Abstract At the inception of the ICES Journal of Marine Science, first published in 1926, elasmobranchs were largely peripheral to fisheries science. Beyond a few commercially valuable species such as basking shark and spurdog, knowledge of occurrence, life history, population structure, and trends of the ∼105 elasmobranch species occurring across the ICES area was limited. This is reflected in the fact that the first elasmobranch-focused paper in the Journal was published by Holden and Meadows in 1964. However, as commercial fisheries expanded and population declines and local extirpations were documented in the late 20th century, elasmobranchs gained increasing attention from both commercial and conservation perspectives. The ICES Working Group for Elasmobranch Fishes, established in 2003, pioneered methods for estimating removals and stock status despite significant data limitations. From issuing the first advice sheets for six “stocks” in 2005, the group now provides assessments for 56 stocks—more than any other ICES assessment group. This review traces the evolution of elasmobranch science within ICES, examining advances in data quality, assessment methodologies, and the shifting priorities that have transformed this taxon from a marginal concern to a central focus of marine conservation and fisheries management. Past and present Working Group Chairs provide perspectives on key developments, persistent challenges, and future directions for elasmobranch research and advice.

Skates and rays (Batoidea) play a significant ecological role, contributing to ecosystem services through bioturbation and acting as vital intermediate components of the trophic chain in various aquatic environments. Despite their wide global distribution and ecological importance, batoids receive less attention than their shark relatives, resulting in substantial knowledge gaps that might impede a comprehensive understanding of their conservation status. This review addresses critical aspects of their capture, handling, tagging, and release to provide readers with crucial information needed to perform research on batoids. Protocols for analgesia, anaesthesia, and euthanasia are also discussed, taking into account the ethical and logistical considerations necessary for research involving this group of species. This information can give researchers and ethics committees the knowledge to conduct and approve studies involving batoids, thereby promoting more effective and ethical research practices.

Skates (Rajidae) include species of conservation and commercial importance, but there is limited information regarding their ecologically important habitats, including spawning and nursery areas, in northern European seas. Data on the distribution, relative abundance and length composition of skates were collated from scientific trawl surveys, and based on length-frequency information, length-at-hatching and length-at-maturity, skates were allocated to length-based categories representing early-juvenile stages (EJS) and mid-juvenile stages (MJS). Citizen science data were used to inform on the occurrence of eggcases. The Great Eggcase Hunt (starting in 2003) citizen science recording project collects georeferenced data for elasmobranch eggcases, primarily from around the British Isles. This provided verified species-specific data for a total of 227,407 specimens from 11 skate species. Purse Search Ireland (starting in 2005) provided a further 2491 records of 10 skate species from around Ireland. The most frequently observed skate eggcases were from the genus Raja and occurred around much of the British Isles. The EJS and MJS of such species were observed most frequently in inshore waters. Data for EJS were more limited for Raja microocellata and Raja undulata, indicating that the EJS of these species occur in shallower (<20 m) waters. Juveniles of the genus Leucoraja occurred further offshore. Only the eggcases of Leucoraja naevus were recorded regularly, with the eggcase of Leucoraja fullonica described here. The data collated here provide an overview of skate spawning and nursery areas, thus informing fisheries management and marine spatial planning, including the identification and delineation of Important Shark and Ray Areas (ISRAs).

Pelagic stingray (Pteroplatytrygon violacea) is the only species of stingray (Dasyatidae) that utilizes both pelagic and demersal habitats. It is the main bycatch species in pelagic longline fisheries targeting bluefin tuna (Thunnus thynnus) in the Gulf of Lions. In the Mediterranean Sea, their stock structure, behavioural ecology and movements are unknown. For the first time in the Mediterranean, 17 individuals (39–60 cm disc width) were tagged with pop-up satellite archival transmitting tags using a novel method of tag attachment to investigate horizontal and vertical movements. The tags were attached for between two and 60 days. Between the months of July and October, pelagic stingray occupied a temperature range of 12.5–26.6 °C, and a depth range extending from the surface to 480 m. Monthly trends in catch-per-unit-effort (CPUE) of pelagic stingray peaked in August and decreased by late autumn. Pelagic stingray may aggregate on the continental shelf during summer and move southwards in early autumn, and this movement pattern is considered in relation to the reproductive cycle and overwintering. At-vessel mortality was low, but there was varying evidence of post-release mortality, indicating the need for further work. Future work and options for bycatch mitigation are also discussed.

