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Brazil currently ranks as the 11th producer and 1st importer of shark meat around the world. Data available from the FAO software FishStatJ along with data from regional sources, such as governmental bulletins, scientific papers, gray literature and internet were revisited to identify the main issues surrounding pelagic shark fisheries, trade and consumption in the largest country in South America. Among the main findings, it was noted that Brazil has not properly collected fishery statistics since 2007, that many species of threatened sharks are freely landed and traded even though it is prohibited by local legislation and/or international recommendations (regional fisheries management organizations). The blue shark ( Prionace glauca ) is the most frequently recorded shark in the official bulletins and is currently a locally targeted species. Additionally, the significant imports of this species from 23 other countries that also provide fins for Asia has drawn attention in recent decades. Regarding consumption, shark is considered to be low-value seafood compared to more common fish, such as groupers and snappers, and most Brazilians actually do not know that they are eating sharks. At present, the proportion of threatened elasmobranchs (in which sharks are included) in Brazil (33%, of 145 species) exceeds the global rate identified for the group (25%), and, until the present moment, no measure related to the management of species has been implemented. As advice, Brazil urgently needs to restructure its fishery information collection systems, management strategies and to tighten sanitary and labeling regulations for the marketing of fish. [ABSTRACT FROM AUTHOR]

Predatory fishes often have strong top-down effects on coastal marine ecosystems and are considered a priority for conservation and management. Predator activity can influence prey distribution, abundance, and foraging behaviors, and is likely to influence habitat by impacting ecological and environmental characteristics as well as presence of competitor species. There are knowledge gaps of the effects of functional diversity, non-consumptive predator association, and environmental effects on fish assemblages, particularly within the Greater Caribbean region. In this study, effects of apex marine predatory fishes on diversity and abundance of prey ichthyofaunal communities were examined in putative predation low-risk (north side = lagoon) and high-risk (south side = flat) areas around South Bimini Island, The Bahamas. Baited remote underwater video surveys (BRUVs, n = 100 sites) deployed in the two nearshore habitat types captured abundance and potential predator-prey interactions, which were compared to assess potential risk effects within low-risk and high-risk habitats. Results showed a difference in ichthyofaunal communities between the two habitats, with teleost abundance highest on the south side. Depth, temperature, salinity, and dissolved oxygen were significantly linked to biotic assemblages. There were no differences in flight (escape) behavior of prey from predator (sharks versus great barracuda), suggesting that predator avoidance was a minimal factor in ichthyofaunal community structures. In the rapidly developing Greater Caribbean region, knowledge of ichthyofaunal communities and predator-prey interactions in different coastal habitats can better inform management regarding ecological changes over time and between island locations. [ABSTRACT FROM AUTHOR]

Copyright of Neotropical Ichthyology is the property of Neotropical Ichthyology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sharks and rays are among the most threatened vertebrates, mostly due to commercial fisheries. Data on incidental capture is sparse, but it is estimated that about 50% of reported global catches of elasmobranchs are from bycatch. Elasmobranchs are captured in a variety of fishing gear throughout the world. One promising strategy to minimize incidental catches is the release of live sharks and rays. However, so far, no critical analysis had been carried out to assess the importance of release as a measure to mitigate the impacts of bycatch. Results indicated that despite onboard releases being cited in Plans of Action (along ZEEs) and recommendations/regulations of Regional Fisheries Management Commissions (in international waters), this measure is treated as secondary and has voluntary adherence, which can significantly reduce its efficiency. Moreover, among the Best Fishing Practice Manuals currently available, although release is cited as a priority, most of them do not consider the dynamics of the location/fishing modality for which it was developed. A change on how release is perceived is needed to prioritize this conservation strategy, as well as its potential as a social tool to reduce the impacts of bycatch on sharks and rays. [ABSTRACT FROM AUTHOR]

