Little is known about the Chondrichthyes fauna of the state of Espírito Santo, southeastern Brazil, notably on the species composition, distribution, and biology. Historically, only a few studies have focused on these issues. Basic taxonomy is one of the main tools employed in cataloguing, organizing, and initiating other, more specific, assessments regarding regional diversity. In this context, this study presents the most comprehensive list of shark and ray species occurring in the state of Espírito Santo to date. The compiled data were obtained from specimens deposited in ichthyological collections, literature reviews, and samplings conducted at fisheries landings and onboard commercial fleet vessels. The findings indicate 79 species, comprising 51 sharks and 28 rays. A total of 53.2% of threatened Brazilian marine elasmobranch species occur in the area, indicating the importance of carrying out local studies focusing on this group. A first record for the Brazilian large-eyed stingray, Hypanus marianae, was also observed for the state, increasing the southern limit of the species known distribution, previously considered restricted to the North and Northeast coasts.

Sharks are scarce in much of the Caribbean due to widespread depletion. Trinidad and Tobago, in the southern Caribbean, is a shark meat consumer and international exporter of dried shark fins. Despite limited fisheries management there is a small Marine Protected Area (MPA; 7 km2) in urbanised southwest Tobago, but its effect on sharks and rays (elasmobranchs) is unknown. The rural northeast is a recently designated UNESCO Man and the Biosphere Reserve with a significant marine component and plans for a large MPA, but no baseline data for elasmobranchs exist. Given the local importance of elasmobranchs and a newly drafted Sustainable Shark and Ray Management Plan, we used baited remote underwater video stations within a 40 m depth contour at 270 randomly generated points around Tobago to: (i) establish a baseline of species richness and relative abundance, (ii) investigate the influence of season, habitat relief, depth and water temperature on relative abundance, and (iii) investigate spatial variation in relative abundance. Caribbean reef sharks, nurse sharks, and southern stingrays were observed at all sites, the latter two more frequently in the urbanised southwest. Shark diversity was unexpectedly high in the northeast, driven by rarer species (sharpnose, smoothhound, tiger, scalloped hammerhead, great hammerhead) only observed there. Habitat relief, depth and season likely influence relative abundance of elasmobranchs around Tobago, but research is needed to elucidate species-level effects. Shark species richness in northeast Tobago is high for the Caribbean, warranting research attention, while the larger MPA presents an opportunity to strengthen elasmobranch management.

This article examines the dog-like aspects and associations of two marine monsters of Graeco-Roman antiquity: Scylla and the κῆτος. Both harbour recognizably canine features in their depictions in ancient art, as well as being referenced as dogs or possessing dog-like attributes in ancient texts. The article argues that such distinctly canine elements are related to, and probably an extension of, the conceptualization of certain marine animals, most prominently sharks, as ‘sea dogs’. Accordingly, we should understand these two sea monsters and the sea dogs as being interrelated in the ancient imagination. Such a canine resonance to certain sea creatures offers a valuable insight into the Graeco-Roman imagination of the marine element as being the abode of creatures reminiscent of terrestrial dogs.

The objective of this paper was to characterize bycatch in an experimental fishery for Patagonian toothfish in Ecuador during 2017–2021. Diversity was analysed using Shannon, Margalef, Simpson, and Dominance indices. Bycatch representativity was calculated as the difference percentage between the target catch and non-target, in weight. The bycatch comprised 51 taxa and was composed primarily of fish. In addition, 12 species of pelagic habits (i.e. fishes and sharks) were also captured during the deployment/retrieval of fishing gear. The most frequent species (by number of individuals) were chimaeras (Hydrolagus melanophasma), grenadiers (Antimora rostrata, Coryphaenoides delsolari, and Coryphaenoides armatus), and sharks (Etmopterus granulosus and Centroscymnus owstonii). The diversity was medium low, according to the Shannon indices (0.5–1.8), with a negative trend for dominance and a positive trend for equitability.