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements.

Angel sharks (Squatina spp.) are distributed in warm temperate to tropical waters around the world. Many species occur in shelf seas and exhibit seasonal inshore-offshore migrations, moving inshore to give birth. Consequently, there can be high spatial overlap between angel shark populations with fisheries and other human activities. Their dorso-ventrally flattened body shape, large size (most species attain >100 cm total length, LT ) and demersal nature means that they may be taken in a variety of demersal fishing gears from birth. Available data indicate that angel sharks typically have a biennial reproductive cycle, with litter sizes generally <20 and the young born at ca. 20-30 cm. The biological characteristics of angel sharks render them susceptible to overexploitation, as exemplified by the decline of Squatina squatina from many parts of its former range in the North-east Atlantic and Mediterranean Sea. Currently, half of the 22 recognised extant species of angel shark are classed as Threatened on the International Union for Conservation of Nature (IUCN) Red List (with a further three classified as Data Deficient). Given the biological vulnerability of angel sharks, and that many species are data-limited, the current paper provides a review of available biological information and fisheries data pertaining to this family. This article is protected by copyright. All rights reserved.

Despite increased focus on ascertaining the status of elasmobranch fish, the stock units for many species are uncertain. Data from mark-recapture tagging studies undertaken from 1959-2017 were analysed for 13 batoid species. Data were most comprehensive for skates (Rajidae), with 22,374 released and 3342 (14.9%) returned. Most data related to thornback ray Raja clavata, blonde ray R. brachyura and spotted ray R. montagui. Tags were generally returned from areas less than 50 km from their release, and usually from the ICES Division in which they were released. However, straight-line distances travelled of up to 910 km (R. brachyura) and 772 km (R. clavata) were recorded, highlighting that individual skates are capable of longer-distance movements. The maximum time at liberty was 16.6 years (R. clavata). Whilst mark-recapture data indicated that the current stock units used by ICES are broadly appropriate, southward movements of several skate species tagged off Northern Ireland (Division 6.a) to the Irish Sea (Division 7.a) were observed. In contrast, skates tagged in the Irish Sea and Bristol Channel (Division 7.f) generally remained in that area, with only occasional recaptures from Division 6.a.

During the last decade, particular attention has been paid worldwide to the problem of by catch and discards in fisheries. Collaborative research between fishermen and scientists is important to fisheries management. Partnerships with commercial longline fishermen were developed to enable them to participate in two research projects in order to integrate their information, experience and expertise. These programmes, financed by the fishing industry and regional councils were designed to describe the activity of the fisheries, to assess the scale of fishery effects on the various taxa, to study ecology and explore spatial population genetic structure in the western part of the Mediterranean Sea of the blue shark (Prionace glauca) and stingray (Pteroplatytrygon violacea) and finally to propose mitigation measures to reduce impacts on elasmobranches, sea birds and sea turtles. Communication, education, post-implementation monitoring and long-standing collaboration are the key factors to success. This presentation shows the progress realized to date.

