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The paper explores the dynamic relationship between sharksuckers and Atlantic Nurse sharks within a fish cleaning station in South Eleuthera, The Bahamas. Despite the prevalent symbiotic association between echeneid fishes and sharks, the specifics of their interactions, behavioral adaptations, and the influence of food availability remain understudied. The research employed a comprehensive observational approach, focusing on free-swimming and attached sharksucker' behaviors (Echeneis spp.) in the presence of Atlantic Nurse sharks. Through a month-long study, both qualitative and quantitative analyses of the behaviors were conducted. The results challenge the traditional perception of a purely mutualistic or parasitic relationship, suggesting a more complex dynamic between sharksuckers and sharks. Specifically, the study indicates an increase in boldness and competitive behaviors towards sharks in a controlled feeding setting, indicating that sharksuckers' behaviors and relationships with their hosts are constantly evolving and should not be treated as simply symbiotic. [ABSTRACT FROM AUTHOR]

Despite regulations aimed at curbing shark finning and bycatch, shark fishing mortality rates continue to escalate, partly due to unintended consequences of these policies which, along with illegal, unreported, and unregulated fishing and ghost fishing, undermine conservation efforts. The ineffectiveness of current regulations to curb shark mortality highlights the pressing need for reevaluating shark conservation strategies, especially in ecologically sensitive areas. In this context, the debate on enforcing longlining bans in multiple-use marine protected areas, including shark sanctuaries, is intensifying. Some argue for total bans to minimize incidental shark mortalities, while others highlight the socioeconomic importance of longlining, advocating for alternative conservation measures. In 2000, longline fishing was banned in the Galapagos Marine Reserve (GMR) as a precautionary measure to prevent illegal fishing of sharks and bycatch of endangered, threatened, and protected species. After 24 years of enforcement, official and anecdotal evidence indicate that illegal small-scale tuna longlining and ghost fishing are increasing threats across the reserve. This paper provides an overview of the longline fishing controversy within the GMR, incorporating scientific evidence, legal and socioeconomic considerations, and perceptions from the Galapagos small-scale fishing community. We offer novel insights and recommendations for the development of the Galapagos smallscale tuna fishery within an ecosystem approach to fisheries. This approach aims to reconcile conservation goals with the needs of local communities, while also proposing innovative solutions to address the longstanding debate surrounding longlining in the GMR. [ABSTRACT FROM AUTHOR]

Smooth-hound fillets were coated with skin gelatin extracted from the skin of the same fish. The gelatin coating solution was enriched with garden cress seed extract (GCSE) at 0.67 mg/g of gelatin. Analysis of the phenolic profile revealed that quinic acid (844 µg/g extract) was the major compound, likely to participate along with other phenolics in enhancing the preservative capacity of GCSE-gelatin coating. Interestingly, psychrophilic/mesophilic bacteria, MDA equivalent, TVB-N and FAA contents in the coated samples were significantly reduced compared to the control, proving the potential of the GCSE-enriched gelatin coating on extending fish fillet shelf-life. [ABSTRACT FROM AUTHOR]

Objective: Shark depredation, the full or partial consumption of a hooked fish by a shark before it is landed, is an increasing source of human–wildlife conflict in recreational fisheries. Reports of shark depredation in the catch‐and‐release Tarpon (also known as Atlantic Tarpon) Megalops atlanticus fishery in the Florida Keys are increasing, specifically in Bahia Honda, a recreational fishing hot spot and a putative Tarpon prespawning aggregation site. Methods: Using visual surveys of fishing in Bahia Honda, we quantified depredation rates and drivers of depredation. With acoustic telemetry, we simultaneously tracked 51 Tarpon and 14 Great Hammerheads (also known as Great Hammerhead Sharks) Sphyrna mokarran, the most common shark to depredate Tarpon, to quantify residency and spatial overlap in Bahia Honda. Result: During the visual survey, 394 Tarpon were hooked. The combined observed shark depredation and immediate postrelease predation rate was 15.3% for Tarpon that were fought longer than 5 min. Survival analysis and decision trees showed that depredation risk was highest in the first 5–12 min of the fight and on the outgoing current. During the spawning season, Great Hammerheads shifted their space use in Bahia Honda to overlap with Tarpon core use areas. Great Hammerheads restricted their space use on the outgoing current when compared to the incoming current, which could drive increased shark–angler interactions. Conclusion: Bahia Honda has clear ecological importance for both Tarpon and Great Hammerheads as a prespawning aggregation and feeding ground. The observed depredation mortality and postrelease predation mortality raise conservation concerns for the fishery. Efforts to educate anglers to improve best practices, including reducing fight times and ending a fight prematurely when sharks are present, will be essential to increase Tarpon survival and reduce shark–angler conflict. Impact statementShark depredation in recreational fisheries is an increasing source of human–wildlife conflict in the United States. This study quantified shark depredation in the Tarpon fishery and characterized the spatial ecology of Great Hammerheads and Tarpon in Bahia Honda in the Florida Keys. [ABSTRACT FROM AUTHOR]