The tiger shark (Galeocerdo cuvier) has been relatively well assessed concerning biology and ecology aspects in both Atlantic and Pacific North America and in Caribbean waters. The amount of data in these regions has led to the species protection under capture quotas and with the creation of sanctuaries. The reality in developing countries, however, is the exact opposite, with scarce information on the species in the southern hemisphere, namely South American and African waters. In these regions, protection measures are insufficient, and studies on tiger shark biology and ecology are scarce, significantly hindering conservation and management efforts. Thus, the aim of this study was to compile scientific literature on the tiger shark in the South Atlantic and discuss the impact of these data (or lack thereof) distributed within a total of ten research categories for guiding management plans. In total, 41 scientific publications on different G. cuvier biology and ecology aspects were obtained. The most studied topics were Feeding Ecology (n = 12), followed by Human Interactions (n = 8), and Movements and Migration (n = 7). Northeastern Brazil (Southwest Atlantic) was the most researched area, probably due to the higher coastal abundance of tiger sharks in this area, alongside a high number of recorded attacks, justifying funding for studies in the region. No studies carried out in other South American or African countries were found. It is important to mention that even though some research topics are relatively well covered, a severe knowledge gap is noted for risk assessments and fisheries management, with a proposition for the implementation of sanctuaries noted. This is, however, particularly worrisome, as the South Atlantic is mostly unexplored in this regard for tiger sharks. It is also important to note how different the attention given to this species is in the North Atlantic when compared to the South region. Lastly, we highlight that the existence of sub-populations, the lack of migratory corridors geographically connecting distinct areas used by the species, and the lack of fisheries statistics on tiger shark landings, all increase the vulnerability of this species in the South Atlantic. [ABSTRACT FROM AUTHOR]

Trophic ecology studies on predator–prey interactions reveal insights into ecological communities and help understand a species' role in the food web by contributing to improved fisheries management and conservation capabilities. Understanding the ecological role of overexploited and endangered predators is essential to deciphering how their feeding behaviour influences food web dynamics. In this study, the authors investigated the feeding behaviour of the common and IUCN‐listed Near Threatened (NT) thornback ray Raja clavata, using carbon and nitrogen stable isotope and stomach content analysis (SCA). It has recently suffered an 87% decline in reported catches from the Sea of Marmara within the last decade. These results show that thornback ray mainly feeds on teleost species, except in summer, with both methods showing this species changes its diet ontogenetically by SCA. This ontogenetic diet shift was at lengths 40–50 cm by changing group preferences from Crustacea to Teleostei. MixSIAR results showed that both adult and juvenile individuals of R. clavata feed mainly on the crustaceans, but the contribution of teleosts represented by Trachurus sp. was very low (<15%). The trophic position increased total length and was higher than other batoid species in the Sea of Marmara. [ABSTRACT FROM AUTHOR]

Although sharks have a fundamental role in maintaining the balance of aquatic ecosystems, exerting a great influence on lower levels of the food chain, their populations are declining worldwide due, to a large extent, to overfishing. Of the 64 species registered in Ecuador, from January to December 2019, 19 species were recorded in Manta from the 15,455 captured individuals, with the family Carcharhinidae being the most abundant in the catches (69.4%), and the most abundant species was Prionace glauca (57.9%). Regarding threatened species, such as Carcharhinus longimanus, Sphyrna lewini, and Sphyrna zygaena, a greater presence of immature specimens was observed in landings. However, information on the composition and biological aspects of shark species in the Ecuadorian Pacific is very scarce. Therefore, research on the characteristics of life history (age, growth, and maturity) are of utmost importance for the stock assessments that are being exploited, especially in developing countries, where this information is lacking, causing inadequate management of fishery resources. [ABSTRACT FROM AUTHOR]

