, suggesting that their microbiomes are not associated with compromised host health. However, the ray microbiome is dynamic, differing with both environmental factors and host identity. Monitoring of aquarium ray microbiomes over time may identify taxonomic patterns that co-vary with host health.",
    url = "https://doi.org/10.1186/s42523-022-00187-8",
    doi = "10.1186/s42523-022-00187-8",
    openalex = "W4281385925",
    references = "doi101007s106410140294z"
}

PHYLOGENY AND ZOOGEOGRAPHY The Origin and Relationships of Early Chondrichthyes, Eileen D. Grogan and Richard Lund Historical Zoogeography of the Selachii, John A. Musick, Melanie M. Harbin, and Leonard.J.V. Compagno Phylogeny of Batoidea, John D. McEachran and Neil Aschliman Phylogeny and Classification of Extant Holocephali, Dominique A. Didier FORM, FUNCTION, AND PHYSIOLOGICAL PROCESSES Biomechanics of Locomotion in Sharks, Rays, and Chimeras, Cheryl A.D. Wilga and G. Lauder Prey Capture Behavior and Feeding Mechanics of Elasmobranchs, Philip J. Motta Metabolism, Energetic Demand, and Endothermy, John K. Carlson, Kenneth J. Goldman, and Christopher G. Lowe Food Consumption and Feeding Habits, Bradley M. Wetherbee and Enric Cortes Homeostasis: Osmoregulation, pH Regulation, and Nitrogen Excretion, David H. Evans, Peter M. Piermarini, and Keith P. Choe Reproductive Biology of Elasmobranchs, Jeffrey C. Carrier, Harold L. Pratt, Jr., and Jose I. Castro Hormonal Regulation of Elasmobranch Physiology, James Gelsleichter Sensory Biology of Elasmobranchs, Robert E. Hueter, David A. Mann, Karen P. Maruska, Joseph a. Sisneros, and Leo S. Demski The Immune System of Sharks, Skates, and Rays, Carl A. Luer, Catherine J. Walsh, and Ashby B. Bodine ECOLOGY AND LIFE HISTORY Age Determination and Validation in Chondrichthyan Fishes, Gregor M. Cailliet and Kenneth J. Goldman Life History Patterns, Demography, and Population Dynamics, Enric Cortes Genetics of Sharks, Skates, and Rays, Edward J. Heist Predator-Prey Interactions, Michael R. Heithaus Elasmobranchs as Hosts of Metazoan Parasites, Janine N. Caira and Claire J. Healy Assessing Habitat Use and Movement, Colin I. Simpfendorfer Michelle R. Heupel Subject Index Animal Index

@book{doi1012019781003262190,
    author = "Carrier, Jeffrey C. and Simpfendorfer, Colin A. and Heithaus, Michael R. and Yopak, Kara E.",
    title = "Biology of Sharks and Their Relatives",
    year = "2022",
    abstract = "PHYLOGENY AND ZOOGEOGRAPHY The Origin and Relationships of Early Chondrichthyes, Eileen D. Grogan and Richard Lund Historical Zoogeography of the Selachii, John A. Musick, Melanie M. Harbin, and Leonard.J.V. Compagno Phylogeny of Batoidea, John D. McEachran and Neil Aschliman Phylogeny and Classification of Extant Holocephali, Dominique A. Didier FORM, FUNCTION, AND PHYSIOLOGICAL PROCESSES Biomechanics of Locomotion in Sharks, Rays, and Chimeras, Cheryl A.D. Wilga and G. Lauder Prey Capture Behavior and Feeding Mechanics of Elasmobranchs, Philip J. Motta Metabolism, Energetic Demand, and Endothermy, John K. Carlson, Kenneth J. Goldman, and Christopher G. Lowe Food Consumption and Feeding Habits, Bradley M. Wetherbee and Enric Cortes Homeostasis: Osmoregulation, pH Regulation, and Nitrogen Excretion, David H. Evans, Peter M. Piermarini, and Keith P. Choe Reproductive Biology of Elasmobranchs, Jeffrey C. Carrier, Harold L. Pratt, Jr., and Jose I. Castro Hormonal Regulation of Elasmobranch Physiology, James Gelsleichter Sensory Biology of Elasmobranchs, Robert E. Hueter, David A. Mann, Karen P. Maruska, Joseph a. Sisneros, and Leo S. Demski The Immune System of Sharks, Skates, and Rays, Carl A. Luer, Catherine J. Walsh, and Ashby B. Bodine ECOLOGY AND LIFE HISTORY Age Determination and Validation in Chondrichthyan Fishes, Gregor M. Cailliet and Kenneth J. Goldman Life History Patterns, Demography, and Population Dynamics, Enric Cortes Genetics of Sharks, Skates, and Rays, Edward J. Heist Predator-Prey Interactions, Michael R. Heithaus Elasmobranchs as Hosts of Metazoan Parasites, Janine N. Caira and Claire J. Healy Assessing Habitat Use and Movement, Colin I. Simpfendorfer Michelle R. Heupel Subject Index Animal Index",
    url = "https://doi.org/10.1201/9781003262190",
    doi = "10.1201/9781003262190",
    openalex = "W1509118950"
}

Area-based conservation is essential to safeguard declining biodiversity. Several approaches have been developed for identifying networks of globally important areas based on the delineation of sites or seascapes of importance for various elements of biodiversity (e.g., birds, marine mammals). Sharks, rays, and chimaeras are facing a biodiversity crisis with an estimated 37% of species threatened with extinction driven by overfishing. Yet spatial planning tools often fail to consider the habitat needs critical for their survival. The Important Shark and Ray Area (ISRA) approach is proposed as a response to the dire global status of sharks, rays, and chimaeras. A set of four globally standardized scientific criteria, with seven sub-criteria, was developed based on input collated during four shark, biodiversity, and policy expert workshops conducted in 2022. The ISRA Criteria provide a framework to identify discrete, three-dimensional portions of habitat important for one or more shark, ray, or chimaera species, that have the potential to be delineated and managed for conservation. The ISRA Criteria can be applied to all environments where sharks occur (marine, estuarine, and freshwater) and consider the diversity of species, their complex behaviors and ecology, and biological needs. The identification of ISRAs will guide the development, design, and application of area-based conservation initiatives for sharks, rays, and chimaeras, and contribute to their recovery.

@article{doi103389fmars2022968853,
    author = "Hyde, Ciaran A. and di Sciara, Giuseppe Notarbartolo and Sorrentino, Lynn and Boyd, Charlotte and Finucci, Brittany and Fowler, Sarah and Kyne, Peter M. and Leurs, Guido and Simpfendorfer, Colin A. and Tetley, Michael J. and Womersley, Freya C. and Jabado, Rima W.",
    title = "Putting sharks on the map: A global standard for improving shark area-based conservation",
    year = "2022",
    journal = "Frontiers in Marine Science",
    abstract = "Area-based conservation is essential to safeguard declining biodiversity. Several approaches have been developed for identifying networks of globally important areas based on the delineation of sites or seascapes of importance for various elements of biodiversity (e.g., birds, marine mammals). Sharks, rays, and chimaeras are facing a biodiversity crisis with an estimated 37\% of species threatened with extinction driven by overfishing. Yet spatial planning tools often fail to consider the habitat needs critical for their survival. The Important Shark and Ray Area (ISRA) approach is proposed as a response to the dire global status of sharks, rays, and chimaeras. A set of four globally standardized scientific criteria, with seven sub-criteria, was developed based on input collated during four shark, biodiversity, and policy expert workshops conducted in 2022. The ISRA Criteria provide a framework to identify discrete, three-dimensional portions of habitat important for one or more shark, ray, or chimaera species, that have the potential to be delineated and managed for conservation. The ISRA Criteria can be applied to all environments where sharks occur (marine, estuarine, and freshwater) and consider the diversity of species, their complex behaviors and ecology, and biological needs. The identification of ISRAs will guide the development, design, and application of area-based conservation initiatives for sharks, rays, and chimaeras, and contribute to their recovery.",
    url = "https://doi.org/10.3389/fmars.2022.968853",
    doi = "10.3389/fmars.2022.968853",
    openalex = "W4295412873",
    references = "doi101016jcub202108062"
}