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

Directed land-based recreational catch-and-release fishing for sandbar sharks (Carcharhinus plumbeus) is growing in popularity in Massachusetts. Working with 21 volunteer fishermen of varying experience levels, we observed and documented the fishing gear, tackle, and techniques used to catch and release 67 sandbar sharks. The postrelease fate of each shark was monitored by using an acceleration data logger (ADL) tag embedded in a custom float package that was secured to the first dorsal fin with a galvanic timed release. All 67 packages were recovered after detachment following monitoring periods of 0.15–9.98 d. Examination of the depth, tailbeat period (TBP), pitch, and roll time series from 65 ADLs that recorded data revealed high survivorship for tagged sharks, with all of them alive at the time of tag detachment. Behavioral recovery was estimated to have occurred at an average of 6.36 h after release on the basis of trends in TBP for 54 sandbar sharks with at least 10 h of postrelease acceleration data. These results indicate that sandbar sharks are remarkably resilient to catch and release in the land-based shark fishery in Massachusetts. [ABSTRACT FROM AUTHOR]

Fish oil has been known for its antioxidant, cardioprotective, anti-inflammatory, and neuroprotective characteristics due to the presence of polyunsaturated fatty acids (PUFAs) that are essential for optimal brain function and mental health. The present study investigated the effect of Carcharhinus Bleekeri (Shark Fish) oil on learning and memory functions in scopolamine-induced amnesia in rats. Locomotor and memory-enhancing activity in scopolamine-induced amnesic rats was investigated by assessing the open field and passive avoidance paradigm. Forty male Albino mice were divided into 4 equal groups (n = 10) as bellow: 1 – control (received 0.9% saline), 2 – SCOP (received scopolamine 2 mg/kg for 21 days), 3 – SCOP + SFO (received scopolamine and fish oil 5 mg/kg/ day for 21 days), 4 – SCOP + Donepezil groups (received 3 mg/kg/day for 21 days). SFO produced significant (P < 0.01) locomotor and memory-enhancing activities in open-field and passive avoidance paradigm models. Additionally, SFO restored the Acetylcholine (ACh) concentration in the hippocampus (p < 0.05) and remarkably prevented the degradation of monoamines. Histology of brain tissue showed marked cellular distortion in the scopolamine-treated group, while the SFO treatment restored distortion in the brain's hippocampus region. These results suggest that the SFO significantly ameliorates scopolamine-induced spatial memory impairment by attenuating the ACh and monoamine concentrations in the rat's hippocampus. [ABSTRACT FROM AUTHOR]

The mucus layer covering the skin of fish has several roles, including protection against pathogens and mechanical damage in which proteins play a key role. While proteins in the skin mucus layer of various common bony fish species have been explored, the proteins of shark skin mucus remain unexplored. In this pilot study, we examine the protein composition of the skin mucus in spiny dogfish sharks and chain catsharks through mass spectrometry (NanoLC-MS/MS). Overall, we identified 206 and 72 proteins in spiny dogfish (Squalus acanthias) and chain catsharks (Scyliorhinus retifer), respectively. Categorization showed that the proteins belonged to diverse biological processes and that most proteins were cellular albeit a significant minority were secreted, indicative of mucosal immune roles. The secreted proteins are reviewed in detail with emphasis on their immune potentials. Moreover, STRING protein–protein association network analysis showed that proteins of closely related shark species were more similar as compared to a more distantly related shark and a bony fish, although there were also significant overlaps. This study contributes to the growing field of molecular shark studies and provides a foundation for further research into the functional roles and potential human biomedical implications of shark skin mucus proteins. [ABSTRACT FROM AUTHOR]

Post‐release mortality threatens shark populations already imperiled by overfishing, capture stress, and a changing climate. Few studies have quantified post‐release mortality for sharks captured in land‐based recreational fisheries. From 2018 to 2021, a land‐based shark post‐release mortality study was conducted and identified water temperature and species‐specific behavior as contributing factors to post‐release mortality. The purpose of this study was to estimate the effectiveness of disseminating the recommendation for best practices to recreational shark anglers and to determine if this information influenced angler behavior. Awareness of our post‐release mortality study influenced an angler's likely release behavior, with an increase in sharks landed in the water and corresponding decrease of sharks landed on dry sand. This study demonstrated direct evidence of conservation‐based changes in angler behavior following effective research communication and involvement of anglers in research. Outreach and engagement initiatives aimed at providing best handling practices to recreational anglers should be easily digestible, widely available, and an important component of future research. [ABSTRACT FROM AUTHOR]