Understanding the population dynamics of highly mobile, widely distributed, oceanic sharks, many of which are overexploited, is necessary to aid their conservation management. We investigated the global population genomics of tiger sharks (Galeocerdo cuvier), a circumglobally distributed, apex predator displaying remarkable behavioral versatility in its diet, habitat use (near coastal, coral reef, pelagic), and individual movement patterns (spatially resident to long-distance migrations). We genotyped 242 tiger sharks from 10 globally distributed locations at more than 2000 single nucleotide polymorphisms. Although this species often conducts massive distance migrations, the data show strong genetic differentiation at both neutral (F ST = 0.125–0.144) and candidate outlier loci (F ST = 0.570–0.761) between western Atlantic and Indo-Pacific sharks, suggesting the potential for adaptation to the environments specific to these oceanic regions. Within these regions, there was mixed support for population differentiation between northern and southern hemispheres in the western Atlantic, and none for structure within the Indian Ocean. Notably, the results demonstrate a low level of population differentiation of tiger sharks from the remote Hawaiian archipelago compared with sharks from the Indian Ocean (F ST = 0.003–0.005, P < 0.01). Given concerns about biodiversity loss and marine ecosystem impacts caused by overfishing of oceanic sharks in the midst of rapid environmental change, our results suggest it imperative that international fishery management prioritize conservation of the evolutionary potential of the highly genetically differentiated Atlantic and Indo-Pacific populations of this unique apex predator. Furthermore, we suggest targeted management attention to tiger sharks in the Hawaiian archipelago based on a precautionary biodiversity conservation perspective. [ABSTRACT FROM AUTHOR]

Copyright of Neotropical Ichthyology is the property of Neotropical Ichthyology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The age and growth of subtropical populations of the Brazilian and Caribbean sharpnose sharks (Rhizoprionodon lalandii and R. porosus respectively) were determined by combining direct and indirect ageing methods, maximising the use of available information. Using vertebrae ageing for R. lalandii , the theoretical maximum length L ∞ and growth coefficient k were 661.9 mm and 1.14 year–1 for males and 751.7 mm and 0.59 year–1 for females. Vertebrae were not sampled for R. porosus. Values of L ∞ and k from electronic length–frequency analyses (ELEFAN) were 762 mm and 0.71 year–1 for male R. lalandii , 791 mm and 0.67 year–1 for female R. lalandii , 1040 mm and 0.41 year–1 for male R. porosus and 1165 mm and 0.31 year–1 for female R. porosus. Growth during the first year of life in relation to birth size was 80.3% for R. lalandii and 55% for R. porosus. Both species exhibit rapid growth, primarily in the first year of life. The growth estimates for R. lalandii and R. porosus are even faster than those reported in previous studies from tropical populations. This study estimated the age and growth parameters of two small coastal shark species for the first time in subtropical waters; unlike most sharks, both species exhibited very fast growth. Considering that these species are the most captured sharks in the study area, the results are crucial for fishery management and for the evaluation of the vulnerability status of the two species. [ABSTRACT FROM AUTHOR]

Ray species have been globally threatened due to high fishing pressure and habitat loss. In southern Brazil fisheries, despite many ray species are protected by law and usually non-targeted species, they are captured along with commercially important species. However, as in all of Brazil, there is evidence that rays are consumed, that is, there is a demand for meat from these animals, which intensifies the risk of extinction. Marine ethnobiology is an alternative approach to better understand these organisms, considering the traditional empirical knowledge of fishers and local communities. Our objective is to evaluate the knowledge of local residents, fishers, and tourists about the occurrence, distribution, reproduction, and feeding of ray species and also ray consumption among them. We hypothesized that fishers and locals have a deeper ecological knowledge about rays than tourists, and fishers should know more than residents. Individual interviews were conducted for three consecutive days at Armação beach, Florianópolis, Brazil. We asked people about ray biology and ecology based on questionnaires. Each respondent was categorized into three groups: fishers, locals, and tourists; and ranked according to an index of ecological knowledge of rays. The fishers had greater knowledge about rays, followed by residents and tourists. Additionally, fishers and locals consume rays, even the trade is prohibited locally, evidencing the need for legal enforcement. The fishers' knowledge may be essential for management of fish stocks, contributing to sustainable fishing and species conservation. In contrast, the tourists' lack of knowledge evidences the need to raise awareness of these animals. [ABSTRACT FROM AUTHOR]