The nematode Mooleptus rabuka is recorded in the digestive tract of catshark Apristurus fedorovi caught at the Imperial Ridge (Pacific Ocean). Important morphological features such as the number of cephalic and caudal papillae, the position of amphids and the shape of the gubernaculum are detailed in this parasite species. According to the phylogenetic analyses based on the 18S ribosomal RNA gene sequences, M. rabuka forms a lineage, Mooleptinae nom. nov., which is close to the gnathostomatid genus Echinocephalus (maximum likelihood analysis), or else forms a polytomy with this genus and the lineages of Anguillicola + Spiroxys and Tanqua + ‘Linstowinema’ sp. (Bayesian inference analysis). Overall, our findings do not support the monophyly of the Gnathostomatidae. We elevate spiroxyines to the family status, Spiroxyidae stat. nov., and temporarily consider the Gnathostomatidae to include the following subfamilies: Ancyracanthinae Yorke & Maplestone, 1926, Gnathostomatinae Railliet, 1895 sensu lato and Mooleptinae nom. nov. The name Mooleptinae nom. nov. is suggested instead of the Metaleptinae Moravec & Nagasawa, 2000, which is based on a preoccupied generic name Metaleptus Machida, Ogawa & Okiyama, 1982.

Considerable global attention has focused on the plight of sharks and the implications for ocean health. Scientists point to the importance of sharks for healthy ecosystems and the consequences of their disproportionate removal; yet legal and management responses vary considerably. In some states, negative human-shark interactions have led to shark culls and swimming bans, and have prompted public fears about future activities that might attract species closer to coasts and communities. In other countries, sharks are respected, conserved and utilized only as a non-consumptive marine-based tourism resource. This article argues that culture plays an important role in the variety of legal responses to the conservation and management of sharks. By examining the development of shark sanctuaries across the Indian and Pacific Ocean island states, this analysis highlights the legal approaches taken, and the varying socio-cultural values that have influenced these responses. Understanding the role of culture will remain important as these laws mature, because it may affect implementation, compliance, and ultimately the achievement of conservation outcomes.

Representations and remains of sharks are found in Mesoamerican art and archaeology from the first millennium BC onwards. They appear at coastal sites, but also remarkably far inland, hundreds of kilometres from the waters where they were sighted or hunted. For the Maya of the interior of the Yucatán Peninsula, encounters with live sharks would have been an exceedingly rare occurrence. Yet the animals arrived inland in piecemeal fashion—as chunks of meat and sets of teeth—and via stories. By following the procurement, transportation, representation and ritual use of sharks from the sea to the jungle, the author shows how the ancient Maya drew on both evidence and myth to imagine and explain these unfamiliar marine creatures.

Chondrichthyans are usually caught incidentally in fisheries for species of high commercial value and then discarded on board or landed as by-products. On the coast of Chubut province and adjacent waters (43°00′S–44°56′S) a bottom trawl fishery has developed targeted at the Patagonian shrimp (Pleoticus muelleri) and common hake (Merluccius hubbsi). Since 2005, this fishery has been monitored by the On-board Observers Program of Chubut province (POBCh). With the aim of advancing towards an ecosystem approach, POBCh not only collects information about target species but also about all the species caught by the trawl nets of the province fisheries. From the information collected by this programme it was possible to identify and record the chondrichthyan species vulnerable to the fishing gear used by the coastal fleet that operates from Puerto Rawson. The composition of the fleet catch was characterized according to the target species during the 2005–2014 period. In the analysis of 3786 hauls, 23 species of chondrichthyans (seven species of sharks, 15 species of batoids and a single species of Holocephali) were identified. Seven species showed a frequency of occurrence greater than 10% (Callorhinchus callorynchus, Discopyge tschudii, Mustelus schmitti, Sympterygia bonapartii, Psammobatis normani, Squalus acanthias and Zearaja chilensis). Species spatial distribution was evaluated and five areas of species assemblages were established. Besides the aspects related to bycatch, these analyses have contributed to the knowledge of the chondrichthyan biodiversity in the provincial coast where the fleet operates, a region with incomplete and mostly dispersed and outdated information.

Shark bite marks on mosasaur bones abound in the fossil record. Here we review examples from Kansas (USA) and the Maastrichtian type area (SE Netherlands, NE Belgium), and discuss whether they represent scavenging and/or predation. Some bite marks are most likely the result of scavenging. On the other hand, evidence of healing and the presence of a shark tooth in an infected abscess confirm that sharks also actively hunted living mosasaurs.