The management of migratory taxa relies on the knowledge of their movements. Among them, ontogenetic habitat shift, from nurseries to adult habitats, is a behavioural trait shared across marine taxa allowing resource partitioning between life stages and reducing predation risk. As this movement is consistent over time, characterizing its timing is critical to implement efficient management plans, notably in coastal areas to mitigate the impact of fisheries on juvenile stocks.In the Mexican Pacific, habitat use of the smooth hammerhead shark (Sphyrna zygaena) is poorly described, while the species is heavily harvested. Given the large uncertainties associated with the timing of out‐migration from coastal nursery grounds to offshore waters prior to reproductive maturity, a more precise assessment of smooth hammerhead shark movements is needed.Photochemical degradation of mercury imparts mass‐independent isotope fractionation (Δ199Hg) which can be used to discriminate between neonate coastal shallow habitats and the offshore deep foraging patterns of late juveniles. Here, we present the application of muscle Δ199Hg as molecular clocks to predict the timing of ontogenetic habitat shifts by smooth hammerhead sharks, based on their isotopic compositions at the initial and arrival habitats and on muscle isotopic turnover rate.We observed decreases in Δ199Hg values with shark body length, reflecting increasing reliance on offshore mesopelagic prey with age. Coastal residency estimates indicated that smooth hammerhead sharks utilize coastal resources for 2 years prior to offshore migration, suggesting a prolonged residency in these ecosystems.Policy implications. This study demonstrates how mercury stable isotopes and isotopic clocks can be implemented as a complementary tool for stock management by predicting the timing of animal migration—a key aspect in the conservation of marine taxa. In the Mexican Pacific, fishing pressure on shark species occurs in coastal habitats depleting juvenile stocks. Consequently, management decision support tools are imperative for effectively maintaining early life stage population levels over time. The finding that smooth hammerhead sharks extensively rely on highly fished habitats for 2 years after parturition supports the relevance of establishing a size limit in coastal fisheries and demonstrates how the current temporal shark fishing closure could lack efficiency for the species. [ABSTRACT FROM AUTHOR]

On September 11, 2022, two megamouth sharks (Megachasma pelagios), estimated at 3.7–4.6 m TL, were observed swimming together near the surface about 39 km off the coast of San Diego, CA, USA. Megamouth sharks are rarely observed pelagic sharks, and the film from this encounter provided new insight into the social behavior of this species. We attempt to put the behavior of these two individuals into the context of past sightings, known megamouth shark biology, and with analogous behavior observed in other shark and pelagic fish species. [ABSTRACT FROM AUTHOR]

IntroductionShore-based shark fishing in Florida is a relatively low-cost and easy-access fishery which attracts a wide variety of experienced and inexperienced anglers leading to concerns about proper handling methods of captured fish that are released either voluntarily or to comply with regulations. Proper handling methods can help reduce post-release mortality among sharks, many of which are threatened with extinction. Therefore, we considered proper handling methods as a pro-environmental behavior, which has been linked with the use of different information channels to increase conservation knowledge.MethodsWe used data from an online questionnaire to understand where anglers of this fishery obtain information about fishing skills with a particular focus on fish handling techniques and best practices for catch-and-release. Then we included their main information channels in a series of hierarchical regression models with perceived conservation knowledge and support for fishery management to explain pro-environmental behavior regarding shark conservation.ResultsWe found that most anglers learned about shore-based shark fishing through interpersonal communications with friends and family, but typically use the internet to learn more about fishing skills. While information channel use was not significantly associated with pro-environmental behavior, it was significantly associated with support for fisheries management, which in turn was associated with pro-environmental behavior among respondents.DiscussionThese findings can inform public educational outreach efforts to spread awareness of proper handling techniques and reduce instances of post-release mortality in sharks.

Anthropogenic debris is a widespread and prevalent component of aquatic systems. Organisms are increasing exposed to debris, leading to detrimental impacts through pathways such as entanglement, ingestion, and bioaccumulation. Multiple taxa interact with debris, and while the consequences to individual organisms are known in principle, their impacts at scales relevant to management are poorly understood. Despite uncertainties, decision-makers are tasked with addressing issues associated with debris and require an estimate of risks. Here, we provide a methodology to estimate the risk posed by specific debris items to a range of organisms within a management area. Risk was determined as a function of both (1) the consequence of an interaction, and (2) the likelihood of exposure, estimated through expert elicitation and empirical debris data, respectively. Using the New South Wales (NSW) Marine Estate as a case study, the methodology identified specific debris items posing risks to seven biological 'assets' (benthic assemblages, cetaceans, fish and sharks, planktonic assemblages, shorebirds, seabirds, turtles) through several pathways. Items posing 'high risk' to these biological groups included fishing-related items (fishing line, nets, traps and pots) through pathways of ingestion and entanglement. Microplastics and hard-plastic fragments also posed high risk via ingestion and bioaccumulation. The values were then assessed spatially, using marine debris databases, identifying variability in risk across the Marine Estate and thus, priority areas for management. By identifying the prominent debris items causing risks to specific and multiple assets, resources may be better allocated to maximise the efficacy of interventions. [Display omitted] • We provide a novel methodology to assess the relative risk of debris items to marine biota. • Qualitative risk values are estimated within a management area. • Entanglement and ingestion from fishing items posed elevated risk. • Bioaccumulation from plastic fragments and microplastics posed elevated risk. • Debris risk showed differences latitudinally, being higher near major population centres. [ABSTRACT FROM AUTHOR]

