Elasmobranch Fisheries Research Articles

DNA analysis of elasmobranch products originating from Bangladesh reveals unregulated elasmobranch fishery and trade on species of global conservation concern.

Trade involving elasmobranch products in Bangladesh is a four-decade-long practice in large scale and there is little understanding of its impact on species composition, population, and subsequent conservation. Capacity for monitoring and identification is lacking in landing and shark processing centres. A rapid survey and collection of tissue samples were performed in three landings and nine shark processing centres between 2016 and 2017 in the south-eastern coastal region of Bangladesh. Sequencing for a 707-bp fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene was used to assess the taxonomic status and species composition from 71 elasmobranch tissue samples collected from the shark processing centre only. Good quality COI sequences were obtained for 34 specimens representing 21 species—the majority of which are threatened with extinction. A total of ten species of sharks (Carcharhinus brevipinna, C. amboinensis, C. leucas, C. sorrah, C. amblyrhynchoides, Chiloscyllium burmensis, Galeocerdo cuvier, Rhincodon typus, Scoliodon laticaudus, and Sphyrna lewini), eleven species of rays (Aetomylaeus maculatus, Gymnura poecilura, Mobula mobular, M. kuhlii, Neotrygon indica, Pateobatis uarnacoides, Rhinoptera javanica, and R. jayakari), including three species of guitarfish (Glaucostegus granulatus, G. obtusus, and G. typus), were identified. Four species (14.7% of samples) were found to be listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in Appendix II. Sixteen species (59% of the specimens) were threatened with extinction according to IUCN Red List, whereas 41% were data deficient or not assessed. The results have important implications for the management of regional fisheries and the conservation of elasmobranchs as they 1) represent a preliminary understanding of elasmobranch diversity in trade; 2) depict a lack of awareness and monitoring; and 3) demonstrate a need for urgent monitoring and regulation of elasmobranch trade in Bangladesh.

A first account of the elasmobranch fishery of Balochistan, south-west Pakistan

Pakistan was listed as eighth globally in its landings of sharks and other elasmobranchs during the 1990s. Balochistan occupies over three-quarters of the coast of Pakistan yet the nature of the elasmobranch fishery there remains undocumented. Landings of elasmobranchs at landing sites were surveyed; the main species recorded were blacktip shark (Carcharhinus limbatus), bull shark (C. leucas) and spot-tail shark (C. sorrah). Altogether 25 shark species were identified, of which nine are regionally vulnerable, eight endangered, and one (the sand tiger shark, Carcharias taurus) critically endangered. Of the thirteen other elasmobranchs recorded, five are regionally vulnerable, two are endangered and one (the sawfish, Pristis pristis) critically endangered. Local fishers and processors were interviewed about their industry. Sharks were caught using both long-lines and nets, largely in May – July. The fishers retained some meat (for consumption) or liver (for the oil used for waterproofing boats), but did not process the sharks themselves, instead selling them to agents of companies that exported fins and other elasmobranch products. Results showed that recorded landings in both Balochistan and the neighbouring Sindh Province have declined to a tenth or less of peak catch. Meanwhile, the numbers of registered fishermen continued to increase, a persistent threat to elasmobranchs stocks. It is recommended that a realistic national plan of action and widespread public awareness programme, with support to fishers and processors would help to alleviate this critical situation.

Risks to biodiversity and coastal livelihoods from artisanal elasmobranch fisheries in a Least Developed Country: The Gambia (West Africa)