Occupying the upper levels of trophic webs and thus regulating prey at lower levels, sharks play an important role in the trophic structure and energy dynamics of marine ecosystems. In recent years, the removal of these individuals from upper trophic levels as a result of overfishing has negatively affected ecosystems. We analysed the diet of blue sharks (Prionace glauca) caught off the west coast of Baja California Sur, Mexico, during the months of February–June in 2001, 2005 and 2006. We employed both stomach content and stable isotope analyses as each method provides distinct yet important information regarding the role of blue sharks in marine food webs, allowing us to estimate the relative contribution of different prey items to this predator's diet. Of the 368 stomachs analysed, 210 contained food (57%) and 158 (43%) were empty. Based on stomach contents and the index of relative importance (IRI), the pelagic red crab (Pleuroncodes planipes) was the most important prey, followed by the squids Gonatus californiensis (34.1%) and Ancistrocheirus lesueurii (10.4%). The mean (±SD) values for δ15N (16.48 ± 0.94‰) and δ13C (−18.48 ± 0.63‰) suggest that blue sharks prefer feeding in oceanic waters. The trophic level based on stomach content analysis was 4.05, while that based on the stable isotope analysis was 3.8, making blue sharks top consumers in the marine ecosystem of Baja California Sur, Mexico.

The oldest records on the sharks of the Sea of Marmara are limited to a few notes on two great white sharks, Carcharodon carcharias, which were caught in the southern part of the Bosphorus Strait by the bluefin tuna (Thunnus thynnus) handliners in February and November of 1881 (Fergusson, 1996: Appendix 3, 345). A review of the shark-specific or general ichthyology studies of the Sea of Marmara, as well as of the daily newspapers published since the beginning of 1900s, providing information on the capture of sharks in Marmaric waters, revealed the historical and contemporary occurrence of 21 shark species in the Sea of Marmara. The contemporary occurrence of 13 of the 21 species in the Sea of Marmara has been confirmed by recent studies and fishery records. Recent studies showed that the fish fauna of the Sea of Marmara comprises 235 species, 13 of which are shark species, with the confirmed contemporary occurrences of sharks representing 5.53% of the total ichthyofauna.

Our current knowledge on the carcharhinid sharks occurring in Turkey's seas comprises rudimentary data. Recently discovered photographic evidence suggests that Carcharhinus spp. have been present in the Sea of Marmara since the 1950s. This evidence also extends the known historical distributional range of Carcharhinus spp. into Marmaric waters, a northern extension of the Mediterranean basin. The results of previous and recent ichthyological inventories of the Sea of Marmara suggest that, currently, no species of the Carcharhinidae family occur in Marmaric waters. Further studies could provide an answer to the question: do any species of the Carcharhinidae family inhabit the Sea of Marmara?

This study furthers understanding of cestode infections in a marine environment through time and space by following seasonal fluctuations in infection parameters of three cestode species (Gilquinia squali, Trilocularia gracilis and Phyllobothrium squali) parasitizing spiny dogfish (Squalus acanthias) in the northwest Atlantic and comparing them to work previously published from the northeast Atlantic on T. gracilis. For each cestode species, host size, season and presence of the other cestode species were analysed using generalized linear models to determine if they were good predictors of prevalence and intensity. Infection parameters differed across season for the three cestode species. However, within T. gracilis seasonal trends were found to be remarkably similar on both sides of the Atlantic, differing only in a somewhat delayed decline in prevalence in the northwest Atlantic. The differences seen in infection measures across cestode species likely reflect the unique life history strategies of different parasite species. While general trends appear to be maintained across disparate localities, variation seen is likely due to differences in accessibility to intermediate hosts and host diet across sites. The knowledge gained from understanding cestode infections in the vast ocean environment allows us to speculate about the factors driving fluctuations in parasite infections in elasmobranchs.

A low-cost and non-invasive survey technique focused on pelagic sharks was evaluated during an ecotourism cruise on two Sudanese reefs, Angarosh and Sha'ab Rumi, in the Southern Red Sea. The research technology was based on a set of small, underwater video recording cameras and a pair of laser pointers. Video footage provided insight into shark biodiversity on the two reefs, detecting five species, Alopias vulpinus, Sphyrna lewini, Triaenodon obesus, Carcharhinus amblyrhynchos and Galeocerdo cuvier, during 15.8 h of video recording. These recordings also provided preliminary information on aggregations of S. lewini. The laser pointers were used to measure the size of sharks, providing seven total length (TL) measurements for S. lewini (N = 2) and C. amblyrhynchos (N = 5), confirming the possibility of easily obtaining size parameters using this tool. These low-cost and user-friendly instruments provide ecotourism divers with an opportunity to become involved in marine research projects.

The range of the sicklefin lemon shark (Negaprion acutidens) is expanded to include Palmyra Atoll, in the Northern Line Islands, central Pacific. Despite the fact that researchers have been studying reef and lagoon flat habitats of the Atoll since 2003, lemon sharks were first observed in 2010, suggesting a recent colonization event. To date, only juveniles and sub-adult sharks have been observed.