Historically, Brazilian fisheries management has not considered the knowledge of fish taxonomy from within fishing communities. This study points out processes of recognition, classification and nomenclature of sharks achieved by fishermen from South Bahia, Brazil. Data were obtained through semistructured interviews visually stimulated by exhibiting images of 30 species of elasmobranch fishes. Regionally, elasmobranch species are inserted into the folk taxon called "leather fishes" and in a category known as "cação" (shark) family. In addition to hierarchical classification, the fishermen organize shark species by adopting an ethnodimorphic and sequential model based on ethnoontogeny. Ethnodiagnostic characteristics are mainly related to the morphology, ecology and even physiology of a species. A total of 144 epithets is recorded, with a mean value of 4.8 ethnospecies for each scientific correspondent. Richness of vernacular names impedes species-specific information gathering regarding shark landings if fisher knowledge is not considered and applied in the improvement of fisheries data. Thus, this study encourages the employment of fishermen as parataxonomists in order to assist in the identification of sharks to specific levels. This study further emphasizes the potential of using ethnotaxonomic knowledge of fishing communities in initiatives related to participative management of shark fisheries in developing countries. [ABSTRACT FROM AUTHOR]

Isopisthus parvipinnis, commonly known as "bigtooth corvina", is a marine estuarine‐dependent fish captured in the southeast and south Brazilian coast as bycatch of the shrimp fishery. This work used the sagittae morphology as a tool to primarily study the population structure of I. parvipinnis between São Paulo and Santa Catarina states (23ºS to 26.9ºS) in Brazil. Secondly, it intended to verify the existence of morphological alterations over time, by comparing otoliths of fish captured in 1975 and 2018/2019. Otolith shape analyses were performed in individuals ranging from 66 to 139 mm of total length, obtained from historical (1975) and present catches (2018/2019) in the shallow coastal areas off North of São Paulo (NSP), Centre of São Paulo (CSP), South of São Paulo (SSP), Paraná (PR) and Santa Catarina (SC). Otoliths were analyzed using shape indices (SIs), elliptical Fourier descriptors (EFDs) and both tools combined. Morphological variations among locations and between years were tested using uni and multivariate statistics. Data showed regional differences in the otolith shape analysis over the years. Samples from 1975 presented an overall low reclassification rate (43%), with a high overlap of individuals among locations, suggesting the existence of a single group. Differently, samples from 2018/2019 discriminated four distinct spatial units with a good overall reclassification (74%): group 1 ‐ NSP; group 2 ‐ CSP; group 3 ‐ SSP + PR; and group 4 ‐ SC. The hereby data suggests regional changes at long term in the population dynamics of I. parvipinnis, from a single panmictic population in the past to a metapopulation structure in the present days, with consequences for the rational and sustainable management of the fishery. However, once it was the first evaluation of the population structure of I. parvipinnis, it is highly recommended to use complimentary phenotypic and/or genetic approaches to corroborate the hereby observed findings. [ABSTRACT FROM AUTHOR]

Sharks developed life history traits that make them susceptible to overfishing. This is, in turn, a risk for extinction, and several species are affected. The high price of shark fins in the international trade has triggered the widespread capture of sharks at unsustainable levels, prompting illegal and unethical practices, such as finning. To address these concerns, the present study aimed to identify species composition using molecular techniques based on DNA barcoding and DNA polymorphism on samples taken from illegal shark fin seizures conducted by the Federal Environmental Agency of Brazil. A species-specific DNA-based identification from three finning seizures in Brazil found at least 20 species from 747 shark fins, some of which were identified as endangered and protected under Brazilian legislation, while others were representative of restricted catches, according to Appendix II of CITES. In the seizure from Belém, 338 fins were identified as belonging to at least 19 different species, while in the seizure from Natal 211, fins belonging to at least 8 different species were identified. Furthermore, 198 fins from Cananéia were identified through PCR-Multiplex as belonging to Isurus oxyrinchus. These results raise concerns about the environmental and socioeconomic effects of finning on developing countries. Furthermore, this study represents the first finning evaluation from Brazil in the Southwest Atlantic, highlighting the importance of developing policies aimed toward restricting and regulating the shark trade and detecting IUU fisheries and illegal trade of endangered species, mainly in developing countries, where fisheries management, surveillance, and species-specific fisheries catch data are often sporatic. [ABSTRACT FROM AUTHOR]