Developing nations in tropical regions harbour rich biological resources on which humans depend for food, income and employment, yet data to aid their management is often lacking. In West Africa, the diversity and fisheries of elasmobranchs are poorly documented, despite them being known to be economically important and vulnerable to overexploitation. Rapid qualitative surveys of fish processing and landing sites in The Gambia from 2010-2018 revealed valuable new data on species composition, biology, relative abundance, fisheries and utilisation by humans. Diversity and abundance was dominated by batoids, with a major component comprising a large guitarfish (Glaucostegus cemiculus) that was apparently targeted, and a small whipray (Fontitrygon margaritella). Nearly all taxa recorded are classified by the IUCN Red List as Critically Endangered (angel sharks Squatina spp.), Endangered, Data Deficient, or Not Evaluated; several were endemic, of exceptional evolutionary distinctness, cryptic, possibly undescribed, and rare (including stingray Hypanus rudis not apparently recorded since description in 1870). Significant threats to biodiversity, coastal livelihoods and possibly food security are identified based on the apparent importance of elasmobranch fisheries and processing; the known inability of key taxa to withstand intensive fisheries; ‘fishing down the food web’ by intensive utilisation of F. margaritella; and the absence or rarity of previously common elasmobranch species that may be severely depleted in the region. This study provides data that may act as a starting point to aid sustainability accreditation of local fin-fisheries, and demonstrates the value of inexpensive and low-resolution data collection in developing countries.

Effect of gillnet selectivity on elasmobranchs off the northwestern coast of Mexico

The regulation of mesh size is important for the effective and sustainable management of fisheries using gillnets, which are the main fishing gear used in artisanal elasmobranch fisheries throughout northwestern Mexico. Gillnet selectivity studies focusing on elasmobranchs have generally evaluated the impact on target species, and information on bycatches remains scarce. This study assessed the impact of gillnet selectivity on both target elasmobranch species and bycatches, by varying the mesh size of gillnets. Sampling was performed from 2009 to 2015 in five artisanal fishing grounds located along the northwestern coast of Mexico. The species composition and ecological parameters of the elasmobranch communities that were caught, as well as the size structure and estimated selectivity models for the main species caught, were compared between four mesh sizes: 10.16, 15.24, 20.32 and 25.4 cm (stretched opening). Overall, 32 elasmobranch species were caught, nine of which were common to all mesh sizes. Our results indicate that the species composition of the catch varied with mesh size. While the small-sized sharks Mustelus californicus and M. henlei were the main species caught by gillnets with the smaller mesh sizes, the guitarfish Pseudobatos productus and Zapteryx exasperata, and the Pacific angel shark Squatina californica were the main species caught gillnets with the largest mesh sizes. Gillnet selectivity was estimated for these latter four species as well as for the horn shark Heterodontus francisci. Optimum length for these species varied widely, increasing proportionally to mesh size. These findings emphasize the difficulty of determining an optimal minimum mesh size for multi-species fishery in this area. Finally, recommendations for future directions according to the species' vulnerability to fishing are discussed, focusing on the development of effective strategies to initiate or strengthen the recovery of elasmobranchs of the northwestern coast of Mexico.

Conservation genetics of elasmobranchs of the Mexican Pacific Coast, trends and perspectives.

One of the most critical threats to biodiversity is the high extinction rate driven by human activities. Reducing extinction rates requires the implementation of conservation programmes based on robust scientific data. Elasmobranchs are important ecological components of the ocean, and several species sustain substantial economic activities. Unfortunately, elasmobranchs are one of the most threatened and understudied animal taxa. The Mexican Pacific Coast (MPC) is a region with high elasmobranch diversity and is the seat of major elasmobranch fisheries. But it is also a developing region with several conservation and management challenges which require national and international attention. Here, we review the conservation genetics literature of elasmobranchs from the MPC. We present a synthesis of the works using samples from the region and emphasize the main gaps and biases in these data. In addition, we discuss the benefits and challenges of generating genomic information to improve the management and conservation of an elasmobranch biodiversity hotspot in a developing country. We found 47 elasmobranch genetic articles that cover <30% of the elasmobranch diversity in the region. These studies mainly used mitochondrial DNA sequences to analyse the genetic structure of commercially important and abundant species of the order Carcharhiniformes. Some of these papers also assessed mating systems, demographic parameters, and taxonomic uncertainties, all of which are important topics for efficient management decisions. In terms of conservation genetics, elasmobranchs from the MPC remain understudied. However, high-throughput sequencing technologies have increased the power and accessibility of genomic tools, even in developing countries such as Mexico. The tools described here provide information relevant for biodiversity conservation. Therefore, we strongly suggest that investment in genomic research will assist implementation of efficient management strategies. In time, this will reduce the extinction risk of the unique elasmobranch biodiversity from the MPC.

