Environmental Science › Nature and Landscape Conservation

Ichthyology and Marine Biology

Works Count: 37732

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This cluster of papers focuses on the conservation, ecology, and population dynamics of sharks and rays, including their phylogeny, habitat use, migration patterns, and the impact of fisheries on their populations. It also addresses the importance of marine ecosystems and the challenges in managing and protecting these apex predators.

Keywords

Sharks; Rays; Conservation; Ecology; Fisheries; Phylogeny; Habitat Use; Migration; Population Dynamics; Marine Ecosystems

Biology of Sharks and Their Relatives

2022-05-02

Jeffrey C. Carrier , Colin A. Simpfendorfer , Michael R. Heithaus +1 more

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. … 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

Corals of Australia and the Indo-Pacific

1993-12-01

J. E. N. Veron

This gorgeous reference was originally published in 1986 (North Ryde, NSW, Australia: Angus & Robertson) and received the Australian National Awards Whitley Medal for Best Natural History book in 1988. … This gorgeous reference was originally published in 1986 (North Ryde, NSW, Australia: Angus & Robertson) and received the Australian National Awards Whitley Medal for Best Natural History book in 1988. It provides a means of identifying some 1,000 species of coral in all areas of Oceania and Southea

The evolution and interrelationships of the actinopterygian fishes

1983-01-01

George Lauder , Karel F. Liem

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems

2015-06-09

James S. E. Lea , Bradley M. Wetherbee , Nuno Queiroz +7 more

Abstract Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of … Abstract Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier , we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks.

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Biology of Marine Mammals

2000-06-01

M.B. Santos Vázquez

Phyletic Relationships of Living Sharks and Rays

1977-05-01

Leonard J. V. Compagno

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 … 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.

Classification of Fishes, Both Recent and Fossil

1941-11-21

George S. Myers , L. S. Berg

A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History

1998-04-10

Lance Grande , William E. Bemis

ABSTRACT The comparative osteology, phylogenetic relationships, and historical biogeography of all known taxa of fossil and living amiid fishes (Halecomorphi: Amiidae) are investigated in detail. Previously, the detailed osteology of … ABSTRACT The comparative osteology, phylogenetic relationships, and historical biogeography of all known taxa of fossil and living amiid fishes (Halecomorphi: Amiidae) are investigated in detail. Previously, the detailed osteology of nearly all fossil amiids was unknown. We present the first well-supported comprehensive phylogeny for fossil and living amiid fishes. We synthesize clearly documented phylogenetic data on amiids and other halecomorph fishes with other historical phenomena such as ontogeny, historical biogeography, stratigraphic paleontology, and paleoecology (both “stationary” and “historical”). We also use our study of halecomorph fishes as a platform to explore several fundamental methodological and theoretical concepts important to phylogenetic/evolutionary investigations. These concepts pertain mainly to (1) the use of comparative empirical data to interpret various historical patterns and (2) the practice of integrating fossil and living species together in original (i.e., non-literature-based) phylogenetic studies. As proposed by Patterson (1973), Amia calva is the sole surviving member of a formerly diverse clade, Halecomorphi. Even Amiidae (the halecomorph subgroup that is the focus of this study) was taxonomically diverse and widespread during Mesozoic and Paleogene times. Amiidae here includes only those amiiform fishes that have solid perichordally ossified diplospondylous centra of both the “normal” (a term used here for non-alternating) and the alternating type in the caudal region. Consequently, †Sinamiidae and †Caturoidea (†Caturidae plus †Liodesmidae) are excluded from the family Amiidae. To set the style and terminology for description of the fossil taxa, and to present a fresh look at the osteology and development of the only living amiiform, we redescribe Amia calva in detail using modern methods of preparation and illustration. Detailed study of Amia calva is critical for interpreting probable intraspecific variation and ontogeny in fossil skeletons. We examined individual variation of both bone morphology and developmental timing in Amia calva. We classify the family Amiidae into four subfamilies here: †Amiinae (including †Amia, †Cyclurus, †Pseudamiatus, and † “Amia” hesperia), †Vidalamiinae subfam. nov. (including † Vidalamia, †Pachyamia, †Melvius, †Calamopleurus, and †Maliamia), †Solnhofenamiinae subfam. nov. (including †Solnhofenamia gen. nov.), and †Amiopsinae subfam. nov. (including †Amiopsis). The genus †Nipponamia remains Amiidae subfamily indeterminate until additional material can be found and studied, although it does not appear to belong to Amiinae or †Amiopsinae subfam. nov. as defined here. Other nominal genera of Amiidae are discussed as nomina nuda or nomina dubia. We found Amiinae to be a clearly monophyletic group diagnosed by numerous synapomorphic characters. This is the only amiid (and halecomorph) subfamily known to have survived beyond the early Eoccne. It was a diverse group with a known stratigraphic range of Late Cretaceous through the present. The earliest diagnosable species in the subfamily is †Cyclurus fragosus from the upper Maastrichtian of Alberta, Canada, and the earliest Amiinae indeterminate is a collection of fragments from the upper Cenomanian of Uzbekhistan (“?Amia semimarina” Nessov 1985, a nomen dubium). Earlier forms reported by Boreske (1974) could not be verified as Amiinae. Amiinae was widespread and particularly speciose during the Eocene, and appears to have been confined almost exclusively to fresh water. The extremely rare amiine fossil fragments from brackish water deposits probably represent accidental or, at most, occasional migration into brackish environments or possibly entrapment in a drying water system. Amiinae includes three valid species of Amia (including †A. pattersoni sp. nov.), eight valid species of †Cyclurus (all of which are described here), and † “Amia” hesperia (a valid species of uncertain generic affinity). It also includes the genus †Pseudamiatus which remains †Amiinae indeterminate, until the type and only known specimen can be further prepared or until additional material can be found. It probably belongs in Amia or †Cyclurus as those genera are defined here. We also review more than 30 other nominal species of amiines, all of which we believe are invalid names (either nomina dubia, nominanuda, or subjective junior synonyms) but some of which nevertheless extend the stratigraphic and geographic range of the subfamily Amiinae. Although we clarify the known diversity and monophyly of Amiinae, and add new morphological information about numerous amiine species, further materials and work are needed to resolve phylogenetic interrelationships within this subfamily. †Vidalamiinae subfam. nov. is a previously unrecognized, diverse group of amiid taxa, several of which reach very large sizes (to about two meters total length). This well-supported monophyletic subfamily is known only from the Early Cretaceous to the early Eocene, and contains two well-supported monophyletic subgroups: †Vidalamiini tribe nov. and †Calamopleurini tribe nov. These tribes have interesting biogeographic distributions that seem incongruent with today's geography, but these distributions make intuitive sense given current interpretations of the paleogeography of the Early Cretaceous (illustrated here). †Vidalamiini tribe nov. includes †Vidalamia (one species from coastal estuarine/lagoonal deposits of Spain), †Pachyamia (two species: one from marine deposits of the Middle East and a new species from marine deposits in Mexico) and †Melvius (two species from deposits along the margin of the Upper Cretaceous North American Seaway). During the Early Cretaceous, this seemingly far-flung distribution was connected by a continuous shallow marine continental margin and seaway. All five species of †Vidalamiini tribe nov. are described in detail here. †Calamopleurini tribe nov. includes †Calamopleurus (three species: one from an inconclusively determined paleoenvironment of eastern Brazil, one species from a probable freshwater paleoenvironment of eastern Brazil, and a new species from a yet unknown paleoenvironment of Morocco) and †Maliamia (one species from west-central Africa in deposits of unknown water chemistry). Most of these species (particularly †C. cylindricus) are described in detail here. †Vidalamiinae subfam. nov. is the sister group to Amiinae, and the two subfamilies together form the supersubfamily Amiista nuper interposita. The term “nuper interposita” is introduced here to indicate the first published use of new names inserted between existing family group names. †Solnhofenamiinae subfam. nov. is a Late Jurassic marine group from Europe (Germany and France) currently containing a single species, †Solnhofenamia elongata gen. nov. This species was formerly placed in the genus † Urocles as † “Urocles” elongatus. However, the genus † Urocles is invalid in our scheme because the type species of †Urocles is congeneric with †Amiopsis, and the name †Amiopsis has priority. We find that † “Urocles” elongatus is more closely related to a group containing Amiinae plus †Vidalamiinae subfam. nov., than it is to the type species of the genus †Urocles (= †Amiopsis lepidota here). Therefore, we place †“Urocles” elongatus in the new genus †Solnhofenamia. Because †S. elongata gen. nov. is the sister group to a group containing Amiinae plus †Vidalamiinae subfam. nov., we put it into †Solnhofenamiinae subfam. nov. We describe this species in detail for the first time. †Amiopsinae subfam. nov. is a poorly supported stem group of amiids from Late Jurassic to late Cretaceous (Turonian) marine and freshwater deposits of Europe (Yugoslavia, Germany, Spain, England, Belgium, and possibly France). This group, with five valid species, may be non-monophyletic. †Amiopsinae subfam. nov. contains most of the amiids excluded from the hypersubfamily Amiida nuper interposita, a monophyletic group containing ((Amiinae + †Vidalamiinae subfam. nov.) + †Solnhofenamiinae subfam. nov.). All five species of †Amiopsis are described here with much new detail. The phylogenetic position and biogeographic significance of the single known, poorly preserved specimen of †Nipponamia, from Early Cretaceous freshwater deposits of Japan, is largely unknown. Additional material is needed to better understand its morphology. In addition to our cladogram of Amiidae, we produced a cladogram of Halecomorphi. Our sample of non-amiid halecomorph taxa was far less complete than our sample of amiid taxa; nevertheless we found several well-supported nodes within non-amiid halecomorphs which can serve as general guides for future research. We discuss numerous general methodological, philosophical, and theoretical concepts in this paper, including the construction of taxonomic diagnoses, the treatment of undiagnosable taxa, and the treatment of ontogenetically variable characters. We review the effects on phylogenetic analysis of problematic (e.g., “missing”) data entries resulting from either problematic taxa (e.g., highly incomplete fossil taxa) or problematic characters (characters whose states are unknown for most taxa). Various types of problematic data are also reviewed. We discuss the exclusion of certain problematic taxa (here termed “inserted” taxa) and problematic characters (here termed “mapped” characters) from phylogenetic analyses. We also examine the effects of phylogenetically “redundant” taxa and consider the comparative value of wellresolved nodes versus completely resolved trees in cladistic studies. These concepts and terms can all be located in this volume by using the table of contents or the subject index. Our study exemplifies the large amount of natural historical information that can be interpreted from multidisciplinary pattern studies of fossil and living actinopterygian fishes. We term our general approach to the study of natural history as “an empirical synthetic pattern approach”, an exploratory method whose fundamentals go back to the 19th century naturalist Louis Agassiz (1807–1873). Many other actinopterygian groups of equal potential remain virtually unstudied with regard to their broad historical significance (e.g., phylogenetic pattern congruence between comparative morphology, ontogeny, biogeography, and stratigraphy). Exceptional preservation and abundant poorly known material make fossil actinopterygians one of the greatest remaining frontiers in vertebrate paleontology.