Elasmobranchii are relatively well-studied. However, numerous phylogenetic uncertainties about their relationships remain. Here, we revisit the phylogenetic evidence based on a detailed morphological re-evaluation of all the major extant batomorph clades (skates and rays), including several holomorphic fossil taxa from the Palaeozoic, Mesozoic and Cenozoic, and an extensive outgroup sampling, which includes sharks, chimaeras and several other fossil chondrichthyans. The parsimony and maximum-likelihood analyses found more resolved but contrasting topologies, with the Bayesian inference tree neither supporting nor disfavouring any of them. Overall, the analyses result in similar clade compositions and topologies, with the Jurassic batomorphs forming the sister clade to all the other batomorphs, whilst all the Cretaceous batomorphs are nested within the remaining main clades. The disparate arrangements recovered under the different criteria suggest that a detailed study of Jurassic taxa is of utmost importance to present a more consistent topology in the deeper nodes, as issues continue to be present when analysing those clades previously recognized only by molecular analyses (e.g., Rhinopristiformes and Torpediniformes). The consistent placement of fossil taxa within specific groups by the different phylogenetic criteria is promising and indicates that the inclusion of more fossil taxa in the present matrix will likely not cause loss of resolution, therefore suggesting that a strong phylogenetic signal can be recovered from fossil taxa.

@article{doi103390d14060456,
    author = "Villalobos‐Segura, Eduardo and Marramà, Giuseppe and Carnevale, Giorgio and Claeson, Kerin M. and Underwood, Charlie J. and Naylor, Gavin J. P. and Kriwet, Jürgen",
    title = "The Phylogeny of Rays and Skates (Chondrichthyes: Elasmobranchii) Based on Morphological Characters Revisited",
    year = "2022",
    journal = "Diversity",
    abstract = "Elasmobranchii are relatively well-studied. However, numerous phylogenetic uncertainties about their relationships remain. Here, we revisit the phylogenetic evidence based on a detailed morphological re-evaluation of all the major extant batomorph clades (skates and rays), including several holomorphic fossil taxa from the Palaeozoic, Mesozoic and Cenozoic, and an extensive outgroup sampling, which includes sharks, chimaeras and several other fossil chondrichthyans. The parsimony and maximum-likelihood analyses found more resolved but contrasting topologies, with the Bayesian inference tree neither supporting nor disfavouring any of them. Overall, the analyses result in similar clade compositions and topologies, with the Jurassic batomorphs forming the sister clade to all the other batomorphs, whilst all the Cretaceous batomorphs are nested within the remaining main clades. The disparate arrangements recovered under the different criteria suggest that a detailed study of Jurassic taxa is of utmost importance to present a more consistent topology in the deeper nodes, as issues continue to be present when analysing those clades previously recognized only by molecular analyses (e.g., Rhinopristiformes and Torpediniformes). The consistent placement of fossil taxa within specific groups by the different phylogenetic criteria is promising and indicates that the inclusion of more fossil taxa in the present matrix will likely not cause loss of resolution, therefore suggesting that a strong phylogenetic signal can be recovered from fossil taxa.",
    url = "https://doi.org/10.3390/d14060456",
    doi = "10.3390/d14060456",
    openalex = "W4281702573",
    references = "doi101038nature20806, doi101111j10958649201203245x, doi101111j146363951940tb00339x"
}

Overfishing, habitat loss, and climate change are driving population declines in many species. Understanding a species' capacity to recover from these and other threats is necessary for prioritising management. The maximum intrinsic rate of population increase (rmax) can be used to compare which species or groups are particularly sensitive to ongoing threats. To investigate global patterns of intrinsic sensitivity of rays and skates (superorder Batoidea), we calculated rmax of 85 species using a modified Euler-Lotka model that accounts for survival to maturity. We examined how rmax varies with body mass, temperature, and depth using an information-theoretic approach through model selection, accounting for phylogenetic non-independence. Although we observed an overall positive relationship between rmax and temperature, we found that warm, shallow-water rays were more intrinsically sensitive to exploitation (lower rmax) than cold, deep-water skates (higher rmax). We hypothesise that this pattern is likely driven by their different reproductive strategies as live-bearing rays have fewer offspring compared to egg-laying skates, and caution that future research should focus on understanding differences in the mortality schedule of juveniles and sub-adults to understand if survival to maturity is comparable. Our findings highlight the high vulnerability of warm, shallow-water ray species to overexploitation and other threats due to their intrinsically low maximum population growth rates. These differences in rmax have conservation implications for our understanding of the geographic patterns in extinction risk, suggesting that tropical rays are more intrinsically sensitive.

@article{doi101016jbiocon2023110003,
    author = "Barrowclift, Ellen and Gravel, Sarah and Pardo, Sebastián A. and Bigman, Jennifer S. and Berggren, Per and Dulvy, Nicholas K.",
    title = "Tropical rays are intrinsically more sensitive to overfishing than the temperate skates",
    year = "2023",
    journal = "Biological Conservation",
    abstract = "Overfishing, habitat loss, and climate change are driving population declines in many species. Understanding a species' capacity to recover from these and other threats is necessary for prioritising management. The maximum intrinsic rate of population increase (rmax) can be used to compare which species or groups are particularly sensitive to ongoing threats. To investigate global patterns of intrinsic sensitivity of rays and skates (superorder Batoidea), we calculated rmax of 85 species using a modified Euler-Lotka model that accounts for survival to maturity. We examined how rmax varies with body mass, temperature, and depth using an information-theoretic approach through model selection, accounting for phylogenetic non-independence. Although we observed an overall positive relationship between rmax and temperature, we found that warm, shallow-water rays were more intrinsically sensitive to exploitation (lower rmax) than cold, deep-water skates (higher rmax). We hypothesise that this pattern is likely driven by their different reproductive strategies as live-bearing rays have fewer offspring compared to egg-laying skates, and caution that future research should focus on understanding differences in the mortality schedule of juveniles and sub-adults to understand if survival to maturity is comparable. Our findings highlight the high vulnerability of warm, shallow-water ray species to overexploitation and other threats due to their intrinsically low maximum population growth rates. These differences in rmax have conservation implications for our understanding of the geographic patterns in extinction risk, suggesting that tropical rays are more intrinsically sensitive.",
    url = "https://doi.org/10.1016/j.biocon.2023.110003",
    doi = "10.1016/j.biocon.2023.110003",
    openalex = "W4361294259",
    references = "doi1012019781439856000"
}

Sharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwide. Here, we show that nearly two-thirds (59%) of the 134 coral-reef associated shark and ray species are threatened with extinction. Alongside marine mammals, sharks and rays are among the most threatened groups found on coral reefs. Overfishing is the main cause of elevated extinction risk, compounded by climate change and habitat degradation. Risk is greatest for species that are larger-bodied (less resilient and higher trophic level), widely distributed across several national jurisdictions (subject to a patchwork of management), and in nations with greater fishing pressure and weaker governance. Population declines have occurred over more than half a century, with greatest declines prior to 2005. Immediate action through local protections, combined with broad-scale fisheries management and Marine Protected Areas, is required to avoid extinctions and the loss of critical ecosystem function condemning reefs to a loss of shark and ray biodiversity and ecosystem services, limiting livelihoods and food security.