Smalltooth sawfish (Pristis pectinata Latham, 1794) in the Casamance River, Senegal: A historical perspective

Abstract A study of euryhaline elasmobranchs was conducted in the Casamance River, southern Senegal, between June 1974 and October 1975. Data were collected from 159 sawfish, comprising 158 smalltooth sawfish (Pristis pectinata Latham, 1794) and one largetooth sawfish (Pristis pristis Linnaeus, 1758). The mean total rostral tooth count for P. pectinata was 46 (range 41–53), significantly lower than the total tooth counts for the western Atlantic population. No sexual dimorphism in rostral tooth counts was apparent, in contrast to findings from the western Atlantic. The total rostral length averaged 22.9% of the total length. One hundred and forty‐four individuals were caught within the river system itself, all of them were juveniles. Fifteen adults, including the single largetooth sawfish documented during the study, were caught at the river mouth or at sea. Six sawfish, caught between May and July, bore rostral sheaths, indicating that they had recently been born. Although the Casamance and Gambia rivers are only 120 km apart, the findings from this study combined with published data collected from the Gambia River during the same period suggest the partitioning of juvenile habitats by the two sawfish species present in the region, to the level of different river systems. Both species are likely to have used the same coastal habitats as adults. The Casamance River was clearly an important habitat for smalltooth sawfish some 40 years ago, but it is unknown whether the species persists there. Intensive artisanal fisheries for sharks and rays in the region poses a significant threat to any remaining sawfishes, and a challenge for elasmobranch fisheries management.

Reproductive biology of the brown smooth-hound shark, Mustelus henlei (Chondrichthyes: Triakidae), off northwestern Mexico based on macroscopic and histological analyses

The brown smooth-hound shark Mustelus henlei is one of the most abundant species caught by the artisanal elasmobranch fishery off northwestern Mexico. The present study estimates the reproductive parameters for M. henlei using, for the first time, histological analysis and survey data collected from May 2008 to May 2016. Mustelus henlei was reported in the landings from February to November each year (n = 1,469). Total length (TL) varied between 450 and 1,530 mm (average = 753 mm, SD = 111). The sex ratio (male:female) was similar to the 1:1 ratio. Gravid females were caught during April, August, and November. Average fecundity was 9. Length at maturity was 656 mm TL for females and 636 mm TL for males, and length at maternity, estimated for the first time for this species, was 676 mm TL. The first phases of spermatogenesis and oogenesis were identified through histological analysis of gonads from immature individuals. Semen storage was detected in the oviducal gland of females at the terminal zone, whereas in males spermatozeugmata was detected in the seminal vesicles. According to the species reproductive parameters, M. henlei can be categorized as a species of high biological productivity among elasmobranchs and can thus support certain level of fishing pressure off northwestern Mexico if adequate fishing management and regulatory measures are employed. Some of the reproductive parameters that were estimated for this species in the present study were different from those estimated for other stocks from Mexican and United States waters.&#x0D; Key words: reproduction, length at maturity, length at maternity, semen storage, Mustelus henlei.

Molecular Identification of Shark Meat From Local Markets in Southern Brazil Based on DNA Barcoding: Evidence for Mislabeling and Trade of Endangered Species.

