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Orcas (Orcinus orca) have a worldwide distribution and as apex predators feed on a wide variety of prey, including marine mammals, seabirds, sea turtles, cephalopods, teleost fish and elasmobranchs. Historically, there have been few observations of orca predation on large elasmobranch species nor are they commonly identified in the stomach contents of deceased orcas. In recent years there has been an increase in observational records of orca predation, such as on white sharks (Carcharodon carcharias) in South Africa, which could indicate that elasmobranchs serve a greater importance in their diet than previously considered. These events are often documented by members of the public due to the development and affordability of innovative cameras, including the use of the drones (unoccupied aerial vehicles). Here we describe new predator-prey interactions between orcas and large shark species in Cabo Pulmo National Park (CPNP), a small no-take marine protected area located in the Gulf of California. In this paper, we were able to successfully identify individuals from the described orca pods in the region; specifically, the same individuals hunting sharks over a period of nearly two years. We discuss the potential implications of these new ecological interactions, given the importance of tourism to sustain the management of CPNP, as cascading impacts have been documented elsewhere in light of orca predations on sharks. [ABSTRACT FROM AUTHOR]

Marine megafauna are critical for marine ecosystem health and their removal can cause food webs to collapse. Methods to reduce marine megafauna mortality can result in conflict between scientists, conservationists, fishers and fisheries management due to real or perceived effects on target catch, income and food security. Sensory deterrents have been used in attempts to mitigate bycatch and retain target catch quantity and quality. Here, we completed a systematic review of 116 papers, plus 25 literature reviews published between 1991 and 2022, to investigate potential for sensory deterrents to mitigate bycatch across four marine megafauna taxonomic groups (marine mammals, sea turtles, seabirds and elasmobranchs). Lights on gillnets are the only technology so far to result in significant bycatch reductions across all four taxonomic groups. It is difficult to make generalisations about the efficacy of sensory deterrents and their ability to deliver consistent bycatch reductions. The efficacy of each method is context dependent, varying with species, fishery and environmental characteristics. Further research is recommended for field studies assessing bycatch mitigation in all sensory deterrents, including combinations of deterrents, to assess effects on target and non-target species. The associated issues of habituation, habitat exclusion and foraging around fishing gear are important, although reducing mortality of vulnerable species should remain the highest priority for conservation and preserving ecosystems that fishers depend on. Multiple complementary measures will be required to achieve consistent bycatch reduction targets in many fisheries, of which sensory deterrents could play some part if implemented appropriately. [ABSTRACT FROM AUTHOR]

The present paper represents the first description of abnormal hermaphroditism in Galeus melastomus (Rafinesque, 1810). The black mouth cat shark specimen, collected in summer from southern Tyrrhenian Sea at the entrance of Salerno gulf, showed a basic intersexuality characterized by the presence of male secondary and female primary sexual characters. The reproductive system has been described with an accurate morphological analysis, also including a histological assessment of oocytes. Results showed the presence of only right clasper, not exceeding the pelvic fin in length, with the absence of internal males' sexual organs. Concerning the female primary characters, the analysis of histological assessment showed the structure of mature oocyte, confirming the maturity stage of a mature female in active extruding stage, as highlighted by the macroscopic morphological analysis. Despite in many marine organisms' hermaphroditism is a physiological condition showed by specimens during their lifecycle, in Elasmobranchs this is considered an abnormal condition, with some exceptions. The lack of information on hermaphroditism in elasmobranchs form the Mediterranean Sea requires an increase of scientific community's attention, improving the knowledge on the reproductive biology of this sensitive taxon. This is essential to enhance the conservation of elasmobranchs populations in the entire Mediterranean basin. [ABSTRACT FROM AUTHOR]

This paper attempts a synthesis of the evolution of large pelagic filter-feeding animals from the Cambrian to the present. Lineages known or suspected to have evolved large pelagic filter-feeding species are, in the order of their appearance, stem euarthropods, agnathan fishes, nautiloid cephalopods, placoderms, sharks, bony fishes, reptiles, ammonite cephalopods, and mammals. I discuss evolutionary trends which are apparent from the evolution of the large pelagic filter-feeding niche, which are 1. a size increase relative to their ancestral species, 2. the transition between taxonomic groups giving rise to pelagic filter-feeders, with vertebrates dominating the post-Cambrian, 3. the evolution of large pelagic filter-feeders from large carnivores in most, but not all cases, and 4. lengthy gaps in the record of pelagic filter-feeders around four of the big five mass extinctions. [ABSTRACT FROM AUTHOR]

