Catch composition and life history characteristics of sharks and rays (Elasmobranchii) landed in the Andaman and Nicobar Islands, India

Abstract

Detailed information on shark and ray fisheries in the Andaman and Nicobar Islands, India are limited, including information on the diversity and biological characteristics of these species. We carried out fish landing surveys in South Andamans from January 2017 to May 2018, a comprehensive and cost-effective way to fill this data gap. We sampled 5,742 individuals representing 57 shark and ray species landed from six types of fishing gears. Of the 36 species of sharks and 21 species of rays landed, six species of sharks ( Loxodon macrorhinus , Carcharhinus amblyrhynchos , Sphyrna lewini , C . albimarginatus , C . brevipinna , and Paragaleus randalli) comprised 83.35% of shark landings, while three species of rays ( Pateobatis jenkinsii , Himantura leoparda and H . tutul ) comprised 48.82% of ray landings, suggesting a species dominance in the catch or fishing region. We provide insights into the biology of species with extensions in maximum size for seven shark species. Additionally, we document an increase in the known ray diversity for the islands and for India with three previously unreported ray species. We found that amongst sharks, mature individuals of small-bodied species (63.48% males of total landings of species less than 1.5 m total length when mature) and immature individuals of larger species (84.79% males of total landings of species larger than 1.5 m total length when mature) were mostly landed; whereas for rays, mature individuals were predominantly landed (80.71% males of total landings) likely reflecting differences in habitat preferences along life-history stages across species and fishing gear. The largest size range in sharks was recorded in landings from pelagic longlines and gillnets. Further, the study emphasizes the overlap between critical habitats and fishing grounds, where immature sharks and gravid females were landed in large quantities which might be unsustainable in the long-term. Landings were female-biased in C . amblyrhynchos , S . lewini and P . jenkinsii , and male-biased in L . macrorhinus and H . leoparda , indicating either spatio-temporal or gear-specific sexual segregation in these species. Understanding seasonal and biological variability in the shark and ray landings over a longer study period across different fisheries will inform future conservation and fishery management measures for these species in the Andaman and Nicobar Islands.

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

“…Bangladesh has proven to be a high biodiverse region regarding elasmobranchs (confirmed 111 species in the annotated checklist) compared to neighbouring countries. Elasmobranch species richness recorded in Bangladeshi waters is higher than that of other Indian Ocean countries and regions including Bay of Bengal such as the Arabian Gulf, which has 43 shark species [ 95 ], Sri Lanka (92- >100 elasmobranchs) [ 96 , 97 ], Maldives (51 elasmobranchs) [ 98 ] and Andaman and Nicobar Islands reporting 57 species [ 99 ]. Elasmobranch diversity in Bangladesh is also possibly higher than in Thailand (145 elasmobranchs) [ 100 ].…”

Integrating long‐term citizen science data and contemporary artisanal fishery survey data to investigate recreational and small‐scale shark fisheries in Kenya

“…The high variety of shark species caught, especially in SSF, is probably due to the non-specificity of fishing gears used by small-scale fishers (Tyabji et al, 2020). Shark catches occurred in seven of the 17 gear types recorded in the Kenyan SSF, with shark species composition varying substantially among gears.…”

Shark and ray research in India has low relevance to their conservation

“…The policies that exist include the protection of 10 species under the Wildlife (Protection) Act (WLPA) in 2001, and the prohibition of shark fin exports in 2015 (Kizhakudan et al, 2015). These policies may not be entirely driven by scientific information; for instance, most of the 10 species protected under the WLPA are very rarely caught in fisheries, and a few of these species do not actually occur in Indian waters (Akhilesh et al, 2014;Tyabji et al, 2020). While poorly framed policies can be attributed to multiple factors, having a body of scientific research that addresses policy-relevant questions to draw on can aid in improving policy making.…”