Elasmobranchs, the group of cartilaginous fishes that include sharks and rays, are especially vulnerable to overfishing due to low fecundity and late sexual maturation. A significant number of elasmobranch species are currently overexploited or threatened by fisheries activities. Additionally, several recent reports have indicated that there has been a reduction in regional elasmobranch population sizes. Brazil is an important player in elasmobranch fisheries and one of the largest importers of shark meat. However, carcasses entering the shark meat market have usually had their fins and head removed, which poses a challenge to reliable species identification based on the morphology of captured individuals. This is further complicated by the fact that the internal Brazilian market trades several different elasmobranch species under a common popular name: “cação.” The use of such imprecise nomenclature, even among governmental agencies, is problematic for both controlling the negative effects of shark consumption and informing the consumer about the origins of the product. In this study, we used DNA barcoding (mtDNA, COI gene) to identify, at the species level, “cação” samples available in local markets from Southern Brazil. We collected 63 samples traded as “cação,” which we found to correspond to 20 different species. These included two teleost species: Xiphias gladius (n = 1) and Genidens barbus (n = 6), and 18 species from seven elasmobranch orders (Carcharhiniformes, n = 42; Squaliformes, n = 3; Squatiniformes, n = 2; Rhinopristiformes, n = 4; Myliobatiformes, n = 3; Rajiformes, n = 1; and Torpediniformes, n = 1). The most common species in our sample were Prionace glauca (n = 15) and Sphyrna lewini (n = 14), while all other species were represented by four samples or less. Considering IUCN criteria, 47% of the elasmobranch species found are threatened at the global level, while 53% are threatened and 47% are critically endangered in Brazil. These results underline that labeling the meat of any shark species as “cação” is problematic for monitoring catch allocations from the fishing industry and discourages consumer engagement in conservationist practices through informed decision-making.

Examining the impact of CITES listing of sharks and rays in Southeast Asian fisheries

AbstractCITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) aims to ensure that international trade in specimens of wild animals and plants does not threaten their survival. However, measuring the effectiveness and impacts of these trade regulations for commercially exploited aquatic species remains challenging. This study highlights observed or documented changes in elasmobranch fisheries in eight Southeast Asian countries before and after the listing of sharks and rays in CITES’ Appendix II, and the influence of CITES across five pillars or sectors of a “fishery assessment framework” developed especially for this purpose. Fisheries experts reported change was most common in the “governance” (e.g., policy, regulation and compliance) and “fisher(y)” sectors (e.g., structure and effort) of the assessment framework. The smallest change was recorded in “markets” (e.g., structures and prices) and “sociocultural” sectors (e.g., consumption, livelihoods and community awareness). Overall, the study demonstrates a measurable, albeit small, mostly positive influence of CITES in five of eight countries, while noting predominantly negative influences across two, and ongoing challenges for all in maintaining legal trade of these CITES‐listed species. The study concludes by offering guidance on future needs: most notably, more effort for long‐term collection of fundamental fisher‐, stock‐ and market‐related data to inform adaptive management and facilitation of legal trade where it is shown to be sustainable. Furthermore, as many of the shark and ray species under CITES provisions are transboundary stocks, increased support for communication and cooperation among regional fishery stakeholders is an ongoing need.

The fate of the most threatened order of elasmobranchs: Shark-like batoids (Rhinopristiformes) in the Arabian Sea and adjacent waters

Shark-like batoids (Rhinopristiformes) represent of some of the most threatened families of sharks and rays. In certain regions, they are a relatively important component of elasmobranch fisheries, commonly taken as bycatch in gillnets and longlines, but also increasingly targeted for their high value fins and meat. This demand, combined with intense fishing pressure, has resulted in global population declines as well as localized extinctions of many rhinopristoids. Yet, information on the life-history, ecology, and conservation status remains scarce for most species. From 2010–2012, data was opportunistically collected from thirteen rhinopristoid species, including four endemic to the Arabian Sea and adjacent waters, landed from fisheries in the United Arab Emirates or transported from Oman. Four taxa dominated and comprised 92% of total shark-like batoid landings by number, namely Rhynchobatus spp., the Halavi guitarfish (Glaucostegus halavi), bowmouth guitarfish (Rhina ancylostoma), and Bengal guitarfish (Rhinobatos annandalei). Details of the biological characteristics, including size composition and sex ratios, are presented for each species. While there remain identification challenges related to some unresolved taxonomic issues, with several likely undescribed species occurring in the region, the first regional checklist of rhinopristoids is provided. Evidence of significant declines in landings combined with increasing fishing effort over a short time period raises concern about the status and long-term persistence of many species. Increased research to understand the biology, ecology, diversity, and resilience to harvest by fisheries is critical to the effective management of these species and an urgent precautionary approach to their conservation is warranted.