@article{doi101038s4146702235091x,
    author = "Sherman, C. Samantha and Simpfendorfer, Colin A. and Pacoureau, Nathan and Matsushiba, Jay H. and Yan, Helen F. and Walls, Rachel H.L. and Rigby, Cassandra L. and VanderWright, Wade J. and Jabado, Rima W. and Pollom, Riley A. and Carlson, John K. and Charvet, Patrícia and Ali, Ahmad and Fahmi, Fahmi and Cheok, Jessica and Derrick, Danielle H. and Herman, Katelyn B. and Finucci, Brittany and Eddy, Tyler D. and Palomares, Maria Lourdes D. and Avalos-Castillo, Christopher G. and Kinattumkara, Bineesh and del Pilar Blanco‐Parra, María and Dharmadi and Espinoza, Mario and Fernando, Daniel and Haque, Alifa B. and Mejía‐Falla, Paola A. and Navia, Andrés F. and Pérez‐Jiménez, Juan Carlos and Utzurrum, Jean and Yuneni, Ranny R. and Dulvy, Nicholas K.",
    title = "Half a century of rising extinction risk of coral reef sharks and rays",
    year = "2023",
    journal = "Nature Communications",
    abstract = "Sharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwide. Here, we show that nearly two-thirds (59\%) of the 134 coral-reef associated shark and ray species are threatened with extinction. Alongside marine mammals, sharks and rays are among the most threatened groups found on coral reefs. Overfishing is the main cause of elevated extinction risk, compounded by climate change and habitat degradation. Risk is greatest for species that are larger-bodied (less resilient and higher trophic level), widely distributed across several national jurisdictions (subject to a patchwork of management), and in nations with greater fishing pressure and weaker governance. Population declines have occurred over more than half a century, with greatest declines prior to 2005. Immediate action through local protections, combined with broad-scale fisheries management and Marine Protected Areas, is required to avoid extinctions and the loss of critical ecosystem function condemning reefs to a loss of shark and ray biodiversity and ecosystem services, limiting livelihoods and food security.",
    url = "https://doi.org/10.1038/s41467-022-35091-x",
    doi = "10.1038/s41467-022-35091-x",
    openalex = "W4317034991",
    references = "doi101016jcub202108062"
}

Elasmobranchs (sharks, rays and skates) are among the most threatened marine vertebrates, yet their global functional diversity remains largely unknown. Here, we use a trait dataset of >1000 species to assess elasmobranch functional diversity and compare it against other previously studied biodiversity facets (taxonomic and phylogenetic), to identify species- and spatial- conservation priorities. We show that threatened species encompass the full extent of functional space and disproportionately include functionally distinct species. Applying the conservation metric FUSE (Functionally Unique, Specialised, and Endangered) reveals that most top-ranking species differ from the top Evolutionarily Distinct and Globally Endangered (EDGE) list. Spatial analyses further show that elasmobranch functional richness is concentrated along continental shelves and around oceanic islands, with 18 distinguishable hotspots. These hotspots only marginally overlap with those of other biodiversity facets, reflecting a distinct spatial fingerprint of functional diversity. Elasmobranch biodiversity facets converge with fishing pressure along the coast of China, which emerges as a critical frontier in conservation. Meanwhile, several components of elasmobranch functional diversity fall in high seas and/or outside the global network of marine protected areas. Overall, our results highlight acute vulnerability of the world's elasmobranchs' functional diversity and reveal global priorities for elasmobranch functional biodiversity previously overlooked.

@article{doi101038s41467023432123,
    author = "Pimiento, Catalina and Albouy, Camille and Silvestro, Daniele and Mouton, Théophile L. and Velez, Laure and Mouillot, David and Judah, Aaron B. and Griffin, John N. and Leprieur, Fabien",
    title = "Functional diversity of sharks and rays is highly vulnerable and supported by unique species and locations worldwide",
    year = "2023",
    journal = "Nature Communications",
    abstract = "Elasmobranchs (sharks, rays and skates) are among the most threatened marine vertebrates, yet their global functional diversity remains largely unknown. Here, we use a trait dataset of >1000 species to assess elasmobranch functional diversity and compare it against other previously studied biodiversity facets (taxonomic and phylogenetic), to identify species- and spatial- conservation priorities. We show that threatened species encompass the full extent of functional space and disproportionately include functionally distinct species. Applying the conservation metric FUSE (Functionally Unique, Specialised, and Endangered) reveals that most top-ranking species differ from the top Evolutionarily Distinct and Globally Endangered (EDGE) list. Spatial analyses further show that elasmobranch functional richness is concentrated along continental shelves and around oceanic islands, with 18 distinguishable hotspots. These hotspots only marginally overlap with those of other biodiversity facets, reflecting a distinct spatial fingerprint of functional diversity. Elasmobranch biodiversity facets converge with fishing pressure along the coast of China, which emerges as a critical frontier in conservation. Meanwhile, several components of elasmobranch functional diversity fall in high seas and/or outside the global network of marine protected areas. Overall, our results highlight acute vulnerability of the world's elasmobranchs' functional diversity and reveal global priorities for elasmobranch functional biodiversity previously overlooked.",
    url = "https://doi.org/10.1038/s41467-023-43212-3",
    doi = "10.1038/s41467-023-43212-3",
    openalex = "W4388973119",
    references = "doi101073pnas1902693116, doi101111brv12203"
}

Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheries management success for 11 coastal sharks in US waters by comparing population trends through a Bayesian state-space model before and after the implementation of the 1993 Fisheries Management Plan for Sharks. We took advantage of the spatial and temporal gradients in fishing exposure and fisheries management in the Western Atlantic to analyze the effect on the Red List status of all 26 wide-ranging coastal sharks and rays. We show that extinction risk was greater where fishing pressure was higher, but this was offset by the strength of management engagement (indicated by strength of National and Regional Plan of Action for sharks and rays). The regional Red List Index (which tracks changes in extinction risk through time) declined in all regions until the 1980s but then improved in the North and Central Atlantic such that the average extinction risk is currently half that in the Southwest. Many sharks and rays are wide ranging, and successful fisheries management in one country can be undone by poorly regulated or unregulated fishing elsewhere. Our study underscores that well-enforced, science-based management of carefully monitored fisheries can achieve conservation success, even for slow-growing species.

@article{doi101073pnas2216891120,
    author = "Pacoureau, Nathan and Carlson, John K. and Kindsvater, Holly K. and Rigby, Cassandra L. and Winker, Henning and Simpfendorfer, Colin A. and Charvet, Patrícia and Pollom, Riley A. and Barreto, Rodrigo and Sherman, C. Samantha and Talwar, Brendan S. and Skerritt, Daniel J. and Sumaila, U. Rashid and Matsushiba, Jay H. and VanderWright, Wade J. and Yan, Helen F. and Dulvy, Nicholas K.",
    title = "Conservation successes and challenges for wide-ranging sharks and rays",
    year = "2023",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheries management success for 11 coastal sharks in US waters by comparing population trends through a Bayesian state-space model before and after the implementation of the 1993 Fisheries Management Plan for Sharks. We took advantage of the spatial and temporal gradients in fishing exposure and fisheries management in the Western Atlantic to analyze the effect on the Red List status of all 26 wide-ranging coastal sharks and rays. We show that extinction risk was greater where fishing pressure was higher, but this was offset by the strength of management engagement (indicated by strength of National and Regional Plan of Action for sharks and rays). The regional Red List Index (which tracks changes in extinction risk through time) declined in all regions until the 1980s but then improved in the North and Central Atlantic such that the average extinction risk is currently half that in the Southwest. Many sharks and rays are wide ranging, and successful fisheries management in one country can be undone by poorly regulated or unregulated fishing elsewhere. Our study underscores that well-enforced, science-based management of carefully monitored fisheries can achieve conservation success, even for slow-growing species.",
    url = "https://doi.org/10.1073/pnas.2216891120",
    doi = "10.1073/pnas.2216891120",
    openalex = "W4317797522",
    references = "doi101016jcub202108062"
}

), that remotely documented the location and timing of birth by a highly migratory oceanic animal in the wild. This novel technology will be especially valuable for the protection of threatened and endangered shark species, where protection of pupping and nursery grounds is a conservation priority.

