Evaluating artisanal fishing of globally threatened sharks and rays in the Bay of Bengal, Bangladesh

Sharks and rays are at risk of extinction globally. This reflects low resilience to increasing fishing pressure, exacerbated by habitat loss, climate change, increasing value in a trade and inadequate information leading to limited conservation actions. Artisanal fisheries in the Bay of Bengal of Bangladesh contribute to the high levels of global fishing pressure on elasmobranchs. However, it is one of the most data-poor regions of the world, and the diversity, occurrence and conservation needs of elasmobranchs in this region have not been adequately assessed. This study evaluated elasmobranch diversity, species composition, catch and trade within the artisanal fisheries to address this critical knowledge gap. Findings show that elasmobranch diversity in Bangladesh has previously been underestimated. In this study, over 160000 individual elasmobranchs were recorded through landing site monitoring, comprising 88 species (30 sharks and 58 rays) within 20 families and 35 genera. Of these, 54 are globally threatened according to the IUCN Red List of Threatened Species, with ten species listed as Critically Endangered and 22 species listed as Endangered. Almost 98% juvenile catch (69–99% for different species) for large species sand a decline in numbers of large individuals were documented, indicating unsustainable fisheries. Several previously common species were rarely landed, indicating potential population declines. The catch pattern showed seasonality and, in some cases, gear specificity. Overall, Bangladesh was found to be a significant contributor to shark and ray catches and trade in the Bay of Bengal region. Effective monitoring was not observed at the landing sites or processing centres, despite 29 species of elasmobranchs being protected by law, many of which were frequently landed. On this basis, a series of recommendations were provided for improving the conservation status of the elasmobranchs in this region. These include the need for improved taxonomic research, enhanced monitoring of elasmobranch stocks, and the highest protection level for threatened taxa. Alongside political will, enhancing national capacity to manage and rebuild elasmobranch stocks, coordinated regional management measures are essential

Opportunities and challenges in value chain analysis for sustainable management of sharks and rays

Studies on elasmobranch trade have often focused on a single commodity, shark fins. Such a narrow focus can result in an incomplete understanding of the socio-cultural importance of sharks, limiting discussion on the range and efficacy of potential management interventions. Assessments must be performed across the value chain from fisher to retail vendor to better conserve vulnerable elasmobranch species, offering a broader view of capture, use, and trade. Here, we collate insights from shark value chain assessments conducted in eight countries (Mexico, Peru, Guinea-Bissau, India, Bangladesh, Sri Lanka, Indonesia and Fiji) spanning five continents. Approaches and processes implemented in a shark value chain analysis (VCA) were reviewed to: (1) understand better approaches and tools and (2) collate shared experiences. Our results demonstrate that VCAs broaden the outlook of fishery and trade assessments when capturing a more comprehensive range of economic and socio-cultural aspects (e.g., livelihoods, cultural use of commodities) of trade in all shark commodities. Time invested in various components of assessments produced different outcomes, with considerable returns from stakeholder selection, survey design, and assessor/stakeholder relationship building. Contrastingly, results demonstrated that efforts in communication with stakeholder groups and policymakers could be further streamlined to focus on key results using a variety of communication formats. Outcomes from this study offer guidance to those embarking on shark VCAs, facilitating improving the assessment process and outcomes

Towards sustainable management of sharks and rays in the Bay of Bengal, Bangladesh