Gbm.auto: A software tool to simplify spatial modelling and Marine Protected Area planning.

Boosted Regression Trees. Excellent for data-poor spatial management but hard to useMarine resource managers and scientists often advocate spatial approaches to manage data-poor species. Existing spatial prediction and management techniques are either insufficiently robust, struggle with sparse input data, or make suboptimal use of multiple explanatory variables. Boosted Regression Trees feature excellent performance and are well suited to modelling the distribution of data-limited species, but are extremely complicated and time-consuming to learn and use, hindering access for a wide potential user base and therefore limiting uptake and usage.BRTs automated and simplified for accessible general use with rich feature setWe have built a software suite in R which integrates pre-existing functions with new tailor-made functions to automate the processing and predictive mapping of species abundance data: by automating and greatly simplifying Boosted Regression Tree spatial modelling, the gbm.auto R package suite makes this powerful statistical modelling technique more accessible to potential users in the ecological and modelling communities. The package and its documentation allow the user to generate maps of predicted abundance, visualise the representativeness of those abundance maps and to plot the relative influence of explanatory variables and their relationship to the response variables. Databases of the processed model objects and a report explaining all the steps taken within the model are also generated. The package includes a previously unavailable Decision Support Tool which combines estimated escapement biomass (the percentage of an exploited population which must be retained each year to conserve it) with the predicted abundance maps to generate maps showing the location and size of habitat that should be protected to conserve the target stocks (candidate MPAs), based on stakeholder priorities, such as the minimisation of fishing effort displacement.Gbm.auto for management in various settingsBy bridging the gap between advanced statistical methods for species distribution modelling and conservation science, management and policy, these tools can allow improved spatial abundance predictions, and therefore better management, decision-making, and conservation. Although this package was built to support spatial management of a data-limited marine elasmobranch fishery, it should be equally applicable to spatial abundance modelling, area protection, and stakeholder engagement in various scenarios.

Age and growth of the banded guitarfish Zapteryx exasperata (Chondrichthyes: Trygonorrhinidae)

The banded guitarfish (Zapteryx exasperata) is the third most abundant ray species in the artisanal elasmobranch fishery of Baja California Sur, Mexico. However, there is no biological information about its age and growth parameters, limiting the application of some quantitative population assessment methods, such as demographic models. The aim of the present study was to estimate, for the first time, age and individual growth of Z. exasperata. Biometric data from 244 individuals and 236 vertebrae were analysed. The largest number of banded guitarfish in fishery landings was observed during April and August, with a female:male sex ratio of 1:1.8. The size range was 56.4–103-cm total length (TL) for females and 51.6–92cm TL for males, with females being significantly larger than males (P&lt;0.05). The periodicity of the vertebral edge suggests that growth band pairs form annually. The estimated age structure was 5–22.6 years for females and 4–19.6 years for males, with significant differences between sexes (P&lt;0.01). The goodness-of-fit of three models was evaluated. For the von Bertalanffy growth model, the parameters were as follows. For females: theoretical maximum length, L∞ = 100.71cm TL; growth coefficient, k = 0.144year–1; and theoretical age at length zero, t0 = –0.39years. For males: L∞ = 89.78cm TL; k = 0.174year–1; and t0 = –0.65years.