The age and growth of three endemic threatened guitarfish species were analysed using vertebrae of Pseudobatos horkelii, P. percellens and Zapteryx brevirostris. Edge and marginal‐increment analyses were used to evaluate the periodicity of the formation of the band‐pairs, suggesting deposition of one band‐pair per year, from late winter to late spring. The von Bertalanffy growth model was used to describe the growth of these species with the following parameters, for pooled sexes: P. horkeliiL∞ = 126.93, k = 0.19 and t0 = −1.51; P. percellensL∞ = 109.31, k = 0.16 and t0 = −1.78; Z. brevirostrisL∞ = 60.37, k = 0.24 and t0 = −1.42. Our results are essential to understanding the resilience and vulnerability of these species to harvest, which can contribute to management and conservation actions of these species. [ABSTRACT FROM AUTHOR]

The biogeography and conservation of elasmobranch species was increasingly addressed in the recent past, but the southwestern Atlantic Ocean fauna is still one of the least studied. Reliable delimitation of the distribution range of species is fundamental to conservation and development of fisheries management strategies. A recent molecular study of the cryptic Aetobatus narinari species complex restricted that species to western and eastern coasts of the New World. However, the current distribution of A. narinari and phylogenetic relationships within the genus Aetobatus have yet to be clarified, the goal of this phylogeographic analysis. Using mitochondrial and nuclear markers we investigated specimens from the Atlantic coast of Brazil and the Pacific coast of Mexico and related them to previously analyzed specimens from other regions. Our analysis indicates that Aetobatus narinari is present only in the western Atlantic, formed by a single genetic lineage that ranges between Florida and southeastern Brazil, while the Pacific New World lineage is in fact assigned to Aetobatus laticeps. Analysis of divergence times revealed that biogeographic events such as the closure of the Tethys Sea, the formation of the Benguela barrier, and the Isthmus of Panama played major roles in diversification and dispersal of the genus Aetobatus. [ABSTRACT FROM AUTHOR]

Copyright of Neotropical Ichthyology is the property of Neotropical Ichthyology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to graph theory, the frequency distribution of trophic interactions within a food web has deep structural implications, as it can highlight the presence of patterns associated with the web and indicate whether the properties of the web are independent of its size. A hypothesis is that 'small-world' food webs are sensitive to the loss of species with the highest values. Therefore, the present work aimed to evaluate the degree to which a subtropical food web in Southern Brazil displays small-world patterns and their resistance. As part of the assessment, we evaluated the topological redundancy values of species in the food web and then we simulated the exclusion of these species (such as sharks and sea birds), and also the exclusion of high centrality species (such as squids Loligo sp., portunid swimming crabs and the cutlassfish Trichiurus lepturus). The food web showed a 'broad-scale' distribution of connections by node, and a small-world pattern. As expected, a simplification of the network was observed after elimination of some species with high centrality. However, the food web was resistant to the loss of species with low topological redundancy, probably because these species occupy a high trophic level and do not participate in lots of routes within the food web. We highlight however, the importance of the application of multiple analyses to evaluate the importance of components in food webs, and fisheries management plans should consider both species of high centrality values and species with low topological redundancy. [ABSTRACT FROM AUTHOR]

Background: Ecosystem modeling applied to fisheries remains hampered by a lack of local information. Fishers’ knowledge could fill this gap, improving participation in and the management of fisheries. Methodology: The same fishing area was modeled using two approaches: based on fishers’ knowledge and based on scientific information. For the former, the data was collected by interviews through the Delphi methodology, and for the latter, the data was gathered from the literature. Agreement between the attributes generated by the fishers’ knowledge model and scientific model is discussed and explored, aiming to improve data availability, the ecosystem model, and fisheries management. Principal Findings: The ecosystem attributes produced from the fishers’ knowledge model were consistent with the ecosystem attributes produced by the scientific model, and elaborated using only the scientific data from literature. Conclusions/Significance: This study provides evidence that fishers’ knowledge may suitably complement scientific data, and may improve the modeling tools for the research and management of fisheries. [ABSTRACT FROM AUTHOR]