Recreational shark fisheries have been the subject of recent public attention because of the possible impacts on shark populations and conflicts between stakeholders.A case study is presented based on discussions that took place in summer 2018 about potential changes to policies regulating recreational land‐based shark fishing in Florida. Comments from public meetings and workshops (totalling 15.8 hours) and online comments (1,050) submitted to the Florida Fish and Wildlife Conservation Commission (FWC) were analysed using the lens of actor–network theory.The case study explores the intersection of conflicting stakeholder interests and types of knowledge, including how stakeholders variously defined the problem of user conflict in a coastal public space, and how they aligned themselves in relation to the problem and to each other. It further illustrates how shifting values and norms can intersect with changing technologies and environmental realities to produce new or increasing conflicts between natural resource user groups.This study underlines the importance and potential benefits of regulatory agencies explicitly and transparently engaging with value trade‐offs when managing conflicts among users of natural resources. [ABSTRACT FROM AUTHOR]

Fish drying is an ancient and traditional method of producing nutrientdense nourishment for humans. The present study was performed to investigate the sensory quality, microbial, biochemical, and pesticide contents of dried sharks (Scoliodon sorrakowah) from four major fish drying centers in southern Bangladesh. Sensory attributes were determined by the expert panel members; whereas, microbial quality and biochemical compositions were assessed by standard validated methods. The QuEChERS separation was used in conjunction with gas chromatography and gas chromatography-mass spectrometry to assess pesticide residues. The sensory properties showed that the dried shark fish products were of acceptable quality for human consumption in all drying center samples and did not differ significantly (P< 0.05). The aerobic plate count (APC) for dried shark fish products exceeded the regulatory limit and varied significantly (P< 0.05) across all major fish drying centers, with the exception of the shark fish product (9.6±0.09×104 cfu/g) of the Dublarchar counterparts. Likewise, the total fungal load was recorded and differed substantially (P< 0.05) in dried shark (1.78±0.03×103 cfu/g) fish products. All dried fish products were free of pathogenic bacteria such as Salmonella spp., Vibrio cholerae, Vibrio parahaemolyticus, and Listeria monocytogens. The biochemical compositions (protein, lipid, ash and moisture) and quality indices of dried shark fish products were statistically significant (P< 0.05), except for ash and pH contents (P> 0.05). In addition, the organochlorine pesticide residues (DDT and heptachlor) were not found in all dried shark fish products, and the pesticides posed no health risk at any sampling station. [ABSTRACT FROM AUTHOR]

There is an increasing need to understand the interaction of marine fauna with line fishing, both recreational and commercial, particularly in regions where shark depredation has become an increasing issue. The dynamic nature of the fishing requires underwater filming techniques that can move with the fishing activity and capture high-resolution footage enabling the identification of fauna species. In the case of shark depredation, the development of deterrent devices specifically designed for use while line fishing will require underwater footage to determine the effectiveness of those devices designed to invoke avoidance behaviours in sharks that approach hooked fish. Two new and inexpensive mounting systems were developed, enabling a range of "action" cameras to be attached to fishing lines to capture underwater footage while line fishing. Using these mounting systems with GoPro™ cameras, high-resolution video was obtained during line fishing trials in which the effectiveness of shark deterrents was investigated. The video footage enabled the identification of fish and shark species and recorded any avoidance behaviours of sharks, in response to the presence of deterrents. [ABSTRACT FROM AUTHOR]

Interspecific interactions can play an essential role in shaping wildlife populations and communities. To date, assessments of interspecific interactions, and more specifically predator–prey dynamics, in aquatic systems over broad spatial and temporal scales (i.e., hundreds of kilometers and multiple years) are rare due to constraints on our abilities to measure effectively at those scales. We applied new methods to identify space‐use overlap and potential predation risk to Atlantic tarpon (Megalops atlanticus) and permit (Trachinotus falcatus) from two known predators, great hammerhead (Sphyrna mokarran) and bull (Carcharhinus leucas) sharks, over a 3‐year period using acoustic telemetry in the coastal region of the Florida Keys (USA). By examining spatiotemporal overlap, as well as the timing and order of arrival at specific locations compared to random chance, we show that potential predation risk from great hammerhead and bull sharks to Atlantic tarpon and permit are heterogeneous across the Florida Keys. Additionally, we find that predator encounter rates with these game fishes are elevated at specific locations and times, including a prespawning aggregation site in the case of Atlantic tarpon. Further, using machine learning algorithms, we identify environmental variability in overlap between predators and their potential prey, including location, habitat, time of year, lunar cycle, depth, and water temperature. These predator–prey landscapes provide insights into fundamental ecosystem function and biological conservation, especially in the context of emerging fishery‐related depredation issues in coastal marine ecosystems. [ABSTRACT FROM AUTHOR]

A count of 6235 Chondrichthyes vertebrae was recovered from the 17th to 18th century AD NRD site (R11/859) on the Manukau Harbour, Auckland, New Zealand. These have been identified by aDNA analysis as mostly rig (Mustelus lenticulatus). To provide context for this unusual assemblage we briefly review the archaeological record of Chondrichthyes fishing in Oceania and New Zealand, and more extensively review the 19th and early 20th century ethnography of Māori shark fishing in New Zealand along with the archaeological record. Chondrichthyes were of economic, social and spiritual importance to pre‐European Māori. A variety of species were caught by a variety of techniques, including mass harvest, and could be dried for storage. Our initial reading of the ethnographic record led us to expect that the assemblage would be dominated by school shark (Galeorhinus galeus), but a closer analysis of the record showed that Māori sharking practice was diverse. The NRD assemblage encapsulates this variation. [ABSTRACT FROM AUTHOR]