Social, economic and trade characteristics of the elasmobranch fishery on Unguja Island, Zanzibar, East Africa

Understanding the socio-economic drivers underpinning fishers' decisions to target elasmobranchs is considered vital in determining sustainable management objectives for these species, yet limited empirical data is collected. This study presents an overview of elasmobranch catch, trade and socio-economic characteristics of Zanzibar's small-scale, artisanal fishery. The value of applying this information to future elasmobranch fisheries policy is demonstrated. In August 2015, interviews were conducted with fishers (n = 39) and merchants (n = 16) at two landing sites, Kizimkazi-Dimbani and Mkokotoni, along with the main market site in Stone Town. Additionally, elasmobranch catches were recorded across the same locations between June and August 2015. Elasmobranchs were listed as target species by 49% of fishers interviewed. Whilst most fishers (n = 30) stated that 76–100% of their household income came from fishing, there was variation in how elasmobranch catch and trade contributed. One-third of fishers (n = 36) that caught and sold elasmobranchs reported that 41–60% of their income came from elasmobranch catch. However, for some fishers (n = 8) elasmobranch catch represented 0–20% of their income, whilst for others (n = 4) it represented 81–100%. Differences in fisheries income and elasmobranch price could be attributed to several interacting factors including season, weather, fishing effort, fishing gear, target catch and consumer demand. Further, elasmobranch price was influenced by size and species. The study revealed information on catch, trade, markets and socio-economy that is important for future research, conservation and management of elasmobranchs and fisheries in Zanzibar. The methods utilised have potential for broader application to understudied, artisanal elasmobranch fisheries in the western Indian Ocean.

Elasmobranch fisheries in the Arabian Seas Region: Characteristics, trade and management

AbstractThe Arabian Seas Region plays an important role in the global landings and trade of sharks and rays. The United Arab Emirates (UAE) and Yemen, two countries with stark socio‐economic differences, serve as major regional trade hubs for shark and ray products and four countries (Oman, Pakistan, UAE and Yemen) supply nearly 11% of dried fin exports to Hong Kong. Yet, little information is available on the characteristics of this trade and the fisheries contributing to it. Here, we review the fisheries characteristics, trade, utilization and distribution chain of sharks and rays in 15 countries of the Arabian Seas Region based on published and grey literature, landing surveys, field observations and interviews with fishermen and traders. Although regional shark fisheries remain mostly artisanal, reported shark and ray landings represent 28% of the regional total fish production, reaching 56,074 mt in 2012 (7.3% of total world catches), with Iran, Oman, Pakistan and Yemen ranking as the primary catchers. Utilization and distribution patterns are complex, vary between landing sites and countries, and remain unmonitored. Based on widespread over‐exploitation of most teleost fisheries, current exploitation levels for most sharks and rays are potentially unsustainable. The situation is exacerbated by limited research and political will to support policy development, the incomplete nature of fisheries data, as well as insufficient regulations and enforcement. A better understanding of shark and ray fisheries will be key for regulating trade, promoting conservation and developing management initiatives to secure food security, livelihoods and biodiversity conservation in the region.

Towards sustainable fishery management for skates in South America: The genetic population structure of Zearaja chilensis and Dipturus trachyderma (Chondrichthyes, Rajiformes) in the south-east Pacific Ocean.

The longnose skates (Zearaja chilensis and Dipturus trachyderma) are the main component of the elasmobranch fisheries in the south-east Pacific Ocean. Both species are considered to be a single stock by the fishery management in Chile however, little is known about the level of demographic connectivity within the fishery. In this study, we used a genetic variation (560 bp of the control region of the mitochondrial genome and ten microsatellite loci) to explore population connectivity at five locations along the Chilean coast. Analysis of Z. chilensis populations revealed significant genetic structure among off-shore locations (San Antonio, Valdivia), two locations in the Chiloé Interior Sea (Puerto Montt and Aysén) and Punta Arenas in southern Chile. For example, mtDNA haplotype diversity was similar across off-shore locations and Punta Arenas (h = 0.46–0.50), it was significantly different to those in the Chiloé Interior Sea (h = 0.08). These results raise concerns about the long-term survival of the species within the interior sea, as population resilience will rely almost exclusively on self-recruitment. In contrast, little evidence of genetic structure was found for D. trachyderma. Our results provide evidence for three management units for Z. chilensis, and we recommend that separate management arrangements are required for each of these units. However, there is no evidence to discriminate the extant population of Dipturus trachyderma as separate management units. The lack of genetic population subdivision for D. trachyderma appears to correspond with their higher dispersal ability and more offshore habitat preference.