@article{doi101126sciadvadd6340,
    author = "Sulikowski, James A. and Hammerschlag, Neil",
    title = "A novel intrauterine satellite transmitter to identify parturition in large sharks",
    year = "2023",
    journal = "Science Advances",
    abstract = "), that remotely documented the location and timing of birth by a highly migratory oceanic animal in the wild. This novel technology will be especially valuable for the protection of threatened and endangered shark species, where protection of pupping and nursery grounds is a conservation priority.",
    url = "https://doi.org/10.1126/sciadv.add6340",
    doi = "10.1126/sciadv.add6340",
    openalex = "W4322754467",
    references = "doi101007s11160020096040, wheeler2020anthropogenic"
}

The Cretaceous-Paleogene event was the last mass extinction event, yet its impact and long-term effects on species-level marine vertebrate diversity remain largely uncharacterized. We quantified elasmobranch (sharks, skates, and rays) speciation, extinction, and ecological change resulting from the end-Cretaceous event using >3200 fossil occurrences and 675 species spanning the Late Cretaceous-Paleocene interval at global scale. Elasmobranchs declined by >62% at the Cretaceous-Paleogene boundary and did not fully recover in the Paleocene. The end-Cretaceous event triggered a heterogeneous pattern of extinction, with rays and durophagous species reaching the highest levels of extinction (>72%) and sharks and nondurophagous species being less affected. Taxa with large geographic ranges and/or those restricted to high-latitude settings show higher survival. The Cretaceous-Paleogene event drastically altered the evolutionary history of marine ecosystems.

@article{doi101126scienceabn2080,
    author = "Guinot, Guillaume and Condamine, Fabien L.",
    title = "Global impact and selectivity of the Cretaceous-Paleogene mass extinction among sharks, skates, and rays",
    year = "2023",
    journal = "Science",
    abstract = "The Cretaceous-Paleogene event was the last mass extinction event, yet its impact and long-term effects on species-level marine vertebrate diversity remain largely uncharacterized. We quantified elasmobranch (sharks, skates, and rays) speciation, extinction, and ecological change resulting from the end-Cretaceous event using >3200 fossil occurrences and 675 species spanning the Late Cretaceous-Paleocene interval at global scale. Elasmobranchs declined by >62\% at the Cretaceous-Paleogene boundary and did not fully recover in the Paleocene. The end-Cretaceous event triggered a heterogeneous pattern of extinction, with rays and durophagous species reaching the highest levels of extinction (>72\%) and sharks and nondurophagous species being less affected. Taxa with large geographic ranges and/or those restricted to high-latitude settings show higher survival. The Cretaceous-Paleogene event drastically altered the evolutionary history of marine ecosystems.",
    url = "https://doi.org/10.1126/science.abn2080",
    doi = "10.1126/science.abn2080",
    openalex = "W4321749010",
    references = "doi101002jmor1073, doi101038s41467021237540, doi101073pnas1902693116, doi1010800891296320201812598, doi101111brv12203, doi101111evo13680, doi101111j10958649201203245x"
}

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities.

@article{doi101126scienceade4884,
    author = "Simpfendorfer, Colin A. and Heithaus, Michael R. and Heupel, Michelle R. and MacNeil, M. Aaron and Meekan, Mark G. and Harvey, Euan S. and Sherman, C. Samantha and Currey‐Randall, Leanne M. and Goetze, Jordan S. and Kiszka, Jérémy J. and Rees, Matthew J. and Speed, Conrad W. and Udyawer, Vinay and Bond, Mark E. and Flowers, Kathryn I. and Clementi, Gina M. and Valentin-Albanese, Jasmine and Adam, M. Shiham and Ali, Khadeeja and Asher, Jacob and Aylagas, Eva and Beaufort, Océane and Benjamin, Cecilie and Bernard, Anthony T.F. and Berumen, Michael L. and Bierwagen, Stacy L. and Birrell, Chico and Bonnema, Erika and Bown, Rosalind M. K. and Brooks, Edward J. and Brown, Judith and Buddo, Dayne and Burke, Patrick J. and Cáceres, Camila and Cambra, Marta and Cardeñosa, Diego and Carrier, Jeffrey C. and Casareto, Sara and Caselle, Jennifer E. and Charloo, Venkatesh and Cinner, Joshua E. and Claverie, Thomas and Clua, Éric and Cochran, Jesse E. M. and Cook, Neil D. and Cramp, Jessica E. and D’Alberto, Brooke M. and de Graaf, Martin and Dornhege, Mareike and Espinoza, Mario and Estep, Andy and Fanovich, Lanya and Farabaugh, Naomi F. and Fernando, Daniel and Ferreira, Carlos Eduardo Leite and Fields, Candace Y. A. and Flam, Anna L. and Floros, Camilla and Fourqurean, Virginia and Gajdzik, Laura and Barcia, Laura García and Garla, Ricardo Clapis and Gastrich, Kirk and George, Lachlan and Giarrizzo, Tommaso and Graham, Rory and Guttridge, Tristan L. and Hagan, Valerie and Hardenstine, Royale S. and Heck, Stephen M. and Henderson, Aaron C. and Heithaus, Patricia and Hertler, Heidi and Hoyos‐Padilla, Mauricio and Hueter, Robert E. and Jabado, Rima W. and Joyeux, Jean‐Christophe and Jaiteh, Vanessa and Johnson, Mohini and Jupiter, Stacy D. and Kaimuddin, Muslimin and Kasana, Devanshi and Kelley, Megan and Kessel, Steven T. and Kiilu, Benedict and Kirata, Taratau and Kuguru, Baraka and Kyne, Fabian and Langlois, Tim and Lara-Lizardi, Frida and Lawe, Jaedon and Lédée, Elodie J. I. and Lindfield, Steven J. and Luna‐Acosta, Andrea and Maggs, JQ and Manjaji‐Matsumoto, B. Mabel and Marshall, Andrea D. and Martin, L. D. and Mateos‐Molina, Daniel and Matich, Philip",
    title = "Widespread diversity deficits of coral reef sharks and rays",
    year = "2023",
    journal = "Science",
    abstract = "A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73\% for five common resident reef shark species and that individual shark species were not detected at 34 to 47\% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities.",
    url = "https://doi.org/10.1126/science.ade4884",
    doi = "10.1126/science.ade4884",
    openalex = "W4380763169",
    references = "doi101016jcub202108062"
}

Abstract The chondrichthyan lineage diverged from the osteichthyan line around 440 million years ago, resulting in a vast evolutionary gulf between modern elasmobranchs and other vertebrates. Though this has supported the assumption that as an ancient line, elasmobranchs are dangerously stupid, intelligent actions including social interactions have been noted in the field, while laboratory studies have confirmed a variety of cognitive capacities. Yet, due to fear of sharks and the difficulties of observing them in their aquatic environments, few ethological studies have been done, so their natural behaviour remains little known. On noting that the blacktip reef shark, Carcharhinus melanopterus, displayed complex actions during incidental meetings, a long-term ethological study of the species was carried out on the north shore of Mo’orea Island, French Polynesia. During the 6.5 years of the study, new behaviours continued to present. The 35 context-specific actions identified as comprising the behavioural repertoire of C. melanopterus are described.

@article{doi1011631568539xbja10213,
    author = "Porcher, Ila France",
    title = "Ethogram for blacktip reef sharks (Carcharhinus melanopterus)",
    year = "2023",
    journal = "Behaviour",
    abstract = "Abstract The chondrichthyan lineage diverged from the osteichthyan line around 440 million years ago, resulting in a vast evolutionary gulf between modern elasmobranchs and other vertebrates. Though this has supported the assumption that as an ancient line, elasmobranchs are dangerously stupid, intelligent actions including social interactions have been noted in the field, while laboratory studies have confirmed a variety of cognitive capacities. Yet, due to fear of sharks and the difficulties of observing them in their aquatic environments, few ethological studies have been done, so their natural behaviour remains little known. On noting that the blacktip reef shark, Carcharhinus melanopterus, displayed complex actions during incidental meetings, a long-term ethological study of the species was carried out on the north shore of Mo’orea Island, French Polynesia. During the 6.5 years of the study, new behaviours continued to present. The 35 context-specific actions identified as comprising the behavioural repertoire of C. melanopterus are described.",
    url = "https://doi.org/10.1163/1568539x-bja10213",
    doi = "10.1163/1568539x-bja10213",
    openalex = "W4367369395",
    references = "doi1011631568539xbja10214"
}

Abstract In this review of the behavioural patterns of chondrichthyan fishes, we have strived to produce a comprehensive catalogue of events and states and develop standardized terminology. Hence, actions that are slightly different, will be pooled under inclusive titles. Those used by different investigators are included in quotations within the textual descriptions of the motor patterns. This standardized ethogram will ideally lead to an increase in inter-observer reliability, giving researchers more confidence when reading colleagues’ papers that report behaviours that appear similar to theirs despite being described for different species. The descriptions are presented under the following categories: (1) maintenance (2) courtship (3) filter feeding (4) scavenging (5) predation (6) sociality (7) aggression and (8) defence. The many actions are illustrated by line drawings and photographs in composite figures with an attempt to provide an example of each action for a chimaera, shark, and ray. The diversity of patterns is evident from this ethogram, consistent with observation that the brain-to-body mass ratios of cartilaginous fishes are greater than a third of the bird species and greater than those for some mammalian species. The major impetus for assembling this ethogram is to demonstrate the diversity of behaviours exhibited by members of the Chondrichthyes and to dispel the apocryphal belief that members of this taxon are ‘simple feeding machines’.