Grazing by nominally herbivorous fishes is widely recognised as a critical ecosystem function on coral reefs. However, several studies have suggested that herbivory is reduced in the presence of predators, especially sharks. Nevertheless, the effects of shark presence on grazing, under natural settings, remains poorly resolved. Using ∼200 h of video footage, we quantify the extent of direct disturbance by reef sharks on grazing fishes. Contrary to expectations, grazing rate was not significantly suppressed due to sharks, with fishes resuming feeding in as little as 4 s after sharks passed. Based on our observations, we estimate that an average m2 area of reef at our study locations would be subjected to ∼5 s of acute shark disturbance during daylight hours. It appears the short-term impact of reef shark presence has a negligible effect on herbivore grazing rates, with the variable nature of grazing under natural conditions overwhelming any fear effects. • The extent of natural disturbance by reef sharks on grazing fishes was quantified. • No significant reduction in grazing occurred due to short-term 'fear effects'. • Herbivorous fishes resumed feeding in as little as 4 s after sharks passed. • ∼5 s m−2 of acute shark disturbance occurred on average during the day. • Natural variability in grazing may overwhelm any short-term 'fear effects'. [ABSTRACT FROM AUTHOR]

Shark fishing is increasingly regulated in the Caribbean region. We present new information on the characteristics, landings, species composition, and size composition of the shark fishery of Puerto Rico, a U.S. Caribbean territory, and discuss current regulatory issues. Sharks are mainly landed in a small-scale targeted fishery operating in territory jurisdiction (coast to 17 km) that supplies local demand for inexpensive fish. There are at least 16 species caught: a small number of large Tiger (Galeocerdo cuvier) and Blacktip (Carcharhinus limbatus) sharks and many small but adult Sharpnose sharks (Rhizopriodon spp.) accounted for >80% of landed weight. The catch of Sharpnose sharks was significantly skewed to males. Juvenile Scalloped Hammerhead sharks (Sphyrna lewini) were the second-most caught species but accounted for a small proportion of the landed weight and value given their small size. Differences between territory and U.S. federal regulations (17 km-370 km jurisdiction) leads to legal territory landings of federally prohibited species, especially Scalloped Hammerhead sharks, which might undermine the conservation potential of federal regulations. Scalloped Hammerhead sharks are also listed under the U.S. Endangered Species Act (ESA) making ongoing catches more problematic from a legal perspective. Scalloped Hammerhead shark catch reduction could have minimal livelihood impacts because of their low value, which presents an opportunity for stakeholders to engage on catch reduction measures. This study provides new details on how and why different shark species are caught in Puerto Rico, which could facilitate better management that protects threatened species and maintains livelihoods for people. [ABSTRACT FROM AUTHOR]

Predatory fishes on coral reefs continue to decline globally despite playing key roles in ecosystem functioning. Remote atolls and platform reefs provide potential refugia for predator populations, but quantitative information on their spatial distribution is required to establish accurate baselines for ongoing monitoring and conservation management. Current knowledge of predatory fish populations has been derived from targeted shallow diver-based surveys (<15 m). However, the spatial distribution and extent of predatory fishes on outer mesophotic shelf environments has remained under described. Middleton Reef is a remote, high-latitude, oceanic platform reef that is located within a no-take area in the Lord Howe Marine Park off eastern Australia. Here we used baited remote underwater stereo video to sample predatory fishes across lagoon and outer shelf habitats from depths 0–100 m, extending knowledge on use of mesophotic depths and habitats. Many predatory fish demonstrated clear depth and habitat associations over this depth range. Carcharhinid sharks and Carangid fishes were the most abundant predators sampled on Middleton Reef, with five predatory fishes accounting for over 90% of the predator fish biomass. Notably, Galapagos shark (Carcharhinus galapagensis) and the protected black rockcod (Epinephelus daemelii) dominated the predator fish assemblage. A higher richness of predator fish species was sampled on reef areas north and south of the lagoon. The more exposed southern aspect of the reef supported a different suite of predator fish across mesophotic habitats relative to the assemblage recorded in the north and lagoonal habitats, a pattern potentially driven by differences in hard coral cover. Biomass of predatory fishes in the more sheltered north habitats was twice that of other areas, predominantly driven by high abundances of Galapagos shark. This work adds to the growing body of literature highlighting the conservation value of isolated oceanic reefs and the need to ensure that lagoon, shallow and mesophotic habitats in these systems are adequately protected, as they support vulnerable ecologically and economically important predator fish assemblages. [ABSTRACT FROM AUTHOR]

We describe the interaction between harpoon fishing activity and sharks, which opportunistically depredated harpoon catches in the Strait of Messina. Shark bite marks were observed on harpooned swordfish during the period 2014–2020, with different damages to the catches. Most of the depredation events have focused on large swordfish, generally weighing more than 60 kg. Data on direct observations were implemented by interviews and questionnaires to fishermen aimed to recover the information on their local fishing and ecological knowledge. Fishermen provided additional data on shark-harpoon fishing interactions also supplying information on by-catch species (i.e., bluefin tuna). Therefore, these results suggest that sharks migrating through the Strait of Messina are occasionally attracted by injured prey, due to their ability to detect chemical cues, fish distress stimuli and body fluids (i.e. blood) in the water. In addition, our investigations showed an increase in shark attacks on harpooned fish over time, likely due to an increase in harpoon swordfish catches. This may be related to the effects of the driftnets' ban enforced by European Regulations in the last decades. [ABSTRACT FROM AUTHOR]