The elasmobranch fisheries of the Azores

In the Northeast Atlantic, elasmobranchs are a common bycatch in many fisheries, including demersal trawls, longlines, or gillnets and many countries do not have regulations or any control over the amount taken. In the Mid Atlantic, the Azores EEZ (Exclusive Economic Zone), small-scale fishing operations, artisanal and hook-and-line fishing methods are responsible for part of local total landed elasmobranch biomass, although some species are specifically focused and severely harvested by international large-scale fleets. This work provides a review and analysis of the commercial elasmobranch fisheries in the Azores EEZ, and its evolution over the last two decades, highlighting management priorities, taking into account the Northeast Atlantic elasmobranch fisheries status. In the Mid-Atlantic, elasmobranch fisheries mainly target 4 species, that are usually landed as bycatch: the tope shark (Galeorhinus galeus) and the thornback ray (Raja clavata), captured mainly by local demersal artisanal fisheries, the blue shark (Prionace glauca) and the shortfin mako shark (Isurus oxyrinchus) captured by a more industrialised fleet, including those from foreign nations. Considering elasmobranchs life history traits and fishery history, caution is advised in the development of a management strategy focusing on these species, considering the Northeast Atlantic context and regional, local and national interests.

Fish market surveys indicate unsustainable elasmobranch fisheries in the Saudi Arabian Red Sea

Elasmobranch populations worldwide are severely threatened due to overexploited and unregulated fisheries. Despite the fact that sharks and rays are captured in fisheries operating along the Red Sea coast of the Kingdom of Saudi Arabia (KSA), information on any aspects of these fisheries are very limited. Here we document the structure, composition and biological characteristics of eastern Red Sea elasmobranch fisheries based on genetic identification and market survey data over an intensive two-year sampling period at the biggest Red Sea fish market in the KSA (Jeddah). Market surveys conducted two times per month between 2011 and 2013 revealed that 24 previously confirmed elasmobranch species for the Red Sea were landed by fishers and offered for sale. Genetic identification revealed two potentially undescribed guitarfish species as well as four batoid species not formerly reported from the Red Sea. Five coastal carcharhinid species dominated the landings—Carcharhinus sorrah, C. amblyrhynchos, C. falciformis, C. limbatus, Rhizoprionodon acutus, together comprising 73% numerically of the total catch. Targeted shark fisheries reportedly exist in shark nursery areas. Most elasmobranchs outside of these areas were reportedly landed as bycatch. Most strikingly, the large majority of landed elasmobranchs were immature males or females below their reported size of sexual maturity, which suggests potential for both growth and recruitment overfishing and emphasizes the urgent need to implement region-specific management and conservation strategies to avoid the loss of these critical predators.

Composition of elasmobranch landings in Bahrain

The first detailed elasmobranch fisheries data for the Kingdom of Bahrain are presented, based on surveys of fish markets in April 2012. At least 25 species were recorded, including undescribed taxa. The milk shark Rhizoprionodon acutus was the most frequently recorded species; together with the Arabian smoothhound Mustelus mosis and banded eagle ray Aetomylaeus nichofii, these species comprised 53% of individual abundance. Sharks were almost entirely small individuals <1 m total length (TL). Males of small shark species were largely mature, whereas nearly all individuals of larger sharks were immature. For several elasmobranch species, landings were significantly biased towards males, which were largely mature. The species assemblage showed some notable differences in composition to that of adjacent Qatar, sampled at the same time of year, highlighting the importance of local data collection.