@article{doi1011631568539xbja10214,
    author = "Klimley, A. Peter and Porcher, Ila France and Clua, Éric and Pratt, Harold L.",
    title = "A review of the behaviours of the Chondrichthyes: a multi-species ethogram for the chimaeras, sharks, and rays",
    year = "2023",
    journal = "Behaviour",
    abstract = "Abstract In this review of the behavioural patterns of chondrichthyan fishes, we have strived to produce a comprehensive catalogue of events and states and develop standardized terminology. Hence, actions that are slightly different, will be pooled under inclusive titles. Those used by different investigators are included in quotations within the textual descriptions of the motor patterns. This standardized ethogram will ideally lead to an increase in inter-observer reliability, giving researchers more confidence when reading colleagues’ papers that report behaviours that appear similar to theirs despite being described for different species. The descriptions are presented under the following categories: (1) maintenance (2) courtship (3) filter feeding (4) scavenging (5) predation (6) sociality (7) aggression and (8) defence. The many actions are illustrated by line drawings and photographs in composite figures with an attempt to provide an example of each action for a chimaera, shark, and ray. The diversity of patterns is evident from this ethogram, consistent with observation that the brain-to-body mass ratios of cartilaginous fishes are greater than a third of the bird species and greater than those for some mammalian species. The major impetus for assembling this ethogram is to demonstrate the diversity of behaviours exhibited by members of the Chondrichthyes and to dispel the apocryphal belief that members of this taxon are ‘simple feeding machines’.",
    url = "https://doi.org/10.1163/1568539x-bja10214",
    doi = "10.1163/1568539x-bja10214",
    openalex = "W4366481754",
    references = "doi101007bf00346421, doi1010160376635787900210, doi101016janbehav201111008, doi101023a1007656126281, doi101093ae452126, doi101163156853981x00220, doi1023072412482, doi105860choice421559, doi105962bhltitle3596, openalexw596245786"
}

This study describes the first potential multi-species shark nursery area in Atlantic Africa (Sal Rei Bay – SRB, Boa Vista Island, Cabo Verde). From August 2016 to September 2019, 6162 neonates and juveniles of 5 different shark species were observed in SRB using beach gillnet-based bycatch surveys, namely milk (Rhizoprionodon acutus; n= 4908), scalloped hammerhead (Sphyrna lewini; n= 1035), blacktip (Carcharhinus limbatus; n=115), Atlantic weasel (Paragaleus pectoralis; n= 93) and nurse (Ginglymostoma cirratum; n= 12) sharks. Except for nurse sharks, significant seasonal variations in shark relative abundance were observed, with higher levels being recorded during summer and autumn. These findings, together with local knowledge (interviews to fishermen), denote the consistent use of SRB by juvenile sharks and its preference relative to other areas in the region. Ensuring the protection and conservation of SRB nursery area is especially relevant as, according to IUCN, all identified shark species are threatened with extinction over the near-future – in particular, scalloped hammerheads (critically endangered) and Atlantic weasel sharks (endangered). The effective protection of SRB will not only support the conservation of shark populations, but also of other charismatic fauna (e.g., loggerhead turtles) and broader benthic and pelagic ecosystems.

@article{doi103389fmars20231077748,
    author = "Rosa, Rui and Nunes, Emanuel and Pissarra, Vasco and Santos, Catarina Pereira and Varela, Jaquelino and Baptista, Miguel and Castro, Joana and Paula, José Ricardo and Repolho, Tiago and Marques, Tiago A. and Freitas, Rui and Santos, Catarina Frazão",
    title = "Evidence for the first multi-species shark nursery area in Atlantic Africa (Boa Vista Island, Cabo Verde)",
    year = "2023",
    journal = "Frontiers in Marine Science",
    abstract = "This study describes the first potential multi-species shark nursery area in Atlantic Africa (Sal Rei Bay – SRB, Boa Vista Island, Cabo Verde). From August 2016 to September 2019, 6162 neonates and juveniles of 5 different shark species were observed in SRB using beach gillnet-based bycatch surveys, namely milk (Rhizoprionodon acutus; n= 4908), scalloped hammerhead (Sphyrna lewini; n= 1035), blacktip (Carcharhinus limbatus; n=115), Atlantic weasel (Paragaleus pectoralis; n= 93) and nurse (Ginglymostoma cirratum; n= 12) sharks. Except for nurse sharks, significant seasonal variations in shark relative abundance were observed, with higher levels being recorded during summer and autumn. These findings, together with local knowledge (interviews to fishermen), denote the consistent use of SRB by juvenile sharks and its preference relative to other areas in the region. Ensuring the protection and conservation of SRB nursery area is especially relevant as, according to IUCN, all identified shark species are threatened with extinction over the near-future – in particular, scalloped hammerheads (critically endangered) and Atlantic weasel sharks (endangered). The effective protection of SRB will not only support the conservation of shark populations, but also of other charismatic fauna (e.g., loggerhead turtles) and broader benthic and pelagic ecosystems.",
    url = "https://doi.org/10.3389/fmars.2023.1077748",
    doi = "10.3389/fmars.2023.1077748",
    openalex = "W4318833228",
    references = "doi101007s11160020096040, wheeler2020anthropogenic"
}

, as similarly described for the species in the Western North Atlantic off the U.S. coast. From June to November, the seawater temperature oscillated between 19 and 24 °C, and massive aggregations of females occurred at 22-24 °C and in a few specific sandy beaches on the islands. Spiny butterfly rays, mostly females, show a preference for aggregating in shallow waters during summertime, probably conditionate to mating or breeding behaviour.

@article{doi103390ani13091455,
    author = "Espino‐Ruano, Ana and Castro, J.J. and Guerra‐Marrero, Airam and Couce‐Montero, Lorena and Meyers, Eva and Santana, Ángelo and Jiménez‐Alvarado, David",
    title = "Aggregative Behaviour of Spiny Butterfly Rays (Gymnura altavela, Linnaeus, 1758) in the Shallow Coastal Zones of Gran Canaria in the Eastern Central Atlantic",
    year = "2023",
    journal = "Animals",
    abstract = ", as similarly described for the species in the Western North Atlantic off the U.S. coast. From June to November, the seawater temperature oscillated between 19 and 24 °C, and massive aggregations of females occurred at 22-24 °C and in a few specific sandy beaches on the islands. Spiny butterfly rays, mostly females, show a preference for aggregating in shallow waters during summertime, probably conditionate to mating or breeding behaviour.",
    url = "https://doi.org/10.3390/ani13091455",
    doi = "10.3390/ani13091455",
    openalex = "W4366986966",
    references = "doi101007s106410140294z"
}

The elasmobranch fishes, both the sharks and rays, which inhabit the underwater environment, display breaching behaviors consisting of their sudden propulsion out of the water and into the air. They then land on top of the sea surface, displacing water upon contact. At other times, they do not completely clear the water, but partly so, performing a lunge rather than a clear jump or breach. These behaviors have been reported in the scientific literature for the fast-swimming predatory sharks, but also for a slow-swimming planktivorous shark as well as many of the rays. We identify breaching behavior in species in the selachan families, Alopiidae, Carcharhinidae, Cetorhinidae and Lamnidae, and batoidan families, Mobulidae, Aetobatidae, Myliobatidae, Rhinopteridae, and Dasyatidae. We present and discuss evidence in support of the following functions: (1) parasite removal, (2) clearing of gill rakers, (3) expulsion of feces or internal parasites, (4) courtship, (5) attraction of conspecifics, (6) repelled by conspecifics and interpecifics, (7) evasion by conspecifics, (8) feeding, (9) concentrating or stunning of prey, and (10) birthing. Our recording of this behavior has evolved beyond simple observations and now incorporates information gathered through advanced technologies, such as animal-borne data loggers, digital photography, and observations from aerial or underwater drones. Within this context, we review the relevant literature, describing studies and research to provide additional insight into the causation of these behaviors.