Rates of mitochondrial DNA evolution in sharks are slow compared with mammals

1992-05-01

Andrew Martin , Gavin J. P. Naylor , Stephen R. Palumbi

Fishery Stability, Local Extinctions, and Shifts in Community Structure in Skates

2000-02-01

Nicholas K. Dulvy , Julian D. Metcalfe , Jamie Glanville +2 more

Abstract: Skates are arguably the most vulnerable of exploited marine fishes. Their vulnerability is often assessed by examining fisheries catch trends, but these data are not generally recorded on a … Abstract: Skates are arguably the most vulnerable of exploited marine fishes. Their vulnerability is often assessed by examining fisheries catch trends, but these data are not generally recorded on a species basis except in France. Aggregated skate catch statistics tend to exhibit more stable trends than those of other elasmobranch fisheries. We tested whether such apparent stability in aggregated catch trends could mask population declines of individual species. We examined two time series of species‐specific surveys of a relatively stable skate fishery in the northeast Atlantic. These surveys revealed the disappearance of two skate species, long‐nose skate ( Dipturus oxyrhinchus ) and white skate ( Rostroraja alba ) and confirmed a previously documented decline of the common skate ( D. batis ). Of the remaining five skate species, the three larger ones have declined, whereas two smaller species have increased in abundance. The increase in abundance and biomass of the smaller species has resulted in the stability of the aggregated catch trends. Because there is significant dietary overlap among species, we suggest the increase in abundance of the smaller species may be due to competitive release as the larger species declined. A consequence of this kind of stability is that declining species cannot be detected without species‐specific data, especially in taxa exhibiting competitive interactions. This may explain why previously documented disappearances of two species of skates went unnoticed for so long. The conservation of skates and other elasmobranchs requires species‐specific monitoring and special attention to larger species.

Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean

2007-03-30

Ransom A. Myers , Julia K. Baum , Travis D. Shepherd +2 more

Impacts of chronic overfishing are evident in population depletions worldwide, yet indirect ecosystem effects induced by predator removal from oceanic food webs remain unpredictable. As abundances of all 11 great … Impacts of chronic overfishing are evident in population depletions worldwide, yet indirect ecosystem effects induced by predator removal from oceanic food webs remain unpredictable. As abundances of all 11 great sharks that consume other elasmobranchs (rays, skates, and small sharks) fell over the past 35 years, 12 of 14 of these prey species increased in coastal northwest Atlantic ecosystems. Effects of this community restructuring have cascaded downward from the cownose ray, whose enhanced predation on its bay scallop prey was sufficient to terminate a century-long scallop fishery. Analogous top-down effects may be a predictable consequence of eliminating entire functional groups of predators.

Life History Patterns and Correlations in Sharks

2000-01-01

Enric Cortés

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 … 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.

The outgrowth of the nerve fiber as a mode of protoplasmic movement

1959-10-01

Ross Harrison

Elephant shark genome provides unique insights into gnathostome evolution

2014-01-07

Byrappa Venkatesh , Alison Lee , Vydianathan Ravi +7 more

The emergence of jawed vertebrates (gnathostomes) from jawless vertebrates was accompanied by major morphological and physiological innovations, such as hinged jaws, paired fins and immunoglobulin-based adaptive immunity. Gnathostomes subsequently diverged … The emergence of jawed vertebrates (gnathostomes) from jawless vertebrates was accompanied by major morphological and physiological innovations, such as hinged jaws, paired fins and immunoglobulin-based adaptive immunity. Gnathostomes subsequently diverged into two groups, the cartilaginous fishes and the bony vertebrates. Here we report the whole-genome analysis of a cartilaginous fish, the elephant shark (Callorhinchus milii). We find that the C. milii genome is the slowest evolving of all known vertebrates, including the 'living fossil' coelacanth, and features extensive synteny conservation with tetrapod genomes, making it a good model for comparative analyses of gnathostome genomes. Our functional studies suggest that the lack of genes encoding secreted calcium-binding phosphoproteins in cartilaginous fishes explains the absence of bone in their endoskeleton. Furthermore, the adaptive immune system of cartilaginous fishes is unusual: it lacks the canonical CD4 co-receptor and most transcription factors, cytokines and cytokine receptors related to the CD4 lineage, despite the presence of polymorphic major histocompatibility complex class II molecules. It thus presents a new model for understanding the origin of adaptive immunity. Whole-genome analysis of the elephant shark, a cartilaginous fish, shows that it is the slowest evolving of all known vertebrates, lacks critical bone formation genes and has an unusual adaptive immune system. The elephant shark (Callorhinchus milii) is a cartilaginous fish native to the temperate waters off southern Australia and New Zealand, living at depths of 200 to 500 metres and migrating into shallow waters during spring for breeding. The genome sequence is published in this issue of Nature. Comparison with other vertebrate genomes shows that it is the slowest evolving genome of all known vertebrates — coelacanth included. Genome analysis points to an unusual adaptive immune system lacking the CD4 receptor and some associated cytokines, indicating that cartilaginous fishes possess a primordial gnathostome adaptive immune system. Also absent are genes encoding secreted calcium-binding phosphoproteins, in line with the absence of bone in cartilaginous fish.