The Baraka's whipray (Maculabatis ambigua) is a major constituent of small‐scale fisheries catch in the south‐western Indian Ocean. Despite this, little is known of its life‐history or exploitation status. We provide the first estimates of crucial life‐history parameters and the maximum intrinsic population growth rate rmax, using specimens collected from small‐scale fisheries landings in Kenya, Zanzibar and Madagascar (with northern Madagascar representing a range extension for this species). We assess the relative risk of overexploitation by combining rmax with estimates of total Z, fishing F, and natural M mortality, and an estimate of the exploitation ratio E. The data indicate that Baraka's whipray is a medium‐sized, fast‐growing, early maturing species, with a relatively long lifespan. This results in a high rmax relative to many other elasmobranchs, which when combined with estimates of F suggests that the species is not at imminent risk of extinction. Yet, estimates of exploitation ratio E indicate likely overfishing for the species, with full recruitment to the fishery being post‐maturation and exploitation occurring across a broad range of age and size classes. Thus, Baraka's whipray is unlikely to be biologically sustainable in the face of current fisheries pressures. This paper makes an important contribution to filling the gap in available data and is a step towards developing evidence‐based fisheries management for this species. Further, it demonstrates a simple and widely applicable framework for assessment of data‐poor elasmobranch exploitation status and extinction risk. [ABSTRACT FROM AUTHOR]

Rapid global expansion of offshore wind farms, tidal, and wave technologies signifies a new era of renewable energy development. While a promising means to combat the impacts of climate change, such developments necessitate fine-scale monitoring of biological communities to determine impacts associated with construction, operation, and eventual decommission. Here, we evaluate the performance of a gridded, Innovasea Systems, Inc. fine-scale acoustic telemetry positioning system (FSPS, n = 20 acoustic receivers) for tracking behaviors of diverse, temperate fish assemblages in relation to a subsea cable route supporting the Ørsted offshore wind development in coastal New York. We examined array performance through positioning error derived from receiver reference transmitters and tracked animals (n = 260) comprising 17 species of teleost and elasmobranch. We evaluated the effects of environmental variables (temperature, tilt, noise, and depth), transmitter power, individual movement rates, and receiver loss on horizontal positioning error (HPE) and route mean squared error (RMSE). Across a 16-month deployment period, many positions were derived for Atlantic sturgeon (n = 2,612), black sea bass (n = 9,175), clearnose skate (n = 10,306), summer flounder (n = 13,304), and little skate (n = 15,186), suggesting that these species may serve as sentinel candidates for assessing behavioral changes following construction, operation, and decommission. We found that receivers placed at the boundary of the grid exhibited higher HPE and RMSE, however these errors did not significantly change despite large receiver losses (25%). Generalized Linear Models revealed that temperature, noise, tilt, and depth were often significant predictors of HPE and RMSE, however, a substantial amount of variance was not explained by the models (~ 70%). Average movement rates ranged from 1.1 m s−1 (common thresher shark) to 0.03 m s−1 (little skate and summer flounder) but had minimal effects on positioning error. Finally, we observed that higher transmitter powers (158 dB) may lead to higher and more variable HPE values. Overall, these findings provide new insight into the drivers of FSPS array performance and illustrate their broad utility for monitoring fish behavior associated with offshore marine developments. [ABSTRACT FROM AUTHOR]

In developing regions, coastal communities are particularly dependent on small-scale fisheries for food security and income. However, information on the scale and impacts of small-scale fisheries on coastal marine ecosystems are frequently lacking. Large marine vertebrates (marine mammals, sea turtles and chondrichthyans) are often among the first species to experience declines due to fisheries. This paper reviews the interactions between small-scale fisheries and vulnerable marine megafauna in the southwestern Indian Ocean. We highlight an urgent need for proper documentation, monitoring and assessment at the regional level of small-scale fisheries and the megafauna affected by them to inform evidence-based fisheries management. Catch and landings data are generally of poor quality and resolution with compositional data, where available, mostly anecdotal or heavily biased towards easily identifiable species. There is also limited understanding of fisheries effort, most of which relies on metrics unsuitable for proper assessment. Management strategies (where they exist) are often created without strong evidence bases or understanding of the reliance of fishers on resources. Consequently, it is not possible to effectively assess the current status and ensure the sustainability of these species groups; with indications of overexploitation in several areas. To address these issues, a regionally collaborative approach between government and non-governmental organisations, independent researchers and institutions, and small-scale fisheries stakeholders is required. In combination with good governance practices, appropriate and effective, evidence-based management can be formulated to sustain these resources, the marine ecosystems they are intrinsically linked to and the livelihoods of coastal communities that are tied to them. [ABSTRACT FROM AUTHOR]