@article{doi101007s10641024015845,
    author = "Klimley, A. Peter and Curtis, Tobey H. and Johnston, Emmett M. and Kock, Alison and Stevens, Guy M. W.",
    title = "A review of elasmobranch breaching behavior: why do sharks and rays propel themselves out of the water into the air?",
    year = "2024",
    journal = "Environmental Biology of Fishes",
    abstract = "The elasmobranch fishes, both the sharks and rays, which inhabit the underwater environment, display breaching behaviors consisting of their sudden propulsion out of the water and into the air. They then land on top of the sea surface, displacing water upon contact. At other times, they do not completely clear the water, but partly so, performing a lunge rather than a clear jump or breach. These behaviors have been reported in the scientific literature for the fast-swimming predatory sharks, but also for a slow-swimming planktivorous shark as well as many of the rays. We identify breaching behavior in species in the selachan families, Alopiidae, Carcharhinidae, Cetorhinidae and Lamnidae, and batoidan families, Mobulidae, Aetobatidae, Myliobatidae, Rhinopteridae, and Dasyatidae. We present and discuss evidence in support of the following functions: (1) parasite removal, (2) clearing of gill rakers, (3) expulsion of feces or internal parasites, (4) courtship, (5) attraction of conspecifics, (6) repelled by conspecifics and interpecifics, (7) evasion by conspecifics, (8) feeding, (9) concentrating or stunning of prey, and (10) birthing. Our recording of this behavior has evolved beyond simple observations and now incorporates information gathered through advanced technologies, such as animal-borne data loggers, digital photography, and observations from aerial or underwater drones. Within this context, we review the relevant literature, describing studies and research to provide additional insight into the causation of these behaviors.",
    url = "https://doi.org/10.1007/s10641-024-01584-5",
    doi = "10.1007/s10641-024-01584-5",
    openalex = "W4401957855",
    references = "doi1011631568539xbja10214"
}

The emergence and subsequent evolution of pectoral fins is a key point in vertebrate evolution, as pectoral fins are dominant control surfaces for locomotion in extant fishes. 1, 2, 3 However, major gaps remain in our understanding of the diversity and evolution of pectoral fins among cartilaginous fishes (Chondrichthyes), a group with an evolutionary history spanning over 400 million years with current selachians (modern sharks) appearing about 200 million years ago. 4, 5, 6 Modern sharks are a charismatic group of vertebrates often thought to be predators roaming the open ocean and coastal areas, but most extant species occupy the seafloor. 4 Here we use an integrative approach to understand what facilitated the expansion to the pelagic realm and what morphological changes accompanied this shift. On the basis of comparative analyses in the framework of a time-calibrated molecular phylogeny, 7 we show that modern sharks expanded to the pelagic realm no later than the Early Cretaceous (Barremian). The pattern of pectoral fin aspect ratios across selachians is congruent with adaptive evolution, and we identify an increase of the subclade disparity of aspect ratio at a time when sea surface temperatures were at their highest. 8 The expansion to open ocean habitats likely involved extended bouts of sustained fast swimming, which led to the selection for efficient movement via higher aspect ratio pectoral fins. Swimming performance was likely enhanced in pelagic sharks during this time due to the elevated temperatures in the sea, highlighting that shark evolution has been greatly impacted by climate change.

@article{doi101016jcub202405016,
    author = "Sternes, Phillip C. and Schmitz, Lars and Higham, Timothy E.",
    title = "The rise of pelagic sharks and adaptive evolution of pectoral fin morphology during the Cretaceous",
    year = "2024",
    journal = "Current Biology",
    abstract = "The emergence and subsequent evolution of pectoral fins is a key point in vertebrate evolution, as pectoral fins are dominant control surfaces for locomotion in extant fishes. 1, 2, 3 However, major gaps remain in our understanding of the diversity and evolution of pectoral fins among cartilaginous fishes (Chondrichthyes), a group with an evolutionary history spanning over 400 million years with current selachians (modern sharks) appearing about 200 million years ago. 4, 5, 6 Modern sharks are a charismatic group of vertebrates often thought to be predators roaming the open ocean and coastal areas, but most extant species occupy the seafloor. 4 Here we use an integrative approach to understand what facilitated the expansion to the pelagic realm and what morphological changes accompanied this shift. On the basis of comparative analyses in the framework of a time-calibrated molecular phylogeny, 7 we show that modern sharks expanded to the pelagic realm no later than the Early Cretaceous (Barremian). The pattern of pectoral fin aspect ratios across selachians is congruent with adaptive evolution, and we identify an increase of the subclade disparity of aspect ratio at a time when sea surface temperatures were at their highest. 8 The expansion to open ocean habitats likely involved extended bouts of sustained fast swimming, which led to the selection for efficient movement via higher aspect ratio pectoral fins. Swimming performance was likely enhanced in pelagic sharks during this time due to the elevated temperatures in the sea, highlighting that shark evolution has been greatly impacted by climate change.",
    url = "https://doi.org/10.1016/j.cub.2024.05.016",
    doi = "10.1016/j.cub.2024.05.016",
    openalex = "W4399287119",
    references = "doi101016jzool2020125799, doi101111j10958649201203245x"
}

Seasonal variability in environmental conditions is a strong determinant of animal migrations, but warming temperatures associated with climate change are anticipated to alter this phenomenon with unknown consequences. We used a 40-year fishery-independent survey to assess how a changing climate has altered the migration timing, duration and first-year survival of juvenile bull sharks (Carcharhinus leucas). From 1982 to 2021, estuaries in the western Gulf of Mexico (Texas) experienced a mean increase of 1.55°C in autumn water temperatures, and delays in autumn cold fronts by ca. 0.5 days per year. Bull shark migrations in more northern estuaries concomitantly changed, with departures 25-36 days later in 2021 than in 1982. Later, migrations resulted in reduced overwintering durations by up to 81 days, and the relative abundance of post-overwintering age 0-1 sharks increased by >50% during the 40-year study period. Yet, reductions in prey availability were the most influential factor delaying migrations. Juvenile sharks remained in natal estuaries longer when prey were less abundant. Long-term declines in prey reportedly occurred due to reduced spawning success associated with climate change based on published reports. Consequently, warming waters likely enabled and indirectly caused the observed changes in shark migratory behaviour. As water temperatures continue to rise, bull sharks in the north-western Gulf of Mexico could forgo their winter migrations in the next 50-100 years based on current trends and physiological limits, thereby altering their ecological roles in estuarine ecosystems and recruitment into the adult population. It is unclear if estuarine food webs will be able to support changing residency patterns as climate change affects the spawning success of forage species. We expect these trends are not unique to the western Gulf of Mexico or bull sharks, and migratory patterns of predators in subtropical latitudes are similarly changing at a global scale.