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Viviparity: The Maternal-Fetal Relationship in Fishes

1981-05-01

John P. Wourms

SYNOPSIS. Viviparity in the vertebrate line first makes its evolutionary appearance among fishes. It has independently evolved in a number of divergent piscine lineages. The 54 families of extant fishes … SYNOPSIS. Viviparity in the vertebrate line first makes its evolutionary appearance among fishes. It has independently evolved in a number of divergent piscine lineages. The 54 families of extant fishes that bear living young include 40 families of chondrichthyans (sharks and rays), one montypic family of coelacanths (Latimeria), and 13 families of teleosts. There is fossil evidence for viviparity in holocephalans and chondrosteans. Viviparity predominates among sharks and rays (40 families, 99 genera, 420 species) but is less widespread among teleosts (13 families, 122 genera, 510 species). Following an historical introduction, the organization of the female reproductive system, sites of gestation, developmental sequences and superfetation are considered. The evolution of viviparity establishes specialized maternal-fetal relationships, viz., 1) developmental, 2) morphological, 3) trophic, 4) osmoregulatory, 5) respiratory, 6) endocrinological, and 7) immunological. While the latter four categories are briefly noted the major emphasis is on the trophic relationship and its morphological and developmental basis. First, a general overview is presented and then the maternal-fetal trophic relationships in each of the major groups of fishes are systematically reviewed. Pertinent anatomical, histological, ultrastructural, developmental, physiological, and biochemical studies are considered. Viviparous fishes are either lecithotrophic, i.e., exclusively yolk dependent, or matrotrophic, i.e., in receipt of a continuous supply of maternal nutrients during gestation. Nutrient transfer is accomplished by 1) oophagy and adelphophagy, 2) placental analogues, and 3) the yolk sac placenta. Placental analogues include: external epithelial absorptive surfaces, e.g., skin, fins, gills; trophonemata, modifications of the uterine epithelia for the secretion of histotrophe or "uterine milk"; branchial placentae, close apposition between gill epithelia and either uterine or ovarian epithelial villi; the yolk sac; pericardial amnion and chorion; follicular pseudoplacenta, close apposition between follicle cells and embryonic absorptive epithelia; hypertrophied gut; and trophotaeniae, external rosette or ribbon-like projections of the embryonic gut. Among chondrichthyans, the yolk sac placenta (840–1,050%), trophonematal secretion and embryonic absorbtion of histotrophe (1,680–4,900%) and oophagy and adelphophagy (1.2 × 106%) are the most efficient methods of nutrient transfer. Among teleosts, the follicular pseudoplacenta (1,800–3,900%), trophotaeniae (8,400%) and absorption of ovarian histotrophe through surface epithelia and a hypertrophied gut (1,100–34,000%) are the most efficient. These values stand in contrast to the 30%40% loss of dry weight characteristic of oviparous fishes and viviparous lecithotrophes.

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Phylogenies without roots? A plea for the use of vouchers in molecular phylogenetic studies

2008-03-25

Fredrik Pleijel , Ulf Jondelius , Erika Norlinder +5 more

Shark nursery areas: concepts, definition, characterization and assumptions

2007-05-14

Michelle R. Heupel , JK Carlson , Colin A. Simpfendorfer

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 337:287-297 (2007) - doi:10.3354/meps337287 … MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 337:287-297 (2007) - doi:10.3354/meps337287 Shark nursery areas: concepts, definition, characterization and assumptions Michelle R. Heupel1,*, John K. Carlson2, Colin A. Simpfendorfer3 1Center for Shark Research, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, Florida 34236, USA 2NOAA, National Marine Fisheries Service, Southeast Fisheries Science Center, 3500 Delwood Beach Road, Panama City, Florida 32408, USA 3School of Earth and Environmental Sciences, James Cook University, Queensland 4811, Australia *Email: [email protected] 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. KEY WORDS: Nursery area · Shark · Habitat · Definition Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 337. Online publication date: May 14, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

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Resolution of ray-finned fish phylogeny and timing of diversification

2012-08-06

Thomas J. Near , Ron I. Eytan , Alex Dornburg +6 more

Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for genomics and developmental … Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for genomics and developmental biology, and the dominant component of marine and freshwater vertebrate faunas. Despite the economic and scientific importance of ray-finned fishes, the lack of a single comprehensive phylogeny with corresponding divergence-time estimates has limited our understanding of the evolution and diversification of this radiation. Our analyses, which use multiple nuclear gene sequences in conjunction with 36 fossil age constraints, result in a well-supported phylogeny of all major ray-finned fish lineages and molecular age estimates that are generally consistent with the fossil record. This phylogeny informs three long-standing problems: specifically identifying elopomorphs (eels and tarpons) as the sister lineage of all other teleosts, providing a unique hypothesis on the radiation of early euteleosts, and offering a promising strategy for resolution of the "bush at the top of the tree" that includes percomorphs and other spiny-finned teleosts. Contrasting our divergence time estimates with studies using a single nuclear gene or whole mitochondrial genomes, we find that the former underestimates ages of the oldest ray-finned fish divergences, but the latter dramatically overestimates ages for derived teleost lineages. Our time-calibrated phylogeny reveals that much of the diversification leading to extant groups of teleosts occurred between the late Mesozoic and early Cenozoic, identifying this period as the "Second Age of Fishes."

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Interrelationships of Fishes

1997-08-01

Joseph S. Nelson , Melanie L. J. Stiassny , Lynne R. Parenti +1 more

Introduction, M.L.J. Stiassny et al an annotated bibliography of the work of Colin Patterson, B. Schaeffer and B.G. Gardiner morphology, characters and the interrelationships of basal sarcopterygians, R. Cloutier and … Introduction, M.L.J. Stiassny et al an annotated bibliography of the work of Colin Patterson, B. Schaeffer and B.G. Gardiner morphology, characters and the interrelationships of basal sarcopterygians, R. Cloutier and P.E. Ahlberg phylogenetic interrelationship of the living euselachians (chondrichthys), S. Shirai higher-level elasmobranch phylogeny, basal squaleans and paraphyly, M.R. de Carvalho interrelationships of the batoid fishes (chondrichthyes - batoidea), J.D. McEachran et al interrelationships of basal neopterygians, B.G. Gardiner et al interrelationships of acipenseriformes, with comments on chondrostei, L. Grande and W.E. Bemis teleostean monophyly, M.C.C. de Pinna phylogeny on osteoglossomorpha, L. Guo-qing and M.V.H. Wilson interrelationships of elopomorph fishes, P.L. Forey et al clupeomorpha, sistergroup of ostariophysi, G. Lecointre and G. Nelson interrelationships of ostariophysan fishes (teleostei), S.V. Fink and W.L. Fink relationships of lower euteleostean fishes, G.D. Johnson and C. Patterson interrelationships of stomiiform fishes, A.S. Harold and S.H. Weitzman aulopiform interrelationships, C.C. Baldwin and G.D. Johnson basal ctenosquamate relationships and the intrarelationships of the myctophiform (scopelomorph) fishes, M.L.J. Stiassny phylogenetic significance of the pectoral/pelvic fin association in acanthomorph fishes - a reassessment using comparative neuroanatomy, L.R. Parenti and J. Song summary, M.L.J. Stiassny et al.

Sharks and Rays of Australia

1994-12-19

Victor G. Springer , Peter R. Last , JD Stevens

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 … 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.

Global catches, exploitation rates, and rebuilding options for sharks

2013-03-01

Boris Worm , Brendal Davis , Lisa Elena Kettemer +5 more

Transoceanic Migration, Spatial Dynamics, and Population Linkages of White Sharks

2005-10-06

Ramón Bonfil , Michael A. Meÿer , Michael C. Scholl +6 more

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 … 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.

Extinction risk and conservation of the world’s sharks and rays

2014-01-21

Nicholas K. Dulvy , Sarah Fowler , John A. Musick +7 more

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 … 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.

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Intrinsic rebound potentials of 26 species of Pacific sharks

1998-01-01

Susan E. Smith , David W. Au , Christina Show

A demographic technique is used to compare the intrinsic rates of population increase of 26 shark species hypothetically exposed to fishing mortality. These rates (r2M) are used as a measure … A demographic technique is used to compare the intrinsic rates of population increase of 26 shark species hypothetically exposed to fishing mortality. These rates (r2M) 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 (r2M < 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 (r2M = 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 r2M, and recommended areas of research are discussed.

Collapse and Conservation of Shark Populations in the Northwest Atlantic

2003-01-16

Julia K. Baum , Ransom A. Myers , Daniel G. Kehler +3 more

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, … 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.