Global marine biodiversity declines require bold and ambitious plans to safeguard ecosystem services. Overfishing, habitat loss and projected climate impacts have yielded deleterious effects on marine predators, in particular, driving increasing threat of extinction for many shark species with implications for ecosystem health. Identifying and protecting critical habitat areas for sharks is fundamental to their protection, and may allow for species recovery. Here we use baited remote underwater video stations to investigate spatial and temporal patterns of habitat use by sharks in a Special Area of Conservation (SAC) that is centrally important to the regional blue economy in the UK, the Cardigan Bay SAC. Our results show heterogeneous spatial habitat use and temporal trends in habitat sharing between smallspotted catsharks Scyliorhinus canicula and nursehounds S. stellaris. Nearshore reef habitats are substantially more important than non-reef habitats for both species. The relative abundance of each species, however, is roughly inversely seasonally proportional, with S. canicula and S. stellaris relative abundance highest in March and September, respectively. Temporal niche partitioning may be an important mechanism in marine systems, but has not been widely investigated in sympatric shark communities. These findings are directly relevant for ongoing development of the Welsh Marine Evidence Strategy (2019-2025) and the Welsh National Marine Plan, particularly to inform spatial planning to strengthen the role of SAC management design in protecting important shark areas. [ABSTRACT FROM AUTHOR]

Context: The blackspot shark (Carcharhinus sealei) is a small-bodied coastal shark often incidentally caught in fisheries across South-east Asia. Aims: This study aimed to document the species' biology, ecology, fisheries and markets to inform conservation. Methods: In total, 103 blackspot sharks from Indonesia (n = 101) and Singapore (n = 2) were examined to determine biological parameters (growth rate, age at maturity, reproductive traits and diet). An interview with a Singaporean seafood supplier gave insight to population trends, fisheries and markets. Key results: Males attained a maximum age of 9 years, the smallest mature individual measured 709-mm stretched total length (STL), with 50% reaching maturity at 6.15 years. Females attained a maximum age of 11 years, the smallest mature individual measured 730 mm STL, with 50% reaching maturity at 6.12 years. The species has an overall growth rate (k) of 0.37 year−1. Reproduction was asynchronous, with only two pups produced per litter. Crustaceans dominated the diet of juveniles, whereas bony fishes and cephalopods dominated the diets of adult males and adult females respectively. Conclusions: Blackspot sharks have a moderately fast growth rate, but a late age-at-maturity and a low fecundity. Diet differed between the sexes as well as adults and juveniles. Implications: The low fecundity and late maturity of blackspot sharks increase their vulnerability to exploitation. Blackspot sharks are now listed on CITES-Appendix II, but mortality may remain high because they are reportedly often caught incidentally. Blackspot sharks from Riau Islands, Indonesia, have a late maturity (~6 years old) and low fecundity (litters of two pups). Mature males primarily eat bony fishes, mature females primarily eat cephalopods, whereas juveniles primarily eat crustaceans. A seafood supplier who was interviewed has perceived population declines and stated that the species is mostly caught incidentally. [ABSTRACT FROM AUTHOR]

Cownose rays (Rhinoptera bonasus) are schooling rays commonly displayed in large groups in public aquariums. They are long-lived, have an annual reproductive cycle, and readily breed in managed care with most pregnancies culminating with the unaided and successful birth of a single neonate. Occasionally, females are observed to have prolonged pregnancies or suffer dystocia during parturition and intervention via a cesarian section (C-section) is required to deliver the neonate. Monthly reproductive monitoring at Ripley's Aquarium of the Smokies using ultrasound to stage pregnancies allows for the prediction of anticipated due dates and guides the decision to assist with delivery. Recognizing when to assist birth and best practices for performing C-section are important for the reproductive health, sustainability, and longevity of this species in managed care. This report describes a surgical technique for C-section in cownose rays and includes short-term complications and longterm outcomes for females. [ABSTRACT FROM AUTHOR]