Efecto de factores ambientales y la asignación del esfuerzo pesquero sobre las capturas de la raya &lt;i&gt;Aetobatus narinari&lt;/i&gt; (Rajiformes: Myliobatidae) en el sur del Golfo de México

Aetobatus narinari represents a fisheries target in Southern Gulf of Mexico, and it is currently considered a Near Threatened species by the IUCN red list. The information available of this batoid fish includes some biological and fishery aspects; nevertheless, little is known about the factors influencing on fishing operations and catches. In order to evaluate the effect of environmental factors and the fishing effort allocation by vessels on the target fishery of A. narinari in this area, a daily basis sampling was carried out on four small-scale vessels, from January to July 2009 (the entire fishing season), in two fishing localities (Campeche and Seybaplaya). A total of 896 rays were recorded from 280 fishing trips. A General Linear Model was used to predict the factors effect on the probability that fishing operations occurred, and on the probability for captures of at least one or three or five rays per vessel-trip. The probability that fishing operations occurred off Campeche was predicted by the lunar cycle, with the highest probability in the new moon period (66%) and a probability smaller than 35% for the other periods. The probability that fishing operations occurred off Seybaplaya was predicted by wind velocity, with higher probabilities at low wind velocity than at high wind velocity, and a 50% probability of fishing operations at 12-15 km/h. Catch rates off Seybaplaya were predicted by the vessel's factor (the effect of fishing effort allocation), the North wind season and sea surface temperature. The probability for captures of at least one and three rays per vessel-trip was predicted by the vessel's factor and the North wind season. One vessel had higher catch probability (83% for at least one ray and 43% for at least three rays) than the others (69 and 70% for at least one ray and 26% for at least three rays), and during the North wind season the catch probability was higher (96% for at least one ray and 72% for at least three rays) than out of that season (68% for at least one ray and 21% for at least three rays). The probability for capture at least five rays per vessel-trip was predicted by the sea surface temperature and the North wind season. At 23 degrees C the catch probability was of 49% and the probability gradually diminished to 4% at 28 degrees C, and during the North wind season the catch probability was higher (40%) than out of that season (7%). This study shows that some environmental factors and fishermen perceptions and experience (fishing effort allocation) influence on the catch rate of A. narinari, and that these factors must be considered in future studies on elasmobranch fisheries, mainly when comparisons between catch rates among seasons or regions are analyzed.

The artisanal elasmobranch fishery of the Pacific coast of Baja California Sur, Mexico, management implications

Artisanal fisheries in Mexico account for approximately 40% of the total national catch. In 2009, Baja California Sur (BCS) had the second largest catch of elasmobranchs on the Mexican Pacific coast. This paper characterizes and describes the artisanal elasmobranch fishery of Pacific coast of BCS from 2000 to 2010. Sixty artisanal camps were documented, of which 45 targeted elasmobranchs, using primarily gillnets and longlines. We identified 52 elasmobranch species. Gillnetting accounted for 73.5% of the fishing effort and most frequently captured Rhinobatos productus, Mustelus henlei and Myliobatis californica . Longline fishing accounted for 26.5% of effort, most frequently capturing Prionace glauca and Isurus oxyrinchus . The prevalence of juveniles of several species (e.g., Cephaloscyllium ventriosum, Galeorhinus galeus, Isurus oxyrinchus , and Myliobatis californica ) within landings suggests that fishing effort may be opportunistically directed at breeding or nursery areas. Despite the dominance of species with wide distributions, we observed a significant biogeographic pattern in the abundance of some species relative to Bahia Magdalena. Results of the present study will be useful to detect changes in the structure of commercially exploited elasmobranch populations, and to provide useful indications for management purposes.