Understanding the trophic interactions and the position of species within a foodweb is crucial if we want to understand the dynamics of marine communities and the impact individual components of the community have on trophic network compartments. Recent studies have indicated sharks and rays are important elements within foodwebs. In this study, we evaluated the ecological importance of sharks and rays in a subtropical ecosystem off the coast of southern Brazil by using topological analyses. We tested the hypotheses that some elasmobranchs can be considered key elements within the foodweb, and that large predators have topological importance (act as keystones), so that, when large predators are excluded, mesopredator elasmobranchs occupy higher topological positions. Our results indicate that Galeocerdo cuvier, Carcharhinus obscurus, Carcharias taurus, Sphyrna lewini and S. zygaena are species with large ecological function values and may exert a powerful influence over lower levels. These issues need to be considered by conservation and fishery management groups since it appears that ecosystem integrity may be compromised by reductions in the populations of large predators. Carcharhinus obscurus, S. zygaena and Zapteryx brevirostris were found to be the elasmobranchs with largest values of centrality, and can, therefore, be considered key elements in the topological structure. [ABSTRACT FROM PUBLISHER]

Simple Summary: Sharks, rays, and skates are increasingly being recognized as endangered due to their life-history characteristics, fishing pressure, and habitat degradation. The thornback ray Raja clavata is one of the most commercially important skates in the seas of Northwest Europe. However, due to a lack of biological knowledge about this species in Azorean waters, the types of stock evaluations that can be performed are restricted. This study expands current knowledge on vertical distribution, size-frequency distributions, growth patterns, sex ratios, mortality rates, and reproduction of this species, and provides a baseline for further fishing monitoring. Elasmobranchs are globally recognized as vulnerable due to their life-history characteristics, fishing pressure, and habitat degradation. Among the skates and rays caught by commercial fisheries, the thornback ray Raja clavata is one of the most economically important in Northwest European seas. However, the scarcity of biological knowledge about this species in Azorean waters has limited the stock assessment types that can be conducted. To improve information on its habitat preferences, spatial distribution and movement pattern, growth, sex ratio, mortality, and reproduction, as well as to investigate long-term changes in abundance and size, this study analyzed approximately 25 years of fishery-dependent and independent data from the Azores. Raja clavata was mainly caught at depths up to 250 m. Most of the tagged fish were recaptured near the release point. A larger–deeper trend was found, and females were larger and more abundant than males. Life-history parameters showed that R. clavata has a long lifespan, large size, slow growth, and low natural mortality. The sustainability of its population is of concern to fisheries management and, while our findings suggested a relatively healthy stock in the Azores, a thorough increase in data quality is required to better understand the stock condition and prevent overexploitation. [ABSTRACT FROM AUTHOR]

Today, elasmobranchs are one the most threatened vertebrate groups worldwide. In fact, at least 90% of elasmobranch species are listed in the International Union for Conservation of Nature (IUCN) Red List, while more than 40% are data-deficient. Although these vertebrates are mainly affected by unsustainable fishery activities, bycatch is also one of the major threats to sharks and batoids worldwide, and represents a challenge for both sustainable fishery management and for biodiversity and conservational efforts. Thus, in this study, DNA barcode methodology was used to identify the bycatch composition of batoid species from small-scale industrial fisheries in the southwest Atlantic and artisanal fisheries from southeast Brazil. A total of 228 individuals belonging to four Chondrichthyes orders, seven families, and at least 17 distinct batoid species were sequenced; among these individuals, 131 belonged to species protected in Brazil, 101 to globally threatened species, and some to species with trade restrictions provided by Appendix II of the Convention on International Trade in Endangered Species (CITES). These results highlight the impacts on marine biodiversity of bycatch by small-scale industrial and unmanaged artisanal fisheries from the southwest Atlantic, and support the implementation of DNA-based methodologies for species-specific identification in data-poor fisheries as a powerful tool for improving the quality of fisheries' catch statistics and for keeping precise bycatch records. [ABSTRACT FROM AUTHOR]