Long non-coding RNAs (lncRNAs) are involved in numerous biological processes and serve crucial regulatory functions in both animals and plants. Nevertheless, there is limited understanding of lncRNAs and their patterns of expression and roles in sharks. In the current study, we systematically identified and characterized lncRNAs in the blue shark (Prionace glauca) from four tissues (liver, spleen, muscle, and kidney) using high-throughput sequencing and bioinformatics tools. A total of 21,932 high-confidence lncRNAs were identified, with 8984 and 3067 stably and tissue-specific expressed lncRNAs, respectively. In addition, a total of 45,007 differentially expressed (DE) lncRNAs were obtained among tissues, with kidney versus muscle having the largest numbers across tissues. DE lncRNAs trans target protein-coding genes were predicted, and functional gene ontology enrichment of these genes showed GO terms such as muscle system processes, cellular/metabolic processes, and stress and immune responses, all of which correspond with the specific biological functions of each tissue analyzed. These results advance our knowledge of lncRNAs in sharks and present novel data on tissue-specific lncRNAs, providing key information to support future functional shark investigations. [ABSTRACT FROM AUTHOR]

Context: The quagga catshark (Halaelurus quagga) is a small-sized (~370-mm total length), deep-water catshark (Family: Pentanchidae), assessed as Data Deficient on the IUCN Red List. Aim: We aimed to bridge critical knowledge gaps on aspects of the life history and exploitation of H. quagga to make a meaningful Red List assessment, and develop management plans. Methods: Specimens landed as bycatch in three harbours along the Laccadive Sea coast of south-western India were examined to gather the first information on exploited length classes and aspects of reproductive biology. Key results: Halaelurus quagga had a female-dominated sex ratio, a positively allometric growth in females, and isometric growth in males. Mature H. quagga males ranged between 294 and 336 mm, and females between 315 and 370 mm, with pregnant females carrying two, three or four egg cases with embryos in each uterus. Conclusions: This study provides the first information on the biology and exploitation of H. quagga , showing that the species is landed (and discarded) as bycatch in trawl fisheries, with the catches comprising a significant amount of reproductively active individuals. Implications: The intense deep-sea bottom-trawling off south-western India is a major threat to H. quagga , and, if left unmanaged, could likely trigger a threatened category on the IUCN Red List. The first study on the exploitation levels and aspects of biology of Halaelurus quagga , a poorly known deep-water catshark, showed a female-dominated sex ratio, a positively allometric growth in females and isometric growth in males. Mature H. quagga males ranged between 294 and 336 mm, and females between 315 and 370 mm, with pregnant females carrying two, three or four egg cases, with embryos in each uterus. This species is landed (and discarded) as bycatch in shrimp fisheries, with the catches comprising a significant amount of reproductively active individuals. [ABSTRACT FROM AUTHOR]

Context: For threatened marine species, data on their vertical habitat use patterns can reveal risk of interactions with fishing gear and can inform bycatch avoidance strategies. Such data are lacking for young porbeagles (Lamna nasus), which are captured as bycatch in north-western Atlantic fisheries. Aims: We aimed to examine temporal patterns in diving and characterise vertical habitat use of young porbeagles during summer and autumn. Methods: We used data from short-term (28-day), high-resolution (5-min interval) pop-off satellite tags attached to 14 young (young-of-the-year and 1-year-old) porbeagles to model depth use. Key results: Occupied depths ranged from the sea surface to 679 m, with ambient water temperatures of −0.2 to 26°C. Diel period and season were factors related to depth use. Conclusions: Sharks exhibited a diel activity pattern characterised by more extensive use of the water column during the day while remaining primarily at the surface at night. Depth use differed between seasons, with summer characterised by greater affinity for surface waters (0–10 m) compared to autumn. Implications: Young porbeagles are at risk of interaction with active fisheries on the continental shelf, but interactions may be reduced by setting gear deeper at night or during summer. The depth use of young porbeagles was investigated for the first time during the summer and autumn in the north-western Atlantic. Depth use varied on both daily and seasonal scales, with sharks occupying surface waters during the night and summer, and diving deeper during the day and autumn. Results can inform bycatch reduction strategies for this vulnerable life stage. [ABSTRACT FROM AUTHOR]