Reproduction and Development in Chondrichthyan Fishes

1977-05-01

John P. Wourms

Patterns of chondrichthyan reproduction and development are diverse. Species either are reproductively active throughout the year, or have a poorly defined annual cycle with one or two peaks of activity, … Patterns of chondrichthyan reproduction and development are diverse. Species either are reproductively active throughout the year, or have a poorly defined annual cycle with one or two peaks of activity, or have a well defined annual or biennial cycle. Based on embryological origin and adult morphology, their reproductive system is more similar to tetrapods than to teleosts. Primordial germ cells are of endodermal origin. The Wolffian ducts in males and Mullerian ducts in females become the functional urogenital ducts. Differentiation is under hormonal control. Unusual features of the reproductive system include an epigonal organ in males and females. It contains lymphoid and hemopoietic tissue. Leydig's gland, a modified region of the kidney, produces seminal fluid. In some species, sperm passing through the vas deferens, is enclosed in spermatophores. Rotating about their long axis, helical spermatozoa can move forward or reverse direction. Spermatogenesis often occurs in bicellular units, spermatocysts. These consist of a spermatogonium enclosed in a Sertoh cell. Fertilization is internal. Claspers, modified portions of the pelvic fins act as intromittent organs. In many viviparous sharks and rays, the female reproductive system is asymmetrical. Eggs of some sharks are the largest known cells. Yolk platelets contain lipovitellin. Oocytes have lampbrush chromosomes. Eggs released from the ovary into the body cavity are transported by ciliary action to the ostium of the oviduct. There they are fertilized. Physiological polyspermy is normal. The shell gland, a specialized region of the anterior oviduct, functions both in long term sperm storage and in egg case production. Egg cases of sharks and skates consist of unique collagenous protein with a 400 Å period, organized as a cholesteric liquid crystal. Chimaeroid egg cases contain 550 Å pseudotubules in orthogonal lattices. In small sharks, males copulate by coiling around the female. A parallel position is assumed by large sharks. Skates and rays copulate with ventral surfaces apposed or by a dorsal approach. Biting is a pre-copulatory release mechanism. Parental care, except for selective oviposition, is lacking. Heavily yolked eggs undergo meroblastic, discoidal cleavage. Development is lengthy, shortest (2–4 months) in rays, longer in skates (3–8 months) and longest (9–22 months) in sharks and chimaeras. Most sharks and all rays are viviparous. Chimaeras, skates, and some sharks are oviparous. Viviparity either involves a yolk sac placenta or is aplacental. If aplacental, the embryo derives nutrients either from yolk reserves, or by intra-uterine embryonic cannibalism, or from placental analogues which secrete "uterine milk." Phylogenetic position, geographical distribution, benthic vs. pelagic habitat, adult size, egg-embryo size, feeding ecology, and embryonic osmoregulation are factors in the retention of oviparity or the evolution of viviparity.

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The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems

2000-06-01

John D. Stevens

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 … 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.

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Standardized diet compositions and trophic levels of sharks

1999-10-01

Enric Cortés

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 … 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 (rs=0.33), with the fit increasing (rs=0.41) when the three predominantly zooplanktivorous sharks were omitted, and especially when considering only carcharhinid sharks (rs=0.55).

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A CRYSTALLOGRAPHIC STUDY OF VERTEBRATE OTOLITHS

1963-12-01

D. Carlström

1. The crystallographic properties of otoliths from 58 vertebrate species were investigated by means of polarization microscopy and x-ray diffraction.2. The otoliths occur as statoconia, microstatoliths, and statoliths. Usually only … 1. The crystallographic properties of otoliths from 58 vertebrate species were investigated by means of polarization microscopy and x-ray diffraction.2. The otoliths occur as statoconia, microstatoliths, and statoliths. Usually only one kind is present in the labyrinth but in some vertebrates a combination of two or all three types may be found.3. While statoliths and microstatoliths always are polycrystalline, statoconia may either be polycrystalline or single crystals.4. Five different minerals, viz., apatite, calcite, aragonite, vaterite and calcium carbonate monohydrate, compose the endogenous otoliths in the vertebrate labycarbonate monohydrate, compose the endogenous otoliths in the vertebrate labyrinth. Some elasmobranchs have in addition exogenous statoconia consisting of sea-sand.5. The distribution of statoliths and/or statoconia, their texture and their composition within the vertebrate series, show remarkable consistencies; within each class the same kind of static bodies is usually present.6. Some crystallographic and biological aspects are discussed and it is suggested that the findings may be of some value for the study of the phylogeny of vertebrates and also may aid towards a better understanding of the function of the otolith organ.

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Loss of Large Predatory Sharks from the Mediterranean Sea

2008-06-10

Francesco Ferretti , Ransom A. Myers , Fabrizio Serena +1 more

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 … 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.

Global estimates of shark catches using trade records from commercial markets

2006-09-15

Shelley Clarke , Murdoch K. McAllister , E.J. Milner‐Gulland +6 more

Despite growing concerns about overexploitation of sharks, lack of accurate, species-specific harvest data often hampers quantitative stock assessment. In such cases, trade studies can provide insights into exploitation unavailable from … Despite growing concerns about overexploitation of sharks, lack of accurate, species-specific harvest data often hampers quantitative stock assessment. In such cases, trade studies can provide insights into exploitation unavailable from traditional monitoring. We applied Bayesian statistical methods to trade data in combination with genetic identification to estimate by species, the annual number of globally traded shark fins, the most commercially valuable product from a group of species often unrecorded in harvest statistics. Our results provide the first fishery-independent estimate of the scale of shark catches worldwide and indicate that shark biomass in the fin trade is three to four times higher than shark catch figures reported in the only global data base. Comparison of our estimates to approximated stock assessment reference points for one of the most commonly traded species, blue shark, suggests that current trade volumes in numbers of sharks are close to or possibly exceeding the maximum sustainable yield levels.

Shifting baselines and the decline of pelagic sharks in the Gulf of Mexico

2004-02-01

Julia K. Baum , Ransom A. Myers

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, … 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.

A DNA Sequence–Based Approach To the Identification of Shark and Ray Species and Its Implications for Global Elasmobranch Diversity and Parasitology

2012-06-21

Gavin J. P. Naylor , Janine N. Caira , Kirsten Jensen +3 more

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 … 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.

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You can swim but you can't hide: the global status and conservation of oceanic pelagic sharks and rays

2008-05-22

Nicholas K. Dulvy , Julia K. Baum , Shelley Clarke +7 more

1. Fishing spans all oceans and the impact on ocean predators such as sharks and rays is largely unknown. A lack of data and complicated jurisdictional issues present particular challenges … 1. Fishing spans all oceans and the impact on ocean predators such as sharks and rays is largely unknown. A lack of data and complicated jurisdictional issues present particular challenges for assessing and conserving high seas biodiversity. It is clear, however, that pelagic sharks and rays of the open ocean are subject to high and often unrestricted levels of mortality from bycatch and targeted fisheries for their meat and valuable fins. 2. These species exhibit a wide range of life-history characteristics, but many have relatively low productivity and consequently relatively high intrinsic vulnerability to over-exploitation. The IUCN — World Conservation Union Red List criteria were used to assess the global status of 21 oceanic pelagic shark and ray species. 3. Three-quarters (16) of these species are classified as Threatened or Near Threatened. Eleven species are globally threatened with higher risk of extinction: the giant devilray is Endangered, ten sharks are Vulnerable and a further five species are Near Threatened. Threat status depends on the interaction between the demographic resilience of the species and intensity of fisheries exploitation. 4. 4. Most threatened species, like the shortfin mako shark, have low population increase rates and suffer high fishing mortality throughout their range. Species with a lower risk of extinction have either fast, resilient life histories (e.g. pelagic stingray) or are species with slow, less resilient life histories but subject to fisheries management (e.g. salmon shark). 5. 5. Recommendations, including implementing and enforcing finning bans and catch limits, are made to guide effective conservation and management of these sharks and rays. Copyright © 2008 John Wiley & Sons, Ltd.

Patterns and ecosystem consequences of shark declines in the ocean

2010-05-27

Francesco Ferretti , Boris Worm , Gregory L. Britten +2 more

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 … 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.

Major patterns of higher teleostean phylogenies: a new perspective based on 100 complete mitochondrial DNA sequences

2002-12-10

Masaki Miya , Hirohiko Takeshima , Hiromitsu Endo +7 more

Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeographical diversity

2016-02-10

Simon Weigmann

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, … 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.

Review of Ichthyodectiform and Other Mesozoic Teleost Fishes and the Theory and Practice of Classifying Fossils.

1977-09-01

Philip D. Gingerich , Colin Patterson , Donn Eric Rosen

Recherches sur les poissons fossiles ...