At least one third of sharks and their cartilaginous relatives (Class Chondrichthyes) meet the IUCN Red List Criteria for being threatened with extinction. Overfishing is the primary threat, with less than 4% of the world's shark catches managed for sustainability. The high‐value shark‐fin trade has gained the greatest attention as a conservation issue, yet there has been little research on shark‐fin consumer preferences, and how these might be leveraged to deliver sustainability goals. We used an online discrete choice experiment to explore preferences for price, quality, rarity, and finning among 2914 shark‐fin soup consumers in China. Overall, consumers prefer higher priced and rare shark‐fins, obtained without finning, yet we found three distinct groups with substantial heterogeneity between them. Our results provide evidence for the conspicuous consumption nature of shark‐fin use, but also suggest these preferences could be leveraged to incentivize responsible shark fishing. In addition, messaging for future unsustainable demand reduction should focus on shark‐finning and animal welfare as opposed species rarity and extinction. [ABSTRACT FROM AUTHOR]

Background: Many species of sharks, including the dusky shark Carcharhinus obscurus, are often incidentally captured in commercial pelagic and bottom longline fisheries. Incidental capture can lead to at-vessel or post-release mortality and can be detrimental to populations of threatened, endangered, or prohibited species. The estimated at-vessel mortality for dusky sharks can be high in longline fisheries and, to minimize mortality, time–area closures have been designated in the western North Atlantic Ocean to mitigate interactions with longline fisheries, yet incidental capture of dusky sharks is still common. We compared the vertical and horizontal movements of dusky sharks to the overall fishing effort and depth fished of commercial pelagic and bottom longline fisheries to determine when and where overlap is present that could lead to incidental capture. Results: Twenty-one (n = 21) dusky sharks were tagged with pop-up archival transmitting satellite tags and all were immature animals (123–200 cm FL) apart from two individuals (230 and 300 cm FL). Sharks were tagged off the coasts of North Carolina (71%) and Florida (29%). Twenty tags (95%) reported and provided tracks between 1 and 107 days (median 15 days) and 10 tags (50%) remained on sharks for > 4 days. Most individuals remained within the bottom longline closed area off the coast of North Carolina during their time at liberty. Dusky sharks primarily occupied the 20–40 m depth range 26% of the time, and overlapped with bottom and pelagic longline gears 41% and 59% of the time, respectively. Overlap was highest in the winter and spring for both commercial fisheries. Conclusions: The use of archival satellite telemetry in this study has provided valuable preliminary information on vertical and horizontal movements of immature dusky sharks in western North Atlantic Ocean. Dusky sharks may be more vulnerable to incidental capture in the pelagic longline fishery due to the high fishing effort, larger areas of horizontal overlap, and greater percentage of vertical overlap. This information will inform mitigation measures of commercial longline fisheries, which can work toward population rebuilding of the species. [ABSTRACT FROM AUTHOR]

Fishing is the major threat to marine fish populations, particularly to higher trophic‐level predators such as sharks. Many sharks, and other fish, are caught as commercial by‐catch or for recreational purposes and then released; therefore, it is important to understand the effects of capture stress on their physiology and subsequent survival. Nonetheless, although important data have been collected for some sharks, there can be substantial interspecific differences, and the consequences of capture stress are still poorly understood for most species. In this study, the authors quantified the physiological effect of capture on four catshark species endemic to Southern Africa, which are regularly discarded as by‐catch and targeted by recreational fisheries. Fifteen pyjama sharks, nine leopard sharks and nine shysharks were captured, and a blood sample was collected to measure their physiological response to capture stress. Stressed blood biochemistry was compared to samples obtained after the sharks recovered for 24 h in an underwater pen. Levels of pH and K+ were significantly lower, and lactate levels were significantly higher, in sharks immediately after capture stress compared to after the 24 h recovery period. Although the species showed a similar response to capture stress, they differed significantly in pH, K+ and lactate levels, and there was some evidence of size affecting the strength of the response to capture stress. The substantial physiological response elicited by even the relatively quick capture event in this study suggests that common fishing practices will have a stronger impact on catshark homeostasis because of longer hooking times and more disruptive fishing gear. Although the relationship between survival and physiological changes elicited by capture needs further investigation, the results provide further evidence that minimizing stress would be beneficial to maximize the survival of sharks and other fish following capture‐and‐release fishing practices. [ABSTRACT FROM AUTHOR]