Elasmobranchs are common, iconic species in public aquaria; their wild counterparts are key members of marine ecosystems. Post-mortem examination is a critical tool for disease monitoring of wild elasmobranchs and for management of those under human care. Careful necropsy of the head, with a focus on clinically relevant anatomy, can ensure that proper samples are collected, increasing the chance of presumptive diagnoses prior to slower diagnostic workup. Immediate feedback from a thorough head necropsy allows for faster management decisions, often identifying pathogens, routes of pathogen entry, and pathogenesis, which are current shortcomings in published literature. This article proposes a protocol for necropsy of the elasmobranch chondrocranium, emphasizing unique anatomy and careful dissection, evaluation, and sampling of the endolymphatic pores and ducts, inner ears, brain, and olfactory system as part of a complete, whole-body necropsy. Extensive use of cytology and microbiology, along with thorough sample collection for histology and molecular biology, has proven effective in identifying a wide range of pathogens and assisting with characterization of pathogenesis. The cause of mortality is often identified from a head necropsy alone, but does not replace a thorough whole-body dissection. This protocol for necropsy and ancillary diagnostic sample collection and evaluation was developed and implemented in the necropsy of 189 wild and aquarium-housed elasmobranchs across 18 species over 13 years (2011--2023) in California. Using this chondrocranial approach, meningoencephalitis was determined to be the primary cause of mortality in 70% (118/168) of stranded wild and aquarium-housed elasmobranchs. Etiology was largely bacterial or protozoal. Carnobacterium maltaromaticum bacterial meningoencephalitis occurred in salmon sharks (Lamna ditropis), shortfin mako sharks (Isurus oxyrinchus), common thresher sharks (Alopias vulpinus), and one Pacific electric ray (Tetronarce californica). Miamiensis avidus was the most common cause of protozoal meningoencephalitis and found almost exclusively in leopard sharks (Triakis semifasciata) and bat rays (Myliobatis californica) that stranded in San Francisco Bay. Bacterial pathogens were found to use an endolymphatic route of entry, while protozoa entered via the nares and olfactory lamellae. Trauma was the second most common cause of mortality and responsible for 14% (24/168) of wild shark strandings and deaths of aquarium-housed animals. [ABSTRACT FROM AUTHOR]

This opinion piece presents empirical evidence to examine possible negative consequences of the use of penetrative tagging as used on the great white shark (GWS). Tagging programs currently using this method attach SPOT (Spatial Positioning Only Tags) using corrodible bolts inserted through the dorsal fin while the shark is taken out of water. Such methods can cause harm to the tagged individual. Possible adverse effects include impacts on growth, tag biofouling, wounds, heightened stress, and hemorrhaging. This method may adversely impact dorsal fin structure and the shark's hydrodynamics. As a result, data collected may not be reflective of natural behavior. Bolted SPOT are semi-permanently affixed to the shark but can have a battery life of approximately 3.5 years. Most of these tags (69%) ceased transmitting in less than 2 years. Alternative tagging technologies exist as more humane options. [ABSTRACT FROM AUTHOR]

The incidental capture of non-target species (bycatch) in tuna fisheries impacts some marine vertebrates, particularly species with vulnerable life histories such as manta and devil rays (mobulids). There is broad interest in reducing mobulid bycatch in tuna purse seine fisheries, with existing efforts mainly focusing on reducing post-capture mortality rates. We explore a novel potential pre-capture mobulid bycatch avoidance strategy for the tuna purse seine fishery using communication between fishing vessels and associated spotter helicopters. We conducted a survey of tuna purse seine helicopter pilots, spotters, and fishers operating in the eastern Pacific Ocean (n = 33) to ascertain the ability of helicopter crew to detect mobulids prior to capture and communicate bycatch avoidance with vessel crew. Results indicate over half of the helicopter crew report being “always” or “sometimes” able to sight and identify mobulids and that helicopter crew regularly communicate mobulid sightings to the vessel already. Given that an average of 63% of class-6 vessel trips between 2017 to 2022 carried onboard helicopters, our results suggest that helicopter-vessel communication could be feasible and scalable for mobulid bycatch detection, enabling potential bycatch avoidance and early alerts for proper handling protocols. We also identify the potential use of helicopter detection to improve research efforts for mobulid conservation (e.g., data collection of population and habitat observations). This study is the first to investigate the utility of helicopter-vessel communication as a bycatch mitigation strategy for elasmobranchs and identifies research and management directions that could be further investigated to avoid bycatch of mobulids. [ABSTRACT FROM AUTHOR]