1833-01-01

Louis Agassiz

POISSO]\S POISSO]\S

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Phylogenetic classification of bony fishes

2017-07-06

Ricardo Betancur‐R , E. O. Wiley , Gloria Arratia +5 more

Fish classifications, as those of most other taxonomic groups, are being transformed drastically as new molecular phylogenies provide support for natural groups that were unanticipated by previous studies. A brief … Fish classifications, as those of most other taxonomic groups, are being transformed drastically as new molecular phylogenies provide support for natural groups that were unanticipated by previous studies. A brief review of the main criteria used by ichthyologists to define their classifications during the last 50 years, however, reveals slow progress towards using an explicit phylogenetic framework. Instead, the trend has been to rely, in varying degrees, on deep-rooted anatomical concepts and authority, often mixing taxa with explicit phylogenetic support with arbitrary groupings. Two leading sources in ichthyology frequently used for fish classifications (JS Nelson's volumes of Fishes of the World and W. Eschmeyer's Catalog of Fishes) fail to adopt a global phylogenetic framework despite much recent progress made towards the resolution of the fish Tree of Life. The first explicit phylogenetic classification of bony fishes was published in 2013, based on a comprehensive molecular phylogeny ( www.deepfin.org ). We here update the first version of that classification by incorporating the most recent phylogenetic results. The updated classification presented here is based on phylogenies inferred using molecular and genomic data for nearly 2000 fishes. A total of 72 orders (and 79 suborders) are recognized in this version, compared with 66 orders in version 1. The phylogeny resolves placement of 410 families, or ~80% of the total of 514 families of bony fishes currently recognized. The ordinal status of 30 percomorph families included in this study, however, remains uncertain (incertae sedis in the series Carangaria, Ovalentaria, or Eupercaria). Comments to support taxonomic decisions and comparisons with conflicting taxonomic groups proposed by others are presented. We also highlight cases were morphological support exist for the groups being classified. This version of the phylogenetic classification of bony fishes is substantially improved, providing resolution for more taxa than previous versions, based on more densely sampled phylogenetic trees. The classification presented in this study represents, unlike any other, the most up-to-date hypothesis of the Tree of Life of fishes.

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Half a century of global decline in oceanic sharks and rays

2021-01-27

Nathan Pacoureau , Cassandra L. Rigby , Peter M. Kyne +7 more

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Overfishing drives over one-third of all sharks and rays toward a global extinction crisis

2021-09-06

Nicholas K. Dulvy , Nathan Pacoureau , Cassandra L. Rigby +7 more

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 … 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.

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Predicting patterns of prey use from morphology of fishes

1995-10-01

Peter C. Wainwright , Barton A. Richard

The outgrowth of the nerve fiber as a mode of protoplasmic movement

1910-12-01

Ross Harrison

Biology of sharks and their relatives

2004-11-01

Living on the Extinction Edge: Resilience to Fishing and Rebound Potential of the Mediterranean Elasmobranchs

2025-06-25

Stefano Moro , Salvatore Valente , M. Arcioni +7 more | Fish and Fisheries

ABSTRACT Mediterranean elasmobranchs are experiencing significant declines due to intense fishing activities, making the region a global hotspot for elasmobranch conservation concerns. These declines are worsened by limited fisheries data, … ABSTRACT Mediterranean elasmobranchs are experiencing significant declines due to intense fishing activities, making the region a global hotspot for elasmobranch conservation concerns. These declines are worsened by limited fisheries data, constraining stock assessments and evidence‐based management. Demographic models based on life history parameters (e.g., survival rate, age‐at‐maturity, litter size and longevity) offer critical alternatives for estimating population productivity in data‐poor contexts. In this study, we estimated the intrinsic rate of population increase () for 82 stocks across 51 species of Mediterranean sharks and rays to assess their relative capacity for recovery under hypothetical sustainable exploitation scenarios. Using demographic modelling and updated life history data, we provide a comparative analysis of species‐specific productivity and identify those with the lowest recovery potential. Many IUCN‐listed threatened species exhibited very low rebound potential, highlighting their vulnerability to fishing. Significant data gaps, especially for pelagic and deep‐sea taxa, underscore the need for targeted life history research. Our results also showed how the rebound potential can provide valuable insight for data‐deficient species, supporting informed assessments with limited biological input. Furthermore, we confirmed that age‐at‐maturity is a valid proxy of when other parameters are unavailable. This study delivers a comprehensive, regional‐scale productivity baseline for Mediterranean elasmobranchs, providing essential input for prioritising species‐specific conservation actions, guiding fishery policy development and improving regional compliance with international conservation frameworks. By addressing critical data limitations, our approach enhances the scientific foundation necessary for the sustainable management and recovery of shark and ray populations in the Mediterranean Sea.

Mixed stock analysis of major markets and trade records reveals illegal trade of oceanic whitetip shark fins from the Atlantic ocean

2025-06-25

Candace Y. A. Fields , Diego Cardeñosa , Andrea M. Bernard +7 more | Conservation Genetics

Ecological interactions and genomic innovation fueled the evolution of ray-finned fish endothermy

2025-06-25

Fernando Meléndez-Vazquez , Alexander G. Lucaci , Avery Selberg +7 more | Science Advances

Endothermy has independently evolved in several vertebrate lineages but remains rare among fishes. Using an integrated approach combining phylogenomic and ecomorphological data for 1051 ray-finned fishes, a time-dependent evolutionary model, … Endothermy has independently evolved in several vertebrate lineages but remains rare among fishes. Using an integrated approach combining phylogenomic and ecomorphological data for 1051 ray-finned fishes, a time-dependent evolutionary model, and comparative genomic analyses of 205 marine vertebrates, we show that ecological interactions with modern cetaceans coincided with the evolution of endothermy in ray-finned fishes during the Eocene-Miocene. This result is supported by evidence of temporal and geographical overlap between cetaceans and endothermic fish lineages in the fossil record, as well as correlations between cetacean diversification and the origin of endothermy in fishes. Phylogenetic comparative analyses identified correlations between endothermy, large body sizes, and specialized swimming modes while challenging diet specialization and depth range expansion hypotheses. Comparative genomic analyses identified several genes under selection in endothermic lineages, including carnmt1 (involved in fatty acid metabolism) and dcaf6 (associated with development). Our findings advance the understanding of how ecological interactions and genomic factors shape key adaptations.

Incompatibility between two major innovations shaped the diversification of fish feeding mechanisms

2025-06-24

Nick Peoples , Michalis Mihalitsis , Peter C. Wainwright | PLoS Biology

Innovations often shape the trajectory of macroevolution, yet their effects are usually considered independently, thus ignoring the functional and evolutionary interactions between them. Two innovations that have underpinned the ecological … Innovations often shape the trajectory of macroevolution, yet their effects are usually considered independently, thus ignoring the functional and evolutionary interactions between them. Two innovations that have underpinned the ecological and evolutionary success of ray-finned fishes (Actinopterygii) are large teeth and highly protrusible jaws, which independently expanded the diversity of prey capture strategies. Here, we explore the functional relationship between these innovations across actinopterygians using high-speed videography and phylogenetic comparative methods. We find that these two innovations are functionally and evolutionarily incompatible because there is an overarching tradeoff between jaw protrusion and tooth size. Having large teeth decreases the kinematic diversity of prey capture by restricting species to overtake prey predominantly by swimming, while highly protrusible jaws are only found in species with small teeth. The space within tooth-bearing bones may impose this constraint, by limiting the maximum tooth size of species with gracile jaws adapted for high mobility and jaw protrusion. Nevertheless, some species break this constraint on tooth size through novel adaptations that accommodate exceptionally large teeth, unlocking new feeding modes which may have expanded the nature of aquatic feeding and influenced the ecosystems themselves. Although both high jaw protrusion and large teeth separately expanded prey capture strategies in fishes, they are generally not found in combination and are evolutionarily incompatible.

Ficha de Aellopos titan

2025-06-24

Felipe Wanderley Amorim , Alexandre Soares , Amabílio José Aires de Camargo +3 more | Datasets - Sistema SALVE - ICMBio

Opportunities for science in touristic shark feeding aggregations – A review

2025-06-24

Jan Bierwirth , Thomas Vignaud , Clémentine Séguigne +1 more | Global Ecology and Conservation

Use of cave habitat by a Philippine Ratsnake, Coelognathus philippinus (Griffin 1909), in Igang Cave, Tabon Cave Complex, Quezon, Palawan, Philippines

2025-06-24

Meljory Corvera , Marvin Jay Sarmiento , Julius Temporas | Reptiles & Amphibians

Globozoospermia

2025-06-24

Laxmi Bhattarai , B Gautam , Bhaktabatsal Raut +1 more | Kathmandu University Medical Journal

Male infertility may be due to low sperm concentration, poor sperm motility, or abnormal morphology. Among the factors involved in male infertility, there is a rare morphology disorder called “Globozoospermia”. … Male infertility may be due to low sperm concentration, poor sperm motility, or abnormal morphology. Among the factors involved in male infertility, there is a rare morphology disorder called “Globozoospermia”. This condition is primarily characterized by the presence of round‐headed spermatozoa, absence of acrosomal cap and cytoskeleton defects around the nucleus. The morphological characteristics of globozoospermia are formed during spermiogenesis. We report here a case of male infertility due to morphological disorder Globozoospermia. Assessment of semen by observing macroscopic and microscopic parameters are not sufficient for sperm analysis. In present case, macroscopic and microscopic assessment was within normal range. Morphological assessment showed 80% of spermatozoa with round head and absence of acrosomal cap. The absence of acrosome makes fertilization impossible since these sperm are unable to bind to the zona pellucida. By using Intracytoplasmic Sperm Injection (ICSI), conception is possible; however, the fertilization rate remains very low.