Oceanic islands are productive ecosystems, and so have higher densities of many marine predators. We investigated the dynamics of elasmobranch and teleost predators in coastal waters off Réunion Island, Indian Ocean, using fisheries-independent data from a preventative shark fishing program from January 2014 to December 2019. We developed a moonlight index that calculates exact moonlight through incorporating lunar azimuth, elevation angle and island topography. We quantified spatial–temporal and environmental drivers of occurrence using zero-inflated mixed models and assessed species-specific catchability in the program. A consistent segregated pattern was observed with higher occurrence of all species at dusk and after-dusk associated with lower luminosity. Scalloped hammerhead sharks (Sphyrna lewini) and giant trevally (Caranxignobilis) were found to patrol coastal waters earlier in the day than the other species. Tiger (Galeocerdo cuvier) and bull (Carcharhinus leucas) sharks showed high spatial segregation, potentially reducing competition. Teleost predators were found more frequently inside the coral reef environment of the Marine Protected Area but there was no clear pattern for sharks. Seasonality was observed for giant trevally, stingrays, bull sharks, and giant guitarfish (Rhynchobatus australiae), with higher presence during early winter periods related to turbidity, photosynthetically available radiation, and temperature. Inter-annual variation in catch rates suggested that juvenile tiger sharks might be replacing bull sharks in nearshore habitats, and the consequences for mitigation of shark bite hazard are discussed. Operational alternatives are proposed to enhance reducing the impacts of preventative shark fishing upon critically endangered species, improve their conservation and ensure local ecosystem balance. [ABSTRACT FROM AUTHOR]

Challenges that relate to shark conservation may well be a combination of the intersection of people’s livelihoods and the ineffectiveness of management strategies. Given the current protection initiatives as well as the implementation of tighter laws restricting hunting and trade, shark conservation is still recognized as a major environmental challenge. The United Arab Emirates (U.A.E.) is used as an export hub and is one of the primary exporters of shark fins to Hong Kong, with a large proportion of fins traded to be from species at high risk of global extinction. The present-day management of shark fisheries also shows shortcomings concerning lawfulness, specifically those relating to regulatory compliance, fishing techniques, and control of finning occurrences. These concerns are not unique to the U.A.E. but emphasize the fact that there are far-reaching problems related to shark conservation. Even in a milieu of strengthened conservation measures and revised legislature, existing information on the effectiveness of a shark finning ban may still be misleading when viewed in the light of over-exploitation and global species abundance. It is therefore important that proper management must be implemented at the inception of shark fisheries. For the U.A.E., this has not always been the case. Instead, the trend was one of limited control and lack of compliance, unfortunately, resulting in a rapid decline in shark abundance, to the point where sharks struggle to recover. This paper focuses on the importance of the species, reviews the current monitoring framework, and seeks to enhance shark protection. [ABSTRACT FROM AUTHOR]

The article discusses how the uses of scientific discourses and markers, by activists and policymakers have been perceived by scientific experts and journalists and generated tensions related to science use in managing shark attack risk on Reunion Island. Following a series of shark attacks in 2011, a scientific research program was funded by French authorities to help political decision-making to reduce shark attack risk on the island's west coast, from 2011 to 2015. This program collected a large set of data to understand the ecology of the shark species implied in the attacks. The authorities have also funded a selective fishing program as an operational management device, which opposed activists from sea users' NGOs requiring shark fishing and environmental NGOs requiring sharks' protection. Based on sixteen semi-directional interviews led with local scientific experts, activists, journalists and a mandated fisherman, the study explores how activists and policymakers are perceived as having reappropriated scientific discourses to legitimize their position on shark risk management in Reunion Island. The scientific experts' perception of activists depends on the epistemology of their discipline and the values they carry about the management of living beings. Otherwise, the political shark risk management strategy on Reunion Island is perceived as preferring to use scientific rationality instead of social claims to justify public policies. These uses of science generated conflicts between scientific experts, policymakers and sea users, and argue for the need of a dialogical process between parties to manage shark attack unpredictable risk, by better considering its social interpretation. [ABSTRACT FROM AUTHOR]

A 193 cm total length female bull shark Carcharhinus leucas was captured in Florida bearing intentionally attached materials which resembled a harness. Harness‐type live bait rigs are commonly used for small baitfish; some anglers use such devices with small sharks when targeting large sharks and bony fish. Biofouling on the apparatus and the extent of the injuries indicated the material had likely been on the shark for several years. This case highlights the dangers of using these types of devices on juveniles of long‐lived species that attain a large body size. [ABSTRACT FROM AUTHOR]

Achieving fisheries compliance is challenging in contexts where enforcement capacity is limited and the incentives for rule-breaking are strong. This challenge is exemplified in Myanmar, where an active shark fishery exists despite a nationwide ban on targeted shark fishing. We used the Kipling method (5W1H) to gather a complete story of non-compliance in five small-scale fishing communities in the Myeik Archipelago. Among 144 fishers surveyed, 49% were aware of the nationwide ban. Shark fishers (24%) tended to be younger individuals who did not own a boat and perceived shark fishing to be prevalent. Compliant fishers were motivated by a fear of sharks and lack of capacity (equipment, knowledge), whereas food and income were cited as key motivations for non-compliance. The results of our study emphasize that in resource-dependent communities, improving compliance for effective shark conservation may require addressing broader issues of poverty, food security and the lack of alternatives. [ABSTRACT FROM AUTHOR]