Elasmobranchs (hereafter referred to as 'sharks and rays') have declined in landings, species diversity in catch and population size in various regions of the world due to human-driven pressures, primarily unsustainable fishing. Combined with their life history characteristics, these pressures make them extremely vulnerable to ongoing threats. Incidental shark and ray catches (or bycatch) are substantial and essential livelihood options for food security in developing countries. Considerable shark and ray catches and traded products come from countries marked by the perpetual poverty of coastal communities that depend highly on artisanal fisheries. This doctoral research takes the case study of shark and ray fisheries in Bangladesh to understand the key issues and to investigate potential practical conservation and management actions for sharks and rays from a global south perspective. Artisanal fisheries in the Bay of Bengal of Bangladesh contribute to the worldwide fishing pressure on sharks and rays. However, it is also one of the most data-poor regions of the world. Here, the fisheries are heterogeneous and complex, and socio-economic dependence is high, making it extremely challenging to balance fish protection and fishers' livelihoods. I addressed the lack of critical data on sharks and ray fisheries in Bangladesh, considering species diversity, fishery characteristics and trade in detail through a combination of field surveys, observations, and interviews. I also evaluated the risks of different shark and ray species against contemporary fishing pressures by assessing species’ ‘area of exposure’ to artisanal fishing. Key findings include the high diversity of sharks and rays within the artisanal landings. However, decreased diversity, abundance, and size of caught specimens was also revealed, attributed to increased fishing intensity, and an accessible market. Furthermore, most southwestern and southcentral shallow waters were found to have a high risk of species encounter with artisanal fisheries; thus, spatiotemporal management needs to be prioritised, particularly in these areas. Gillnet fishing was found to be the most significant threat to bycatch sharks and rays due to its three- dimensional spatial scale and fishing tactics. While the catch and trade of most sharks and rays are regulated under Bangladesh's law, this study revealed an absence of bycatch mitigation strategies and no incentives for fishers to adhere to current laws leading to non- compliance. Likely causes of non-compliance include a dearth of awareness, alternative livelihoods, technical facilities, and the complex nature of the fisheries. Lack of opportunities and information to adhere to regulations and increased enforcement (only) has led to conflicts, non-compliance and unwillingness to report catches by fishers and traders. An imbalanced power and financial structure between actors (e.g., fishers, traders) were also revealed, with actors accessing unequal benefits from the market. Impediments for implementing conservation measures by low-access actors (e.g., fishers) with limited decision-making power or resources were evident. Fishers reported several socio-ecological, technical, and enforcement issues (e.g., policing instead of meaningful monitoring and punitive measures without facilitating compliance). Crucial interventions to address the unsustainability problem include improved taxonomic research, enhanced monitoring of stocks, meaningful protection for threatened taxa and safeguarding fishers to improve compliance. Although legal measures are necessary, this cannot be the only tool to mitigate the significant cumulative effects of fishing on these species. Reducing the risk from fisheries requires pre-emptive measures that minimise the interaction of species with fisheries through improved and better- informed careful management. Encouraging and facilitating the engagement of fishers in science (data collection), local governance (policy-making), and field implementation (bycatch mitigation) is vital, acknowledging that adequate time and resources will be required to change practices. A key recommendation is to focus management efforts in specific coastal locations (i.e., evidence-based spatiotemporal management) while prioritising high-risk species groups benefitting multi-taxa conservation. These interventions must be rooted in sustainable approaches and co-designed with fishers, with appropriate training and resources available

Mitigating elasmobranch fin trade: A market analysis for made-to-measure interventions

The unsustainable trade in elasmobranch products, particularly fins, contributes to the decline of elasmobranch populations worldwide. Designing and implementing context-appropriate solutions to mitigate unsustainable trade requires a thorough analysis of markets. Here we assess the market component of the elasmobranch fin trade in the Bay of Bengal, Bangladesh, using a framework designed to analyse wildlife markets. Using a mixed-method approach, we characterised the market to identify the components contributing to unsustainable practices. By-catch retention levels were high leading to the development of a solid market. Trade on fins was prevalent due to a high price, lack of awareness, actors' limited ability to adhere to regulations, and no strategies and incentives to limit fishing mortality. An imbalanced power and financial structure between actors were revealed, with some actors accessing unequal benefits from the market. Impediments for adopting conservation measures by low-access actors (e.g., fishers) with limited decision-making power or resources were evident. We also identified challenges to enforcement primarily due to limited reporting and issues identifying species and products. Fishers noted several socio-ecological, technical, and enforcement issues (e.g., policing instead of meaningful monitoring, punitive measures without facilitating compliance), that will require adequate time and resources to change practices. Lack of opportunities and information to adhere to regulations and increased enforcement has led to conflicts, non-compliance and unwillingness to report catches. The study has significantly strengthened the current understanding of Bangladesh's complex elasmobranch product market while highlighting critical knowledge gaps that must be addressed to inform and improve management decisions. Based on the findings, we recommend targeted actions to respond to the current market for mitigating elasmobranch product trade and moving towards establishing sustainable and ethical trade. Our work has both regional and global significance, given the role of the Bay of Bengal nations in the worldwide elasmobranch product market

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

Fishers' tales—Impact of artisanal fisheries on threatened sharks and rays in the Bay of Bengal, Bangladesh

Funder: Bangladesh Fisheries Research Institute; Id: http://dx.doi.org/10.13039/501100008229Funder: Save Our Seas Foundation; Id: http://dx.doi.org/10.13039/501100007665Funder: National Geographic Photo Ark ZSL EDGEFunder: Natural Environment Research Council; Id: http://dx.doi.org/10.13039/501100000270Funder: Bangabandhu Overseas Scholarship 2019, University of Dhaka, BangladeshAbstract: Increasing fishing pressure has negatively impacted elasmobranch populations globally. Despite high levels of historical and current fishing pressure, the Bay of Bengal region remains data‐poor. Focusing on Bangladesh, we conducted a socio‐ecological study to characterize elasmobranch fisheries and evaluate their impact on threatened species. The results demonstrate that several globally threatened elasmobranch species are frequently captured, and some of them have experienced substantial population declines (e.g., wedgefishes, sawfishes, large carcharhinid sharks) over the past decade. A decrease in elasmobranch diversity, abundance, and size of caught specimens was also reported, which was attributed to increased fishing intensity, destructive practices (e.g., bottom trawling), and an accessible elasmobranch market. While catch and trade of more than 90 elasmobranchs are regulated under Bangladesh's law, non‐compliance is widespread. Likely causes include a dearth of awareness, practical alternative livelihoods, and technical facilities, and the complex nature of the fisheries. Encouraging and facilitating the engagement of fishers in science (data collection), local governance (policy‐making), and field implementation (bycatch mitigation) is vital. These interventions must be rooted in sustainable approaches and co‐designed with fishers, with appropriate training available. Development of this work through enhanced engagement with fishers has the potential to transform the elasmobranch fishery situation in Bangladesh and could be used as a model for data‐poor regions