Diversity of gobioid fishes in the late Middle Miocene of northern Moldova, Eastern Paratethys—part III: dwarf gobies

2025-06-23

Bettina Reichenbacher , А. Ф. Банников | PalZ

Abstract The Middle Miocene (upper Serravallian, Sarmatian sensu latu, Volhynian) deposits at Karpov Yar near Naslavcea, northern Moldova, yield exceptionally preserved fish fossils, often with otoliths in situ. This study, … Abstract The Middle Miocene (upper Serravallian, Sarmatian sensu latu, Volhynian) deposits at Karpov Yar near Naslavcea, northern Moldova, yield exceptionally preserved fish fossils, often with otoliths in situ. This study, the third in our series on goby fossils from Karpov Yar, describes four new dwarf goby species (standard lengths 16–34 mm), including two new genera: † Moldavigobius gloriae sp. nov., † Cryptograciles conicus gen. et sp. nov., † Cryptograciles robustus gen. et sp. nov., and † Alienagobius pygmaeus gen. et sp. nov. A fifth species is left in open nomenclature as † Moldavigobius sp. The new genera share 27 vertebrae (10 abdominal), a D1 with six spines, a D2 with a spine and 9–11 rays, and ctenoid flank scales. Differences include the D1-pterygiophore formula, pelvic- and anal fin ray counts, scale number, and otolith morphology. The phylogenetic analyses suggest that † Moldavigobius spp. could be part of the Aphia lineage (Gobiidae), † Cryptograciles gen. nov. may belong to the Pomatoschistus lineage (Oxudercidae), and † Alienagobius gen. nov. possibly represents a stem member of the Stenogobius lineage, although this is surprising given the tropical biogeography of this lineage and its absence in the fossil record. Morphological similarities across the fossil genera likely reflect adaptations to a cryptobenthic lifestyle in a low-energy, lagoonal environment, while variations in scales and otoliths between species indicate microhabitat specialization. Our findings suggest Karpov Yar was an ecologically dynamic site, providing various microhabitats that allowed for the coexistence of multiple cryptobenthic goby species.

Bathyraja nansei, a new deep-water softnose skate (Rajiformes: Arhynchobatidae) from the Okinawa Trough, southern Japan

2025-06-21

Ryo Misawa , Masato Moteki , Hiromitsu Endo | Ichthyological Research

Articulated specimens provide new insights into the iconic Mesozoic shark genus Sphenodus

2025-06-20

Eduardo Villalobos‐Segura , Manuel Amadori , Sebastian Stumpf +6 more | Journal of Systematic Palaeontology

Transoceanic dispersal and connectivity of a white shark (Carcharodon carcharias) between southern Africa and Southeast Asia

2025-06-19

Dylan T. Irion , Oliver J. D. Jewell , Alison V. Towner +6 more | Wildlife Research

Population connectivity shapes dispersal, genetic structure, and responses to climate change. Understanding these patterns is vital for identifying threats and improving species management strategies. In May 2024, a fisher from … Population connectivity shapes dispersal, genetic structure, and responses to climate change. Understanding these patterns is vital for identifying threats and improving species management strategies. In May 2024, a fisher from Indonesia with a satellite tag in their possession contacted local conservationists from non-profit organisation Project Hiu. The Project Hiu staff contacted Wildlife Computers with the serial number and successfully located the tag owner. Remarkably, the tag was identified as having been attached to a 390 cm total-length (TL) subadult female white shark (Carcharodon carcharias) in May 2012 in South Africa. Through subsequent investigations, including email correspondence and interviews with the fishers, we have determined that in November 2016, a 473 cm TL female shark (misidentified at the time as a longfin mako shark, Isurus paucus) was captured in longline gear off the coast of Indonesia, Southeast Asia. This remarkable sequence of events marks the first documented movement and connectivity of a white shark between South Africa and Southeast Asia (Indonesia). Over the 4.5 years at liberty, the shark grew in length an estimated 83 cm (18.4 cm per year), supporting previous findings on growth rates for the species. This record of events highlighted both the potential for misidentification and trade of threatened and protected shark species and the increasing benefits of close collaboration with local fishers. This newly discovered link expands our understanding of their wide-ranging connectivity among remote regions, advances our knowledge of their biology and behavior, and underscores the importance of ongoing international research and conservation efforts to protect these apex predators and their habitats.

Knowledge drives conservation: Tackling the shark consumption issue in Italy – A case study

2025-06-19

Mario A. Cedrini , Miikka Dal Maso , M. Carola +5 more | Marine Policy

Spatiotemporal trends in abundance and richness of elasmobranchs in Frégate Island, Seychelles

2025-06-18

Maria V. Lourie , Anna Zora , Oriane Servant +7 more | Marine Biology

Abstract Elasmobranch diversity has been poorly investigated within the Seychelles archipelago. The present study aimed to describe the spatial-temporal changes in the species richness and abundance of elasmobranchs on Frégate … Abstract Elasmobranch diversity has been poorly investigated within the Seychelles archipelago. The present study aimed to describe the spatial-temporal changes in the species richness and abundance of elasmobranchs on Frégate Island, Seychelles. Baited Remote Underwater Video Systems (BRUVS) were performed between May 2019 and December 2022. A total of 18 elasmobranch species were observed, comprising nine sharks and nine rays. Most species face extinction risks according to IUCN criteria; 50% are categorized as Vulnerable, 28% as Endangered, and 11% as Critically Endangered. Higher relative abundances were detected for the grey reef shark ( Carcharhinus amblyrhynchos ), followed by the nurse shark ( Nebrius ferrugineus ), short-horned pygmy devil ray ( Mobula kuhlii ), whitetip reef shark ( Triaenodon obesus ), and the critically endangered white-spotted guitarfish ( Rhyncobatus australiae ). While month and year did not affect elasmobranch relative abundance (MaxN), elevated temperatures (~ 30 ºC) significantly reduced elasmobranch MaxN. Moreover, habitat substrate was the best predictor of elasmobranch MaxN. Sharks were often encountered on rock and rubble, while batoids were more likely found on rock and sand. The presence of juvenile tiger sharks was consistent in all sampled years, but with low MaxN values. Our findings highlight the significant conservation concerns for elasmobranch species in the region and emphasize the urgent need for protective measures within the Seychelles Archipelago.

New ichthyofaunal microfossils from the Late Permian at Chaotian, Sichuan, Southwest China

2025-06-18

Jiachun Li , Zuo-Yu Sun , Gilles Cuny +3 more | Swiss Journal of Palaeontology

A seasonal aggregation of juvenile scalloped hammerheads <scp>Sphyrna lewini</scp> along beaches of the <scp>G</scp>old <scp>C</scp>oast, <scp>A</scp>ustralia

2025-06-18

Nicolas Lubitz , Kerryn Doupain , Siobhan Houlihan +1 more | Journal of Fish Biology

Abstract We document a recurring seasonal aggregation of juvenile scalloped hammerhead sharks Sphyrna lewini along the beaches of the Gold Coast, Australia, with notable occurrences at Burleigh Heads and Kirra … Abstract We document a recurring seasonal aggregation of juvenile scalloped hammerhead sharks Sphyrna lewini along the beaches of the Gold Coast, Australia, with notable occurrences at Burleigh Heads and Kirra Reef. The aggregation consists of individuals of varying sizes, which likely suggests the presence of different cohorts, though it remains uncertain whether this area meets the criteria for a nursery habitat. Given the global population declines of S. lewini , its classification as Critically Endangered by the IUCN and its Conservation Dependent status under Australian legislation, we recommend standardised surveys and tracking studies to assess habitat use, seasonality and the potential role of Gold Coast waters as a critical habitat for juvenile S. lewini .