The size and shape of red blood cells (RBCs) provide key information on life‐history strategies in vertebrates. However, little is known about how RBC shape evolved in response to environmental factors, body size and the role of evolutionary rate. Here, we analysed RBC morphometrics in a set of Teleostei (bony fishes) and Elasmobranchii (sharks and rays) species testing the hypothesis that phylogenetic relationship explains species occupation of morphospace. We collected data on cell and nucleus area and volume, nucleus:cytoplasm ratio and shape factor for 65 species belonging to 28 orders. Then, we built phylomorphospaces separately for bony fish and sharks and rays. To test whether phylogenetic relationships predicted phenotypic similarity, we calculated multivariate phylogenetic signal. We also estimated the evolutionary rate of RBC shape for each node and tip using ridge regression. Finally, we tested whether habitat and body size influenced RBC shape using a PGLS. We found a significant phylogenetic signal in RBC shape for bony fish, but not sharks and rays. Saltwater teleost species were more clustered than freshwater ones in the phylomorphospace, suggesting clade disparity. Accordingly, the rate of evolution was highly heterogeneous, with significant decrease in Acanthopterygii. Neither habitat nor body size influenced RBC shape. In conclusion, RBC shape seems to have evolved in fishes in response to multiple selective pressures independent of life‐history characters. [ABSTRACT FROM AUTHOR]

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Motivation Recent advances in high-throughput RNA-Seq technologies allow to produce massive datasets. When a study focuses only on a handful of genes, most reads are not relevant and degrade the performance of the tools used to analyze the data. Removing irrelevant reads from the input dataset leads to improved efficiency without compromising the results of the study. Results We introduce a novel computational problem, called gene assignment and we propose an efficient alignment-free approach to solve it. Given an RNA-Seq sample and a panel of genes, a gene assignment consists in extracting from the sample, the reads that most probably were sequenced from those genes. The problem becomes more complicated when the sample exhibits evidence of novel alternative splicing events. We implemented our approach in a tool called Shark and assessed its effectiveness in speeding up differential splicing analysis pipelines. This evaluation shows that Shark is able to significantly improve the performance of RNA-Seq analysis tools without having any impact on the final results. Availability and implementation The tool is distributed as a stand-alone module and the software is freely available at https://github.com/AlgoLab/shark. Supplementary information Supplementary data are available at Bioinformatics online. [ABSTRACT FROM AUTHOR]

Growth modelling is a fundamental component of fisheries assessments but is often hindered by poor quality data from biased sampling. Several methods have attempted to account for sample bias in growth analyses. However, in many cases this bias is not overcome, especially when large individuals are under-sampled. In growth models, two key parameters have a direct biological interpretation: L0, which should correspond to length-at-birth and L∞, which should approximate the average length of full-grown individuals. Here, we present an approach of fitting Bayesian growth models using Markov Chain Monte Carlo (MCMC), with informative priors on these parameters to improve the biological plausibility of growth estimates. A generalised framework is provided in an R package 'BayesGrowth', which removes the hurdle of programming an MCMC model for new users. Four case studies representing different sampling scenarios as well as three simulations with different selectivity functions were used to compare this Bayesian framework to standard frequentist growth models. The Bayesian models either outperformed or matched the results of frequentist growth models in all examples, demonstrating the broad benefits offered by this approach. This study highlights the impact that Bayesian models could provide in age and growth studies if applied more routinely rather than being limited to only complex or sophisticated applications. [ABSTRACT FROM AUTHOR]

The Greenland shark (Somniosus microcephalus) is the main bycatch species in established and exploratory inshore longline fisheries for Greenland halibut (Reinhardtius hippoglossoides) on the east coast of Baffin Island, Canada. Bycatch and entanglement in longline gear has at times been substantial and post-release survival is questionable when Greenland sharks are released with trailing fishing gear. This study investigated the effect of the type of fishing line used in the gangion and gangion breaking strength on catch rates of Greenland shark and Greenland halibut in bottom set longlines. Circle (size 14/0, 0-offset) hooks were used throughout the study. Behavior of captured sharks, mode of capture (i.e., jaw hook and/or entanglement), level of entanglement in longline gear, time required to disentangle sharks and biological information (sex, body length and health status) were recorded. Catch rates of Greenland shark were independent of monofilament nylon gangion breaking strength and monofilament gangions captured significantly fewer Greenland sharks than the traditional braided multifilament nylon gangion. Catch rates and body size of Greenland halibut did not differ significantly between gangion treatments. Although most (84%) of the Greenland sharks were hooked by the jaw, a high percentage (76%) were entangled in the mainline. The mean length of mainline entangled around the body and/or caudal peduncle and caudal fin was 28.7 m. Greenland sharks exhibited cannibalistic behavior with 15% of captured sharks cannibalized. All remaining sharks were alive and survived the disentanglement process which can be attributed to their lethargic behavior and lack of resistance when hauled to the surface. Thus, as a conservation measure fishers should be encouraged to remove trailing fishing gear prior to release. Our results are used to demonstrate benefits to the fishing industry with regard to an overall reduction in the period of time to disentangle sharks and damage to fishing gear by switching from braided multifilament to monofilament gangions in Greenland halibut longline fisheries. [ABSTRACT FROM AUTHOR]