Brevitrygon Last, Naylor & Manjaji-Matsumoto 2016

Genus Brevitrygon Two species within the genus Brevitrygon (B. walga and B. imbricata) have previously been reported in Bangladesh (Hoq et al. 2011). This study confirmed an additional eight specimens morphologically consistent with Brevitrygon heterura (Figure 2).Published as part of Haque, Alifa Bintha, White, William T., Cavanagh, Rachel D., Biswas, Aparna Riti & Hossain, Nazia, 2021, New records of elasmobranchs in the Bay of Bengal, Bangladesh: further taxonomic research is essential, pp. 211-230 in Zootaxa 5027 (2) on page 217, DOI: 10.11646/zootaxa.5027.2.4, http://zenodo.org/record/544823

Mobulidae Gill 1893

Family Mobulidae Two species of Mobula have previously been recorded from Bangladesh; Mobula mobular and M. kuhlii ( Hoq et al. 2011; Roy et al. 2014a ). In this study, M. birostris, M. tarapacana, M. eregoodoo and M. thurstoni (Figure 13) were recorded following examination of 97 mobulid specimens. Genetic analysis confirmed species identification for M. tarapacana, M. kuhlii and M. mobular, and the presence of either M. alfredi or M. birostris, but the NADH2 sequences alone cannot distinguish between these two species due to overlapping sequence polymorphism (G. Naylor, unpubl. data). This study confirms the presence of at least six mobulid species in Bangladesh; M. alfredi or M. birostris, M. eregoodoo, M. kuhlii, M. mobular, M. tarapacana and M. thurstoni where M. thurstoni has been reported for the first time with possible presence of M. alfredi.Published as part of Haque, Alifa Bintha, White, William T., Cavanagh, Rachel D., Biswas, Aparna Riti & Hossain, Nazia, 2021, New records of elasmobranchs in the Bay of Bengal, Bangladesh: further taxonomic research is essential, pp. 211-230 in Zootaxa 5027 (2) on page 223, DOI: 10.11646/zootaxa.5027.2.4, http://zenodo.org/record/544823

Triakidae J.E.Gray 1851

Family Triakidae Three houndshark species have been previously recorded from Bangladesh, i.e. Mustelus manazo, M. mosis and Iago garricki (Hoq et al. 2011; Habib et al. 2020).A total of 31 specimens of a second species of the Iago omanensis complex (which includes the poorly defined I. mangalorensis, if considered valid (Sen et al. 2020; Weigmann 2016; Maduna & Bester-van der Merwe 2017)) were recorded in this study. There is a possibility the recorded Iago sp. could be a new species to science as two separate species (Iago sp. A and Iago sp. B) have been theorised to be present in the Indian waters (Bineesh et al. 2017). This species is tentatively identified as Iago cf. omanensis (Figure 18) pending further taxonomic investigation. It brings the total number of triakid species in Bangladesh to four, with the taxonomy of the Mustelus species in this region being investigated by one of the authors (WW).Published as part of Haque, Alifa Bintha, White, William T., Cavanagh, Rachel D., Biswas, Aparna Riti & Hossain, Nazia, 2021, New records of elasmobranchs in the Bay of Bengal, Bangladesh: further taxonomic research is essential, pp. 211-230 in Zootaxa 5027 (2) on page 226, DOI: 10.11646/zootaxa.5027.2.4, http://zenodo.org/record/544823

Neotrygon Castelnau 1873

Genus Neotrygon The Neotrygon kuhlii species complex has recently been expanded (Last et al. 2016). These taxonomic revisions, however, did not consider Bay of Bengal specimens in detail. To date, two species have been recorded from Bangladesh; N. indica and N. kuhlii (Haque et al. 2019a; Hoq et al. 2011). In this present study, a total of 649 specimens were examined, and five sampled for genetic analysis. Morphological differences were observed, including the dorsal coloration and tail banding. Several specimens were most consistent with N. caeruleopunctata, but have been preliminarily identified as N. cf. caeruleopunctata (Figure 5) due to possible genetic differences in the Bay of Bengal specimens. It is likely that previous records of N. kuhlii represent this species, with N. kuhlii now considered to occur only from the Solomon Islands, and adjacent island groups (Last et al. 2016a). All genetically sampled specimens were labelled as Neotrygon Bay of Bengal variants.Published as part of Haque, Alifa Bintha, White, William T., Cavanagh, Rachel D., Biswas, Aparna Riti & Hossain, Nazia, 2021, New records of elasmobranchs in the Bay of Bengal, Bangladesh: further taxonomic research is essential, pp. 211-230 in Zootaxa 5027 (2) on page 218, DOI: 10.11646/zootaxa.5027.2.4, http://zenodo.org/record/544823