International trade in vulnerable marine species is regulated once they are listed in CITES Appendices (the Convention on International Trade in Endangered Species of Wild Fauna and Flora). Parties to the Convention submit proposal(s) 150 days prior to the CITES Conference for voting on the inclusion of new species in Appendices I and II, making a case for why CITES listing criteria are met in each case. Before the vote, Parties receive advice from (a) the Food and Agriculture Organization of the United Nations, (b) the International Union for Conservation of Nature-TRAFFIC and (c) the CITES Secretariat, among others. This paper offers an expert review of listing processes, which are the subject of much debate in fishery and environment-protection communities, looking at two specific cases: silky shark (Carcharhinus falciformis, Carcharhinidae) and bigeye thresher shark (Alopias superciliosus, Alopiidae). The reviewers determine that the evidence made available to voting Parties is substantial, but suffers from non-standard presentation across assessments. The best available data are not always presented or described transparently in relation to CITES criteria. An extension of the assessment period, as well as the opportunity to refute evidence, has been suggested as ways to support more informed and effective decision-making by CITES Parties, whose composition of delegations varies greatly in their experience of marine species management and trade. Experts welcomed a greater coherence of advice between fishery and non-fishery sources in the long term, and proposed a range of suggested improvements for the delivery of information and advice to CITES Parties.

Commercial landings of starry smooth-hound Mustelus asterias in northern European seas are increasing, whilst our knowledge of their ecology, behaviour and population structure remains limited. M. asterias is a widely distributed demersal shark, occupying the waters of the southern North Sea and Irish Sea in the north, to at least the southern Bay of Biscay in the south, and is seasonally abundant in UK waters. There are no species-specific management measures for the northeast Atlantic stock, and the complexity of its population structure is not yet fully understood. To address this issue, we deployed both mark-recapture and electronic tags on M. asterias to gain novel insights into its horizontal and vertical movements. Our data suggest that the habitat use of M. asterias changes on a seasonal basis, with associated changes in geographical distribution, depth utilisation and experienced temperature. We report the first direct evidence of philopatry for this species, and also provide initial evidence of sex-biased dispersal and potential metapopulation-like stock structuring either side of the UK continental shelf. Investigations of finer-scale vertical movements revealed clear diel variation in vertical activity. The illustrated patterns of seasonal space-use and behaviour will provide important information to support the stock assessment process and will help inform any future management options.

The stomach contents of 640 starry smooth-hound Mustelus asterias from the Northeast Atlantic were examined. The diet was comprised primarily of crustaceans, which accounted for 98.8% index of relative importance (IRI); with the two main prey species being hermit crab Pagurus bernhardus (34% IRI) and flying crab Liocarcinus holsatus (15% IRI). Ontogenetic dietary preferences showed that smaller individuals (20-69 cm LT ; n = 283) had a significantly lower diversity of prey than larger individuals (70-124 cm LT ; n = 348); however, 18 prey species were found exclusively in smaller individuals and eight prey taxa were found exclusively in larger individuals. Larger commercially important brachyurans such as edible crab Cancer pagurus and velvet swimming crab Necora puber were more prevalent in the diet of larger individuals. Specimens from the North Sea ecoregion had a lower diversity of prey types for a given sample size than fish from the Celtic Seas ecoregion. Whilst cumulative prey curves did not reach an asymptote, this was primarily due to the high taxonomic resolution utilised and 95% of the diet was described by just seven crustacean taxa. The trophic level (TL) was calculated as 4.34 when species-level prey categories were used. This fine-scale taxonomic resolution resulted in a TL estimate close to a whole level above that estimated using wider taxonomic groupings. This large bias has important methodological implications for TL studies based on categorised prey data, particularly those of predatory fish. This article is protected by copyright. All rights reserved.