A blacktip's black tip: The reliability of using dorsal‐fin patterns for photo identification of blacktip reef sharks (Carcharhinus melanopterus)

2025-06-18

Laetitia A. M. G. Lionnet , Shamil F. Debaere , Hugo Heuls +3 more | Journal of Fish Biology

Abstract Photo identification (photo ID) has increasingly become a valuable technique serving not only to identify individual animals but also to monitor populations, track migration patterns and assess wildlife health, … Abstract Photo identification (photo ID) has increasingly become a valuable technique serving not only to identify individual animals but also to monitor populations, track migration patterns and assess wildlife health, among others uses. Various species of sharks are amenable to photo ID, among which the blacktip reef shark ( Carcharhinus melanopterus ) is a particularly suitable subject. Their distinctive pigmentation and dorsal‐fin patterns serve as potential key identifying features. This study focuses on the variation in dorsal‐fin patterns among individual neonatal and juvenile C. melanopterus around Moorea, French Polynesia. We employed a Gower distance matrix to assess dissimilarities in dorsal‐fin patterns and conducted an elliptical Fourier analysis (EFA) to characterize shape variations. The results from the EFA were further summarized using principal component analyses. Additionally, we explored the potential symmetry between the left and right sides of the dorsal fin. To assess the long‐term reliability of using pigmentation patterns for photo ID, dorsal‐fin patterns of recaptured individuals were compared using regressions of log‐transformed dorsal‐fin measurements over log‐transformed pre‐caudal lengths. Recaptures occurred over varying time frames, ranging from as short as 2 weeks to as long as 9 months. The diverse range allowed us to evaluate the temporal stability of dorsal‐fin patterns across different intervals. The analyses revealed that each individual shark's dorsal‐fin pattern is unique, but the left and right sides are asymmetrical. Regarding the analysis of recaptured individuals, the ontogenetic changes in dorsal‐fin size were not significant enough to alter the dorsal‐fin patterns, thus ensuring their temporal stability. The application of photo ID techniques, as demonstrated in this study, underscores its indispensable role in conservation strategies, promoting a deeper understanding of elasmobranch species.

Ficha de Glomeridesmus spelaeus

2025-06-17

Luiz Felipe Moretti Iniesta , Amazonas Chagas , Jéssica Scaglione Gallo +4 more | Datasets - Sistema SALVE - ICMBio

Ficha de Xiphorhynchus guttatoides gracilirostris

2025-06-17

Helder Farias Pereira de Araújo , Alexandre M. Fernandes , Antônio Emanuel Barreto Alves de Sousa +7 more | Datasets - Sistema SALVE - ICMBio

Sharks may use an unexpected organ to fight microbial invaders

2025-06-17

| AAAS Articles DO Group

First record of the Indo-West Pacific spotted scat Scatophagus argus (Acanthuriformes, Scatophagidae) from the Canary Islands (East-Central Atlantic).

2025-06-16

Fernando Espino , José A. González | Vieraea Folia scientiarum biologicarum canariensium

The Indo-West Pacific spotted scat Scatophagus argus (Acanthuriformes, Scatophagidae) is reported for the first time in the Canary Islands (eastern-central Atlantic). This record is based on the sighting of an … The Indo-West Pacific spotted scat Scatophagus argus (Acanthuriformes, Scatophagidae) is reported for the first time in the Canary Islands (eastern-central Atlantic). This record is based on the sighting of an individual in 2017, which was photographed swimming in shallow waters off the northeastern coast of Gran Canaria, along a route with heavy maritime traffic. In addition to ballast water and organisms transported by oil platforms, the specimen may have been released from an aquarium. No further sightings or captures of this species have been recorded.

An invisible trade in imperiled guitarfishes

2025-06-16

Bryan L. Huerta‐Beltrán , J. Marcus Drymon , Amanda E. Jargowsky +2 more | Conservation Biology

Marine fishes exhibit exceptional variation in biofluorescent emission spectra

2025-06-16

Emily Carr , Mason A Thurman , Rene P. Martin +2 more | PLoS ONE

Biofluorescence is a phylogenetically widespread phenomenon among marine fishes, yet the phenotypic diversity in fluorescent emission wavelengths (e.g., green, red) remains poorly studied across the broad diversity of marine teleosts. … Biofluorescence is a phylogenetically widespread phenomenon among marine fishes, yet the phenotypic diversity in fluorescent emission wavelengths (e.g., green, red) remains poorly studied across the broad diversity of marine teleosts. In this study we investigate the fluorescent emission spectra from a diverse array of 18 teleost families and record fluorescent emission peaks over multiple body regions. Our results show that fluorescent emission spectra are remarkably diverse among teleost families, as well as within genera. Fluorescent emissions also vary across different body regions within some individuals. We show that members of the families Gobiidae, Oxudercidae, and Bothidae exhibit at least six distinct, non-overlapping fluorescent emission peaks. Nine of the 18 families examined in this study were found to have at least four distinct and non-overlapping fluorescent emission peaks. Further, we find that several families exhibit multiple discrete emission peaks for a single fluorescent color (i.e., wavelength range), including multiple distinct peaks within the green and red portions of the spectrum. The interplay between different fluorescent emission wavelengths and notable variation in the distribution of fluorescence on the body could allow for a wide array of fluorescent patterns to be produced by an individual or among closely related species. Our results reveal far more diversity in both fluorescent emission wavelengths (colors) and in the distribution of fluorescent molecules across the body than had previously been reported in the literature. We characterize this novel variation in biofluorescent emissions across an array of teleost families and discuss the potential implications of this exceptional phenotypic variability.

A new species of eight-gilled hagfish (Myxinidae: Eptatretus) off Kerala, Western Indian Ocean

2025-06-16

Ian C. George , Bineesh KK , Agnita Sharon E +3 more | Species

Whale shark <scp>Rhincodon typus</scp> foraging on small schooling fish in the northern Mexican Caribbean

2025-06-16

Natalí Cárdenas‐Palomo , Emanuel Mimila‐Herrera , Iván Velázquez–Abunader | Journal of Fish Biology

Abstract The whale shark ( Rhincodon typus ) aggregates in the Mexican Caribbean from May to September to feed on mixed zooplankton patches and fish spawn. For the first time … Abstract The whale shark ( Rhincodon typus ) aggregates in the Mexican Caribbean from May to September to feed on mixed zooplankton patches and fish spawn. For the first time in this area, we present evidence of observations of whale sharks feeding on schools of small fish, two in 2017 (10 individuals per flight) and one in 2024 (19 individuals). This fact shows that there is another food source for the species at this site, which may be used as an alternative to meet their energy demands when zooplankton is scarce.

First record of Brotula barbata (Ophidiiformes, Brotulidae) from the Canary Islands: A new Northern limit in the Eastern Atlantic.

2025-06-16

José A. González , Fernando Espino | Vieraea Folia scientiarum biologicarum canariensium

The amphi-Atlantic species Brotula barbata (Bloch & Schneider, 1801) (Ophidiiformes, Brotulidae) is reported for the first time in the Canary Islands (northeastern Atlantic). This finding marks a new northern limit … The amphi-Atlantic species Brotula barbata (Bloch & Schneider, 1801) (Ophidiiformes, Brotulidae) is reported for the first time in the Canary Islands (northeastern Atlantic). This finding marks a new northern limit for its distribution in the eastern Atlantic. This study also contributes to the knowledge of the species’ morphological characteristics.

New records of fishes from the Coral Sea Marine Park, Australia

2025-06-16

Yi‐Kai Tea , Tiffany L. Sih , Fenton Walsh +7 more | Coral Reefs

Abstract With an area covering just under 1 million km 2 , Australia’s Coral Sea Marine Park (CSMP) is among the largest marine protected areas globally. Yet, the demersal deep-reef … Abstract With an area covering just under 1 million km 2 , Australia’s Coral Sea Marine Park (CSMP) is among the largest marine protected areas globally. Yet, the demersal deep-reef fish fauna of the CSMP remains poorly described, due in part to its remote location, as well as its sheer size, much of which is inaccessible below conventional SCUBA diving depths. Recent remotely operated vehicle (ROV) explorations conducted by the Schmidt Ocean Institute provided an opportunity to explore the benthic ichthyofauna of deep mesophotic and rariphotic coral ecosystems. Contributions to the deep, demersal ichthyofauna of Australia’s CSMP are herein supplemented with an integrative dataset consisting of ROV imagery and specimen vouchers. Sixty-two new records of fishes from 26 families are reported from the CSMP. Of these, 45 are new Australian records, one of which is also a new family record for Australia. Four species are new records for the Southern Hemisphere, and 21 species are potentially new to science. We report new voucher material for 29 species, including several species previously identified as new for the CSMP with no voucher specimens.