Orcas (Orcinus orca) have a worldwide distribution and as apex predators feed on a wide variety of prey, including marine mammals, seabirds, sea turtles, cephalopods, teleost fish and elasmobranchs. Historically, there have been few observations of orca predation on large elasmobranch species nor are they commonly identified in the stomach contents of deceased orcas. In recent years there has been an increase in observational records of orca predation, such as on white sharks (Carcharodon carcharias) in South Africa, which could indicate that elasmobranchs serve a greater importance in their diet than previously considered. These events are often documented by members of the public due to the development and affordability of innovative cameras, including the use of the drones (unoccupied aerial vehicles). Here we describe new predator-prey interactions between orcas and large shark species in Cabo Pulmo National Park (CPNP), a small no-take marine protected area located in the Gulf of California. In this paper, we were able to successfully identify individuals from the described orca pods in the region; specifically, the same individuals hunting sharks over a period of nearly two years. We discuss the potential implications of these new ecological interactions, given the importance of tourism to sustain the management of CPNP, as cascading impacts have been documented elsewhere in light of orca predations on sharks.

A new ascaridoid nematode Mawsonascaris zhoui sp. nov. collected from the granulated guitarfish Glaucostegus granulatus (Cuvier) (Rajiformes: Rhinobatidae) in the Taiwan Strait (off Xiamen, Fujian Province, China) is described and illustrated in this paper. The new species can easily be distinguished from its congeners by the absence of an intestinal caecum, the presence of a single, median precloacal volcaniform papilla, a pair of paracloacal double papillae and 10–11 precloacal papillae in the male. In addition, the paratypes of Raphidascaroides myliobatum Yin & Zhang, 1983 collected from the Japanese eagle ray Myliobatis tobijei Bleeker (Rajiformes: Myliobatidae) in the Taiwan Strait (off Chongwu, Fujian Province, China) were also re-examined and the morphology of the species reveals that it also belongs to the genus Mawsonascaris, as M. myliobatum (Yin & Zhang, 1983) comb. nov. An identification key to the species of Mawsonascaris is provided. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to examine the basic life history of a lightly exploited stock of Squalus suckleyi in the Gulf of Alaska to establish a baseline for future comparison and to provide critical information for stock assessments. Average total length (total length extended) of females (87·7 cm) was significantly larger ( t-test, t = −12·57, d.f. = 1533, P < 0·01) than males (80·3 cm); size at 50% maturity (74·5 and 97·3 cm, males and females, respectively) and age at 50% maturity (21 and 36 years, respectively) were also significantly different between the sexes ( i.e. bootstrapped 95% c.i. did not overlap). Total average fecundity was 8·5 pups per female, and individual fecundity was a linear function of either length or whole mass. The best estimate of instantaneous natural mortality was 0·097. The delayed age of maturity, low natural mortality and low rates of reproduction imply that only very low rates of fishing mortality are sustainable. Finally, this paper provides the first reported evidence that a small percentage of the adult females may undergo an extended resting period between pregnancies of ≥1 years. [ABSTRACT FROM AUTHOR]

In this paper, the population biology of the velvet belly lanternshark Etmopterus spinax was studied and life-history coefficients determined. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year-old females were found. Several growth models were fitted and compared for both size-at-age and mass-at-age data, showing that even though this is a small-sized species, it has a relatively slow growth rate. This species matures late, specifically at 49·6 and 42·5% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 9·94 oocytes and a mean uterine fecundity of 7·59 embryos per reproductive cycle. This species seems to have a long reproductive cycle, and even though no conclusive data were obtained, a 2–3 year cycle is possible. The estimated coefficients indicate that this species has a vulnerable life cycle, typical of deepwater squalid sharks. Given the high fishing pressures that it is suffering in the north-east Atlantic, this fish may already be facing severe declines or in risk of facing them in the near future. [ABSTRACT FROM AUTHOR]