@article{doi1011111365265614140,
    author = "Matich, Philip and Plumlee, Jeffrey D. and Bubley, Walter J. and Curtis, Tobey H. and Drymon, J. Marcus and Mullins, Lindsay and Shipley, Oliver N. and TinHan, Thomas C. and Fisher, Mark",
    title = "Long‐term effects of climate change on juvenile bull shark migratory patterns",
    year = "2024",
    journal = "Journal of Animal Ecology",
    abstract = "Seasonal variability in environmental conditions is a strong determinant of animal migrations, but warming temperatures associated with climate change are anticipated to alter this phenomenon with unknown consequences. We used a 40-year fishery-independent survey to assess how a changing climate has altered the migration timing, duration and first-year survival of juvenile bull sharks (Carcharhinus leucas). From 1982 to 2021, estuaries in the western Gulf of Mexico (Texas) experienced a mean increase of 1.55°C in autumn water temperatures, and delays in autumn cold fronts by ca. 0.5 days per year. Bull shark migrations in more northern estuaries concomitantly changed, with departures 25-36 days later in 2021 than in 1982. Later, migrations resulted in reduced overwintering durations by up to 81 days, and the relative abundance of post-overwintering age 0-1 sharks increased by >50\% during the 40-year study period. Yet, reductions in prey availability were the most influential factor delaying migrations. Juvenile sharks remained in natal estuaries longer when prey were less abundant. Long-term declines in prey reportedly occurred due to reduced spawning success associated with climate change based on published reports. Consequently, warming waters likely enabled and indirectly caused the observed changes in shark migratory behaviour. As water temperatures continue to rise, bull sharks in the north-western Gulf of Mexico could forgo their winter migrations in the next 50-100 years based on current trends and physiological limits, thereby altering their ecological roles in estuarine ecosystems and recruitment into the adult population. It is unclear if estuarine food webs will be able to support changing residency patterns as climate change affects the spawning success of forage species. We expect these trends are not unique to the western Gulf of Mexico or bull sharks, and migratory patterns of predators in subtropical latitudes are similarly changing at a global scale.",
    url = "https://doi.org/10.1111/1365-2656.14140",
    doi = "10.1111/1365-2656.14140",
    openalex = "W4400739204",
    references = "doi101080000284872011618352"
}

Basking sharks (Cetorhinus maximus) seasonally aggregate in coastal surface waters of the North Atlantic, providing opportunities for visual observation. While putative courtship displays have been observed, actual copulation has not been documented. Here we examine video collected by an unmanned aerial vehicle ("drone") of novel behavioral interactions between basking sharks in Cape Cod Bay, Massachusetts in May 2021. The behaviors, including close following and tight concentric circling, are consistent with pre-copulatory behavior observed in other shark species. These observations provide new insights into the pre-copulatory behavior of basking sharks.

@article{doi101111jfb15858,
    author = "Curtis, Tobey H. and Robinson, Jeff and Pratt, Harold and Skomal, Gregory B. and Whitney, Nicholas M.",
    title = "Novel pre‐copulatory behavior in basking sharks observed by drone",
    year = "2024",
    journal = "Journal of Fish Biology",
    abstract = {Basking sharks (Cetorhinus maximus) seasonally aggregate in coastal surface waters of the North Atlantic, providing opportunities for visual observation. While putative courtship displays have been observed, actual copulation has not been documented. Here we examine video collected by an unmanned aerial vehicle ("drone") of novel behavioral interactions between basking sharks in Cape Cod Bay, Massachusetts in May 2021. The behaviors, including close following and tight concentric circling, are consistent with pre-copulatory behavior observed in other shark species. These observations provide new insights into the pre-copulatory behavior of basking sharks.},
    url = "https://doi.org/10.1111/jfb.15858",
    doi = "10.1111/jfb.15858",
    openalex = "W4400341658",
    references = "doi1011631568539xbja10214"
}

= 172.2 cm and k = 0.190 for females. Sexual dimorphism was corroborated, with females reaching larger sizes and presenting slower growth rates than males. The estimated k values were higher than those estimated for rays of similar size to G. altavela in the natural environment, probably due to the constant water temperature (around 25.5°C), food abundance, low population density, reduced predation rates, and high water quality in the captive environment. A comparison of the captivity findings with other studies on G. altavela age and growth in the Atlantic and Mediterranean indicates a broad phenotypic plasticity regarding growth. Three G. altavela reproductions were recorded, with size at birth appearing to be a key factor for pup's survival. Behavioral pattern observations associated with reproduction are also described, encompassing chasing and copulation, whereas the species' internal morphology is described through coelomic cavity ultrasound scanning.

@article{doi101111jfb15862,
    author = "Teixeira-Leite, Clara V. and da Silva, Francisco Marcante Santana and Valle, Rafael Franco and Takasuka, Veronica and de Góes, Matheus Felix and Bonatelli, Shayra Peruch and Santos, Sérgio Ricardo Brito and Vianna, Marcelo",
    title = "Life‐history of the spiny butterfly ray, Gymnura altavela (Chondrichthyes: Myliobatiformes), kept under human care in a marine aquarium",
    year = "2024",
    journal = "Journal of Fish Biology",
    abstract = "= 172.2 cm and k = 0.190 for females. Sexual dimorphism was corroborated, with females reaching larger sizes and presenting slower growth rates than males. The estimated k values were higher than those estimated for rays of similar size to G. altavela in the natural environment, probably due to the constant water temperature (around 25.5°C), food abundance, low population density, reduced predation rates, and high water quality in the captive environment. A comparison of the captivity findings with other studies on G. altavela age and growth in the Atlantic and Mediterranean indicates a broad phenotypic plasticity regarding growth. Three G. altavela reproductions were recorded, with size at birth appearing to be a key factor for pup's survival. Behavioral pattern observations associated with reproduction are also described, encompassing chasing and copulation, whereas the species' internal morphology is described through coelomic cavity ultrasound scanning.",
    url = "https://doi.org/10.1111/jfb.15862",
    doi = "10.1111/jfb.15862",
    openalex = "W4400481317",
    references = "doi1011631568539xbja10214"
}

Over the past two decades, sharks have been increasingly recognized among the world's most threatened wildlife and hence have received heightened scientific and regulatory scrutiny. Yet, the effect of protective regulations on shark fishing mortality has not been evaluated at a global scale. Here we estimate that total fishing mortality increased from at least 76 to 80 million sharks between 2012 and 2019, ~25 million of which were threatened species. Mortality increased by 4% in coastal waters but decreased by 7% in pelagic fisheries, especially across the Atlantic and Western Pacific. By linking fishing mortality data to the global regulatory landscape, we show that widespread legislation designed to prevent shark finning did not reduce mortality but that regional shark fishing or retention bans had some success. These analyses, combined with expert interviews, highlight evidence-based solutions to reverse the continued overexploitation of sharks.

@article{doi101126scienceadf8984,
    author = "Worm, Boris and Orofino, Sara and Burns, Echelle S. and D’Costa, Nidhi G. and Feitosa, Leonardo Manir and Palomares, Maria Lourdes D. and Schiller, Laurenne and Bradley, Darcy",
    title = "Global shark fishing mortality still rising despite widespread regulatory change",
    year = "2024",
    journal = "Science",
    abstract = "Over the past two decades, sharks have been increasingly recognized among the world's most threatened wildlife and hence have received heightened scientific and regulatory scrutiny. Yet, the effect of protective regulations on shark fishing mortality has not been evaluated at a global scale. Here we estimate that total fishing mortality increased from at least 76 to 80 million sharks between 2012 and 2019, \textasciitilde 25 million of which were threatened species. Mortality increased by 4\% in coastal waters but decreased by 7\% in pelagic fisheries, especially across the Atlantic and Western Pacific. By linking fishing mortality data to the global regulatory landscape, we show that widespread legislation designed to prevent shark finning did not reduce mortality but that regional shark fishing or retention bans had some success. These analyses, combined with expert interviews, highlight evidence-based solutions to reverse the continued overexploitation of sharks.",
    url = "https://doi.org/10.1126/science.adf8984",
    doi = "10.1126/science.adf8984",
    openalex = "W4390734215",
    references = "doi101016jcub202108062"
}

In ecosystems, sharks can be predators, competitors, facilitators, nutrient transporters, and food. However, overfishing and other threats have greatly reduced shark populations, altering their roles and effects on ecosystems. We review these changes and implications for ecosystem function and management. Macropredatory sharks are often disproportionately affected by humans but can influence prey and coastal ecosystems, including facilitating carbon sequestration. Like terrestrial predators, sharks may be crucial to ecosystem functioning under climate change. However, large ecosystem effects of sharks are not ubiquitous. Increasing human uses of oceans are changing shark roles, necessitating management consideration. Rebuilding key populations and incorporating shark ecological roles, including less obvious ones, into management efforts are critical for retaining sharks' functional value. Coupled social-ecological frameworks can facilitate these efforts.