Ecology, conservation, and future perspective of walking sharks (Hemiscyllium spp.) in Indonesia

2025-06-16

Fahmi Fahmi , Yanuariska Putra , Selvia Oktaviyani +3 more | Pacific Conservation Biology

Context Walking sharks (Hemiscyllium spp.), native to the Indo–Pacific region, are small, benthic elasmobranchs that exhibit unique fin-assisted locomotion to ‘walk’ along the ocean floor using their fins. Although those … Context Walking sharks (Hemiscyllium spp.), native to the Indo–Pacific region, are small, benthic elasmobranchs that exhibit unique fin-assisted locomotion to ‘walk’ along the ocean floor using their fins. Although those species are not primary fishery targets, they face significant threats from fishing, habitat degradation, and exploitation for the international aquarium trade. Conservation efforts have advanced, notably with the full legal protection of all Hemiscyllium species under Indonesia’s Ministerial Decree in 2023. Methods This review examines the ecology, fishery utilisation, and conservation status of Hemiscyllium species, focusing on Hemiscyllium freycineti and Hemiscyllium halmahera in Indonesia. Information were provided from literature reviews, government regulations and policies, interviews, and field observations. Key results Raising public awareness on the protection status of walking sharks are needed in several locations where exploitation is taking place. The development of walking shark tourism can be one of the non-extractive utilisation efforts that may gain economic benefits for local communities. In addition, captive breeding development program can be a solution for population restoration and fulfilling the need for marine ornamental fish industry. Conclusion Efforts to protect walking sharks must encompass comprehensive management strategies that involve local communities, government regulations, and international cooperation. The expansion of Marine Protected Areas (MPAs), habitat restoration, and developing captive breeding programs in Indonesia are essential to the sustainability of the walking shark populations. Implications This paper advocates for integrated conservation strategies, including habitat rehabilitation, adaptive fisheries management, and community-based ecotourism, to ensure the long-term viability of walking shark populations in Indonesia.

Predictions of southern migration timing in coastal sharks under future ocean warming

2025-06-14

Maria Manz , Oliver N. Shipley , Robert M. Cerrato +7 more | Conservation Biology

Abstract Projected redistribution of marine species due to ocean warming may undermine current conservation efforts. Yet, there have been few studies on how ocean warming may alter migration timing. Across … Abstract Projected redistribution of marine species due to ocean warming may undermine current conservation efforts. Yet, there have been few studies on how ocean warming may alter migration timing. Across 5 years of acoustic telemetry data (2018–2022), we determined environmental drivers of southward migration timing for 6 migratory shark species from summer habitats in the Northwest Atlantic Ocean. We then forecasted how migratory timing from 3 regions, between the New England shelf and Mid‐Atlantic Bight, would respond under future sea surface temperatures (SSTs). Photoperiod and SST were strong predictors of southern migration in sharks, but the strength of these effects varied latitudinally. Overall, we found delayed departure dates from summer habitats under future elevated SSTs, indicating prolonged residency in northern habitats (median = ∼12 days). Sandbar sharks ( Carcharhinus plumbeus ) exhibited the largest delay in the onset of southern migrations (median = 29 days), whereas sand tiger sharks ( Carcharias taurus ) and white sharks ( Carcharodon carcharias ) exhibited the smallest delay (median = 1 day). Delays in migration timing of coastal shark species may alter local ecosystem dynamics and challenge current management strategies. These findings illustrate the utility of collaborative data‐sharing networks to expand understanding of broadscale animal movements and contribute to effective species management under a changing climate.

Experience of spiny dogfish Squalus acanthias interactions with aquaculture installations in Norway

2025-06-13

Pradeep Lal , Antonie Oosterkamp , Shaw Bamber +1 more | Frontiers in Aquaculture

The spiny dogfish ( Squalus acanthias ) is a common shark species found along the Norwegian coast. This coast is also utilized for salmon farming, and farmers report incidents of … The spiny dogfish ( Squalus acanthias ) is a common shark species found along the Norwegian coast. This coast is also utilized for salmon farming, and farmers report incidents of spiny dogfish biting through nets and often entering the fish cages. This causes breaches that allow farmed salmon to escape leading to both financial loss and an ecological risk to endangered wild salmon populations. Unfortunately, the extent and impact of such incidents has not been studied. Here, we conducted survey-based research among the fish farms, unravelling geographical distribution, cause, frequency and impact of spiny dogfish incidents in Norway. We quantified the experiences of fish farmers regarding spiny dogfish incidents and found that most incidents were localized in southern and western Norway during autumn and winter periods. Most spiny dogfish attacks are in groups, primarily targeting the base of fish cages and often attacking the same cage multiple times. These attacks are mostly associated with the presence of dead fish in the cages; the timely removal of carcasses largely mitigates these incidents. However, considering the impact of escapees on wild fish populations, combined with periods of elevated fish mortality within the cages when it is difficult to rapidly remove dead fish, multiple mitigation approaches are necessary. Moreover, spiny dogfish is listed as a vulnerable species and an effective measure in keeping them away from sea cages will reduce their mortality associated with fish farms. Hence, we also discuss suitable shark-deterrents as mitigating measures without harming either the spiny dogfish or the farmed fish.

A new seal from the Late Miocene of the Eastern Paratethys highlights the past regional diversity of true seals (Phocidae)

2025-06-12

Pavlo Otriazhyi , Theodor Obadă , Oleksandr Kovalchuk +2 more | Swiss Journal of Palaeontology

A new barracudina (Aulopiformes, Paralepididae, Stemonosudis) from Somalia, with additional records of S. siliquiventer from the Caribbean Sea

2025-06-12

HSUAN–CHING HO , Tsung‐Yu Yang | ZooKeys

A new species, Stemonosudis adenensis sp. nov. , of slender barracudina is described based on a specimen collected off Somalia, Western Indian Ocean. The new species differs from its congeners … A new species, Stemonosudis adenensis sp. nov. , of slender barracudina is described based on a specimen collected off Somalia, Western Indian Ocean. The new species differs from its congeners by having a uniformly brown body, without distinct black patches; nostrils slightly before the posterior end of the maxilla; anus above the tip of the appressed pelvic fin; lateral-line scales: prepelvic 39, predorsal 48, preanal 59, total 81; vertebrae: prepelvic 38, prehaemal 42, predorsal 46, preanal 59, caudal 53, and total 95; and total gill rakers 68. Additional records of Stemonosudis siliquiventer Post, 1970 from the Caribbean Sea are also provided.

Pyconodont fishes from the Eocene of Jaisalmer Basin, Rajasthan, Western India

2025-06-11

Krishna Kumar , BINDHYACHAL PANDEY , Seema Kulshreshtha +4 more | Journal of the Palaeontological Society of India

Pycnodus was among the fish genera that successfully survived the Cretaceous-Palaeogene (K-Pg) mass extinction event. It was the longest existing and most adaptable taxon within the entire group of pycnodonts. … Pycnodus was among the fish genera that successfully survived the Cretaceous-Palaeogene (K-Pg) mass extinction event. It was the longest existing and most adaptable taxon within the entire group of pycnodonts. The present study highlights the finding of pycnodont remains (prearticular dental plate and isolated teeth) from the Khuiala Formation (Early Eocene, Ypresian) and the Bandah Formation (Middle Eocene, Bartonian), Jaisalmer Basin, Rajasthan. The specimens from the Khuiala Formation are assigned to Pycnodus toliapicus , and those from the Bandah Formation are assigned to Pycnodus sp. The record of Pycnodus toliapicus is particularly significant as it is the only species from India based on a dental plate. It signifies the presence of pycnodonts in the seas east of the Tethys just before they got completely extinct worldwide.

Distribution, Relative Abundance, and Biology of the Deep-Water Dusky-Purple Skate Bathyraja matsubarai (Arhynchobatidae)

2025-06-10

А. М. Орлов , Igor V. Volvenko , Igor V. Grigorov | Journal of Ichthyology

Novel risk assessment framework to compare shark‐bite mitigation strategies

2025-06-04

Michelle Henriksen , Adam Barnett , Paul A. Butcher +7 more | People and Nature

Abstract Human–wildlife conflicts (HWCs) are increasing globally and are some of the most pervasive problems for the conservation of terrestrial and marine species. Stakeholders often hold different values and concerns … Abstract Human–wildlife conflicts (HWCs) are increasing globally and are some of the most pervasive problems for the conservation of terrestrial and marine species. Stakeholders often hold different values and concerns surrounding HWCs, and understanding these values and their relative importance among stakeholders allows for more effective decision‐making. We developed a multi‐objective decision analysis framework to compare and assist in determining preferred mitigation measures to reduce HWCs. We illustrate how this framework can be used to identify appropriate mitigation measures to reduce the risk of shark bites, which have been increasing worldwide and have led to ongoing controversy and debate between governments and other stakeholders. We combined expert assessment of shark‐bite mitigation measures against socio‐economic and environmental criteria, while accounting for subjective ranking of the importance of these performance criteria across stakeholders. Our flexible framework was tested to compare 15 mitigation measures for the Gold Coast region of Queensland, Australia, using 12 performance criteria. Results reiterated the societal shift towards non‐lethal measures and highlighted which mitigation measures or performance criteria lacked information, helping to identify knowledge gaps and research needs. The flexibility of our framework makes it applicable to a broad range of contexts and HWCs and allows the incorporation of location‐specific requirements and views that may vary between stakeholders. Read the free Plain Language Summary for this article on the Journal blog.