Data on the vigour and at-vessel mortality (AVM) of 6798 skates (comprising Raja clavata n = 6295; R. brachyura n = 208; R. undulata n = 185, R. montagui n = 98 and R. microocellata n = 12) captured by commercial fishing vessels in the inshore waters of the southern North Sea and English Channel were recorded. AVM in longline fisheries averaged 0·44% across five vessels (0-1·47%), although skates were usually unhooked manually and did not usually pass through a bait-stripper. AVM in otter trawls averaged 0·76% (0-2·35%), from four vessels fishing with tow durations of <1·5 h (southern North Sea) or 1-4 h (English Channel). No AVM was noted for skates taken as a by-catch in drift trammel nets (soak times <4 h). Anchored tangle nets resulted in an overall AVM of 2·0-2·7%, but increased from 1·47% (13-28 h soak time) to 6·16% (42-53 h soak time). There were significant differences in the vigour of skates between gears, with R. clavata caught by longline and tangle nets in better condition than those captured by otter trawl or drift trammel net. Similarly, R. undulata caught by tangle net were in better condition than those caught by otter trawl. The vigour of R. undulata was also found to be higher than other skate species for both trawl and tangle net. In total, 5283 skates were tagged with Petersen discs and released, with recapture rates for the various combinations of vessel and gear ranging up to 24·8% for R. clavata. Whilst confirming a degree of post-release survival, quantitative estimates of post-release mortality for skates remain unknown.

Florida manatees (Trichechus manatus latirostris) possess an unusual suite of adaptations to accommodate both a fully aquatic lifestyle and an herbivorous diet, including a low metabolic rate and a very limited thermoneutral zone. Their relatively high lower critical temperature of around 20 °C suggests strong sensitivity to cold, thereby limiting their distribution to tropical and subtropical waters. "Cold stress syndrome" affects and kills Florida manatees every year during intense or prolonged cold weather, posing one of the major threats to manatees. However, knowledge regarding manatee thermoregulation is sparse, but essential for effective conservation and management of this threatened species. We measured heat flux in two captive Florida manatees at multiple times of the year, at 41 sites distributed across the entire body surface of each manatee. Heat flux differed significantly between individuals, and among body sites and times of the year. The pectoral flippers and axillae were identified as areas with highest heat exchange. Despite exposure to constant water temperature throughout the year, the manatees in this study had significantly lower heat flux in winter than in summer. We used the measured heat flux values to calculate total heat dissipation in individual manatees. The values estimated this way correspond well with the low metabolic rates estimated in previous studies, confirming the reliability of our novel approach. Our method provides simple and useful options for enhancing manatee welfare by monitoring the animals' thermal state during potentially stressful activities such as during medical treatment, capture restraints and transportation.

Trace metal concentrations in muscle and liver tissues from two offshore species of skate were examined. Concentrations of mercury in muscle of Leucoraja circularis (n = 20; 23-110.5 cm total length, 157-490 m water depth) and L. fullonica (n = 24; 28.5-100 cm total length, 130-426 m water depth) were 0.02-1.8 and 0.04-0.61 mg kg(-1), respectively. Concentrations of both As and Hg increased with total length. Only the largest specimen had a concentration of Hg in muscle > 1.0 mg kg(-1). Data were limited for specimens > 90 cm long, and further studies on contaminants in larger-bodied skates could usefully be undertaken.

There is a need to better understand the survivorship of discarded fishes, both for commercial stocks and species of conservation concern. Within European waters, the landing obligations that are currently being phased in as part of the European Union's reformed common fisheries policy means that an increasing number of fish stocks, with certain exceptions, should not be discarded unless it can be demonstrated that there is a high probability of survival. This study reviews the various approaches that have been used to examine the discard survival of elasmobranchs, both in terms of at-vessel mortality (AVM) and post-release mortality (PRM), with relevant findings summarized for both the main types of fishing gear used and by taxonomic group. Discard survival varies with a range of biological attributes (species, size, sex and mode of gill ventilation) as well as the range of factors associated with capture (e.g. gear type, soak time, catch mass and composition, handling practices and the degree of exposure to air and any associated change in ambient temperature). In general, demersal species with buccal-pump ventilation have a higher survival than obligate ram ventilators. Several studies have indicated that females may have a higher survival than males. Certain taxa (including hammerhead sharks Sphyrna spp. and thresher sharks Alopias spp.) may be particularly prone to higher rates of mortality when caught.