@article{doi101126scienceadl2362,
    author = "Dedman, Simon and Moxley, Jerry and Papastamatiou, Yannis P. and Braccini, Matías and Caselle, Jennifer E. and Chapman, Demian D. and Cinner, Joshua E. and Dillon, Erin and Dulvy, Nicholas K. and Dunn, Ruth E. and Espinoza, Mario and Harborne, Alastair R. and Harvey, Euan S. and Heupel, Michelle R. and Huveneers, Charlie and Graham, Nicholas A. J. and Ketchum, James T. and Klinard, Natalie V. and Kock, Alison and Lowe, Christopher G. and MacNeil, M. Aaron and Madin, Elizabeth M. P. and McCauley, Douglas J. and Meekan, Mark G. and Meier, Amelia and Simpfendorfer, Colin A. and Tinker, M. Tim and Winton, Megan V. and Wirsing, Aaron J. and Heithaus, Michael R.",
    title = "Ecological roles and importance of sharks in the Anthropocene Ocean",
    year = "2024",
    journal = "Science",
    abstract = "In ecosystems, sharks can be predators, competitors, facilitators, nutrient transporters, and food. However, overfishing and other threats have greatly reduced shark populations, altering their roles and effects on ecosystems. We review these changes and implications for ecosystem function and management. Macropredatory sharks are often disproportionately affected by humans but can influence prey and coastal ecosystems, including facilitating carbon sequestration. Like terrestrial predators, sharks may be crucial to ecosystem functioning under climate change. However, large ecosystem effects of sharks are not ubiquitous. Increasing human uses of oceans are changing shark roles, necessitating management consideration. Rebuilding key populations and incorporating shark ecological roles, including less obvious ones, into management efforts are critical for retaining sharks' functional value. Coupled social-ecological frameworks can facilitate these efforts.",
    url = "https://doi.org/10.1126/science.adl2362",
    doi = "10.1126/science.adl2362",
    openalex = "W4401211183",
    references = "doi101016jbiocon201502007, doi101016jcub202108062, doi101016jtree201602014"
}

Abstract The effects of the COVID-19 lockdown on wildlife aggression toward humans have received little attention. Records from French Polynesia show that the annual average of about five shark bites on humans from 2009 to 2019 increased significantly to 15 in 2020, despite the virtual absence of humans from the marine environment during a six-week curfew in April–May 2020. Bites then returned to baseline levels in 2021 (), 2022 (), and 2023 (). Most bites in 2020 occurred just after the lockdown and were attributed to gray reef sharks, Carcharhinus amblyrhynchos, displaying territoriality rather than self-defense or predatory behaviours. This temporary increase in shark bites suggests that natural territorial behavior, typically suppressed by continued human presence, reemerged during the Anthropause, providing new insights into shark risks for ocean users and the management of human–predator interactions.

@article{doi1011631568539xbja10279,
    author = "Clua, Éric and Meyer, C.-C. and Séguigne, Clémentine and Wirsing, Aaron J.",
    title = "Increase of coastal shark bite frequency linked to the COVID-19 lockdown reveals a territoriality-dominance behaviour toward humans",
    year = "2024",
    journal = "Behaviour",
    abstract = "Abstract The effects of the COVID-19 lockdown on wildlife aggression toward humans have received little attention. Records from French Polynesia show that the annual average of about five shark bites on humans from 2009 to 2019 increased significantly to 15 in 2020, despite the virtual absence of humans from the marine environment during a six-week curfew in April–May 2020. Bites then returned to baseline levels in 2021 (), 2022 (), and 2023 (). Most bites in 2020 occurred just after the lockdown and were attributed to gray reef sharks, Carcharhinus amblyrhynchos, displaying territoriality rather than self-defense or predatory behaviours. This temporary increase in shark bites suggests that natural territorial behavior, typically suppressed by continued human presence, reemerged during the Anthropause, providing new insights into shark risks for ocean users and the management of human–predator interactions.",
    url = "https://doi.org/10.1163/1568539x-bja10279",
    doi = "10.1163/1568539x-bja10279",
    openalex = "W4401828777",
    references = "doi1011631568539xbja10214"
}

@article{doi1018476palev17a6,
    author = "Böttcher, Ronald",
    title = "Root resorption during tooth replacement in sharks – a unique character of the Hybodontiformes (Chondrichthyes, Elasmobranchii)",
    year = "2024",
    journal = "Palaeodiversity",
    url = "https://doi.org/10.18476/pale.v17.a6",
    doi = "10.18476/pale.v17.a6",
    openalex = "W4405853966",
    references = "doi1010029781119174844, doi101002jmor20370, doi101038001189d0, doi101038001534a0, doi101038nature12617, doi101038nature20806, doi101093nqs5vi146318i, doi101098rspb20240262, doi101111j1469185x200900077x, doi101111j146979981833tb06418x, doi1011552015421746, doi104072rbp2005205, openalexw1545181283, openalexw2894525608"
}

Baited pelagic underwater videos are increasingly being used to assess ecological indices but they can also be effective in recording the behaviour of pelagic species attracted to the bait. In this study, the behaviour of 79 blue sharks Prionace glauca was recorded using drifting pelagic baited remote underwater video system (BRUVS) rigs, deployed outside the Professor Luiz Saldanha Marine Park, Portugal. Juveniles were more frequently sighted over epipelagic (depth between 60 and 200 m) and mesopelagic zones (200-1000 m), while adult sightings were more common further offshore, particularly over canyons (1200-2000 m). Importantly, juvenile sightings were more frequent in spring (breeding season), suggesting that the study area is likely an important nursery habitat. Blue sharks primarily exhibited inspection activities around the BRUVS. Generalised linear models indicated that visibility, distance to the shore, bathymetry and temperature influenced their behavioural patterns. Moreover, juveniles interacted with the BRUVS for a longer time (mean duration: 0.4 min) than adults (0.2 min). A preliminary analysis of blue sharks’ reaction to boat presence suggests that boat noise decreased both the duration of interaction with the BRUVS and the range of observed behaviours. This study provides valuable insights into the behaviour of this species in its natural environment, which is relevant for management and conservation efforts.

@article{doi103354meps14765,
    author = "Ríos, Ney and Jiménez, Manuel and Franco, Gustavo and Ramos, G.H.A. and Pais, Miguel Pessanha and Gonçalves, Emanuel J. and Amorim, MCP and Silva, Gabriel",
    title = "Characterising the behaviour of bait-attracted blue sharks Prionace glauca using pelagic drift video",
    year = "2024",
    journal = "Marine Ecology Progress Series",
    abstract = "Baited pelagic underwater videos are increasingly being used to assess ecological indices but they can also be effective in recording the behaviour of pelagic species attracted to the bait. In this study, the behaviour of 79 blue sharks Prionace glauca was recorded using drifting pelagic baited remote underwater video system (BRUVS) rigs, deployed outside the Professor Luiz Saldanha Marine Park, Portugal. Juveniles were more frequently sighted over epipelagic (depth between 60 and 200 m) and mesopelagic zones (200-1000 m), while adult sightings were more common further offshore, particularly over canyons (1200-2000 m). Importantly, juvenile sightings were more frequent in spring (breeding season), suggesting that the study area is likely an important nursery habitat. Blue sharks primarily exhibited inspection activities around the BRUVS. Generalised linear models indicated that visibility, distance to the shore, bathymetry and temperature influenced their behavioural patterns. Moreover, juveniles interacted with the BRUVS for a longer time (mean duration: 0.4 min) than adults (0.2 min). A preliminary analysis of blue sharks’ reaction to boat presence suggests that boat noise decreased both the duration of interaction with the BRUVS and the range of observed behaviours. This study provides valuable insights into the behaviour of this species in its natural environment, which is relevant for management and conservation efforts.",
    url = "https://doi.org/10.3354/meps14765",
    doi = "10.3354/meps14765",
    openalex = "W4405185480",
    references = "doi1011631568539xbja10214"
}