The Pacific sharpnose shark Rhizoprionodon longurio is caught seasonally by inshore artisanal fisheries in the Mexican Pacific. Our study focuses on the feeding ecology of this shark species in the southern Gulf of California. The prey species obtained from stomach contents were identified and quantified, and variations between sexes and maturity stages were determined. A total of 98 stomachs were analysed during two periods (2000–2001 and 2003–2004); 64% of stomachs contained food. The trophic spectrum was composed of four cephalopod species, three crustacean species, and 13 pelagic and benthic fish species. According to the index of relative importance (%IRI), the fish Echiophis brunneus (IRI = 14.4%), Opisthopterus dovii (IRI = 12.2%) and Scomber japonicus (IRI = 9.6%) were the main prey items. Based on diversity values, IRI values and diet breadth, R. longurio is an opportunistic predator. The trophic position of R. longurio was above four in all categories, which indicates that this shark is a tertiary consumer.

Hooking (or “at-haulback”) fishing mortality was analysed in elasmobranchs captured byPortuguese longliners targeting swordfish in the Atlantic Ocean. Information was collectedby on-board fishery observers who monitored 834 longline fishing sets between August 2008and December 2011, and recorded information on 36 067 elasmobranch specimens from 21different taxa. The hooking mortality proportions were species-specific, with some specieshaving relatively high percentages of live specimens at time of haulback (e.g., blueshark, crocodile shark, pelagic stingray, manta, devil and eagle rays), while others hadhigher percentages of dead specimens (e.g., smooth hammerhead, silky shark, bigeyethresher). For the most captured species (Prionace glauca, Pseudocarchariaskamoharai, Isurus oxyrinchus and Alopias superciliosus),logistic generalized linear models (GLMs) were carried out to compare the mortality ratesbetween sexes, specimen sizes and the regions of operation of the fleet. The sex-specificproportions of hooking mortality were significantly different for blue and crocodilesharks, with the males of both species having higher proportions of hooking mortality thanthe females. Specimen size was significant for predicting the hooking mortality for blueand shortfin mako sharks: in both cases, the larger specimens had lower odds of dying dueto the fishing process. There were differences in the hooking mortality depending on theregion of operation of the fleet, but those differences were also species-specific. Forblue and crocodile sharks, the hooking mortality was higher in the Equatorial and southernAtlantic areas (when compared to the NE Atlantic region), while the opposite was observedfor the shortfin mako, with lower mortality rates in the NE tropical area compared withthe other regions. The results presented in this paper can be integrated into futureecological risk assessment analysis for pelagic elasmobranchs. Furthermore, the newinformation can be used to evaluate the impact of recent recommendations prohibiting theretention of some vulnerable elasmobranch species.

Elasmobranchs are frequently apex predators in marine ecosystems, and information on their diet is essential for understanding trophic relationships in these systems. The diet of the sicklefin smooth-hound, Mustelus lunulatus, was investigated through analysis of gut contents. The diet was relatively homogeneous and was dominated by crustaceans, consisting mostly of the anomuran crab Munida tenella (percentage of the prey-specific index of relative importance (%PSIRI) = 30.5) and the bigtooth rock crab Cancer amphioetus (%PSIRI = 9.9). Use of cumulative prey curves as a measure of precision indicated that data were sufficient to fully describe the diet of M. lunulatus. Further studies are necessary to fully characterize diet across sexes and successive age-classes.

Uncertainty about reporting rates of tags returned by fishermen has often prevented tagging data from being used in stock assessments. In this study we conduct a meta-analysis to estimate tag reporting rates of commercial tuna fleets by comparing their tag return data with those of the USA longline pelagic observer program. The longline fleets of Venezuela and the USA are estimated to report about 0.8% of tags caught, compared with less than 0.1% for Canadian, Spanish and Japanese longline fleets. For some fleets with sparse return data or for those that do not overlap often with the observer fleet, reporting rate estimates are sensitive to changes in the spatio-temporal resolution over which comparisons are made. Regardless of these sensitivities, the estimated reporting rates are low and there are likely to be large differences in reporting rate between different combinations of flag and gear.

The present study provides a check list of elasmobranchs from the Paraná State coast, southern Brazil. Information from fish collections, literature data, field surveys and personal communications were included. Results indicated that 83 species from seven orders and 28 families were recorded. According to the results 51 species belonging to six orders and 17 families of sharks; and 32 species belonging to one order and eleven families of rays occur in this region. The most species-rich families were Carcharhinidae (14 species) and Arhynchobatidae (eight species).