Nature Ecology & Evolution 1, 0170 (2017); published 26 May 2017; corrected 12 June 2017. In the original version of this Article, the European Commission was mistakenly included as an affiliation for Christos D. Maravelias. His contribution to this work was exclusively completed while at the Hellenic Centre for Marine Research.

The reproductive biology and other life-history parameters were investigated for Mustelus asterias in British waters, with specimens caught from both commercial fisheries and research-vessel surveys. In total, 504 specimens [238 males, 24-99 cm total length (LT) and 266 females, 28-124 cm LT] were examined, with further information collected from 238 uterine pups. The lengths at 50% maturity were estimated as 70·4 and 81·9 cm LT for males and females, respectively. Ovarian fecundity ranged from one to 28, and uterine fecundity from four to 20. The number, mass and LT of pups were positively correlated with maternal LT. Full-term pups ranged from 205 to 329 mm LT, and the smallest free-living fish caught was 24 cm LT . Parturition occurred in February in the western English Channel and during June to July in the eastern English Channel and southern North Sea, indicating either protracted spawning or asynchronous parturition for the stock as a whole. The reproductive cycle is thought to extend beyond 1 year. Developmental abnormalities observed included atresia in oocytes, uterine eggs that failed to develop, a partly developed pup and an abnormal male with a single aberrant clasper. Data relating to conversion factors, oocyte numbers and diameter and gonado-somatic and hepato-somatic indices are presented, and the seasonality of the reproductive cycle is discussed.

National and European shark conservation plans aim to manage elasmobranch stocks sustainably. However uncertainties and deficiencies with available data hamper traditional, quantitative assessment methods of stock status to inform those plans, and thus effective management. The International Council for the Exploration of the Sea (ICES) Expert Groups have explored a range of data deficient assessment methods that may be used to support management advice, including Productivity Susceptibility Analysis (PSA). This method was applied to the demersal elasmobranch fauna (21 species) of the Celtic Sea to explore how such approaches could inform the management of skates (Rajidae). This species complex is an important catch component for demersal trawl and gillnet fisheries and is currently managed under a mixed species total allowable catch (TAC). PSAs were conducted on both of these fisheries, by four experts from three countries to introduce independence, and to quantify the range in perceptions of each stock. Confidence scoring of attributes was incorporated and probability distributions generated to model uncertainty in the expert responses to susceptibility attributes. Results showed that three shark species (tope, Galeorhinus galeus; angel shark, Squatina squatina and spurdog, Squalus acanthias) were the most vulnerable species in both fisheries (a consequence of their life history strategy and large size), followed by two skates (otter trawl) and three skates (gillnet). All of these species have some form of restrictive management and, apart from tope, are either currently listed as prohibited species or have a zero TAC in the area. Blonde ray, Raja brachyura was ranked as the next most vulnerable member of the commercially exploited skate complex. This adaptation of the PSA approach enabled skate species of higher and lower risk to be ranked and thus inform where management efforts should be focussed, whilst giving a novel consideration to uncertainty through canvassing expert opinion.

The North-East Atlantic porbeagle (Lamna nasus) population has declined dramatically over the last few decades and is currently classified as 'Critically Endangered'. As long-lived, apex predators, they may be vulnerable to bioaccumulation of contaminants. In this study organohalogen compounds and trace elements were analysed in 12 specimens caught as incidental bycatch in commercial gillnet fisheries in the Celtic Sea in 2011. Levels of organohalogen contaminants were low or undetectable (summed CB and BDE concentrations 0.04-0.85 mg kg(-1) wet weight). A notably high Cd concentration (7.2 mg kg(-1) wet weight) was observed in one mature male, whereas the range observed in the other samples was much lower (0.04-0.26 mg kg(-1) wet weight). Hg and Pb concentrations were detected only in single animals, at 0.34 and 0.08 mg kg(-1) wet weight, respectively. These contaminant levels were low in comparison to other published studies for shark species. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.