The Chagos Archipelago's vast no‐take marine protected area (MPA, 640,000 km2) provides refuge for elasmobranchs facing unsustainable depletion by fisheries. Nonetheless, illegal, unreported and unregulated (IUU) fishing poses a substantial threat, and potential future changes to the use of the MPA could render elasmobranchs increasingly vulnerable to exploitation, putting geographically isolated populations, such as reef manta rays (Mobula alfredi) at risk of local extinction. Therefore, the species' long‐term movements and habitat use must be identified to help prioritize current enforcement activity and inform future spatial planning.Passive acoustic telemetry and modelled environmental data were used to investigate variations in 42 tagged M. alfredi utilization of a meso‐scale aggregation hotspot, Egmont Atoll, between 2019 and 2022.Mobula alfredi displayed the highest levels of residency ever reported (77%), with prolonged absences (>2 months) limited to seven individuals. Egmont atoll was used year‐round, with activity peaks during the southeast monsoon (April – November), particularly at sites on the southwest, while sites on the northwest were predominately frequented in the northwest monsoon (December–March). Tags were most likely to be detected when the Indian Ocean Dipole (IOD) was in a positive phase with a greater mixed layer depth, associated with a depression of chlorophyll α levels in the Indian Ocean. Thus, M. alfredi may be particularly reliant on Egmont Atoll, where they are predominantly observed feeding, when prey resources are limited elsewhere.In a region where the threat of fisheries is of increasing concern, the identification of crucial M. alfredi habitats is essential for conservation management planning. Given the significant role of Egmont Atoll for the local population, regular IUU enforcement patrols are crucial, particularly during the southeast monsoon. Any future changes to the MPA should prioritize preserving and actively enforcing no‐take regulations at Egmont Atoll. [ABSTRACT FROM AUTHOR]

Detecting changes in the distribution and abundance of marine species that are cryptic or occurring in very low abundances is difficult, but essential for assessing their status and informing management. One way of quantifying these changes is through the collation of opportunistic records. We reconstruct the population trajectory and distribution of the common stingray Dasyatis pastinaca around Great Britain, using opportunistic records, mostly obtained by recreational anglers. We tested if D. pastinaca declined in abundance and body size in response to fishing and if their distribution has shifted northwards in response to warming seas. We obtained 518 records covering the period 1838–2020. After correcting for observation effort, D. pastinaca catches reported by anglers showed no long-term trend over 50 years, but decreased from 1970 to 1995 and an increase in abundance since 1995. While records of species occurrence were found around much of Great Britain, nearly all were from south of 54° latitude, and records have contracted southwards since 2000. No trend in maximum size through time was detected. In conclusion, we did not find support for the hypothesized declines in abundance and body size or a northward shift in distribution of D. pastinaca and instead found a southward contraction. [ABSTRACT FROM AUTHOR]

Catch-and-release angling is a popular recreational pastime and an essential component of many fish research programmes. Marked physiological disturbances have been documented in elasmobranchs in response to angling and handling, but skates and rays remain understudied. Here, we describe for the first time the physiological responses of the critically endangered flapper skate (Dipturus intermedius) to angling, handling and tagging in Scotland. Sixty-one skate were captured by angling as part of a tagging research programme. We assessed individual health, measured blood parameters at two time points (post-capture and prior to release) and recorded heart and respiratory rates during handling and the surgical insertion of acoustic tags. Injuries or infections were identified in 10% of individuals and attributed to prior angling in two cases. Skate generally experienced a mild metabolic acidosis characterized by decreases in blood pH and bicarbonate and increases in lactate and glucose. Respiratory acidosis characterized by limited increases in PCO2 was also observed. The degree of acidosis was greater with warmer sea temperatures and longer fight times, and worsened during the time that skate were handled on deck. Heart rates during handling were negatively associated with body size, positively associated with temperature and also linked to time on the line. Taken together, our results suggest that elevated fight times and temperatures increase the physiological stress experienced by rod and reel-caught flapper skate. Efforts to reduce fight times and minimize heat exposure (including shading, irrigation and reduced handling time) should be beneficial for skate. [ABSTRACT FROM AUTHOR]

The ACCOBAMS Survey Initiative (ASI) is the first synoptic large-scale survey of the entire ACCOBAMS Area and as such it plays a key role in filling the current gaps in our biological and ecological knowledge of large vertebrate species occurring in the region. Data gathered during the ASI were analyzed in a distance sampling surface-modelling framework to assess the summer distribution, densities and patterns, as well as to investigate the correlates of these parameters, for large vertebrate species and taxa in the Mediterranean Basin. Static and dynamic explanatory variables, including water depth (m), distance to depth contours (km), distance to canyons and seabed slope (km), sea surface temperature (°C), mixed layer depth (m) and levels of chlorophyll-a (mg/l), were considered to predict density and compute its variance spatially at a resolution of 10x10 km. A strong longitudinal gradient from low densities in the east to high densities in the west is shared by most taxa. In addition, several taxa also showed a less marked latitudinal gradient varying in direction according to species, and finally, a few of them exhibited patchy distributions. [ABSTRACT FROM AUTHOR]