The scientific literature on the diversity and biological characteristics of sharks and rays from the Andaman and Nicobar Archipelago fishing grounds is scarce and compromised by species misidentifications. We carried out systematic 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. Of the 36 species of sharks and 21 species of rays landed, six species of sharks - Loxodon macrorhinus, Carcharhinus amblyrhynchos, Sphyrna lewini, Carcharhinus albimarginatus, Carcharhinus brevipinna, and Paragaelus randalli dominated landings and comprised 83.35 % of shark landings, while three species of rays were most abundant – Pateobatis jenkinsii, Himantura leoparda and H. tutul, and comprised 48.82 % of ray landings. We report size extensions for seven shark species as well as three previously unreported ray species, increasing the known diversity for the islands and for India. For sharks, mature individuals of small-bodied species (63.48 % males of total landings of species less than 1.5 m total length) and immature individuals of larger species (84.79 % males of total landings of species larger than 1.5 m total length) were mostly landed; whereas for rays, mature individuals were predominantly landed (80.71 % males of total landings) likely reflecting differences in fishing patterns as well as habitat preferences and life history stages across species. Further, juvenile 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 these nuances - the composition and biology of sharks and rays landed in different fisheries seasonally will inform future conservation and fishery management measures for these species in the Andaman and Nicobar Islands.

中文翻译：

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栖息在印度安达曼和尼科巴群岛的鲨鱼和rays（Elasmobranchii）的捕获组成和生活史特征

有关来自安达曼群岛和尼科巴群岛渔场的鲨鱼和rays鱼的多样性和生物学特征的科学文献十分稀少，而且由于物种识别错误而受到损害。我们于2017年1月至2018年5月在南安达曼群岛进行了系统的鱼类着陆调查，这是填补这一数据缺口的一种全面且具有成本效益的方法。我们对代表57种鲨鱼和鱼物种的5,742个人进行了采样。-在36种鲨鱼和21种射线降落，六种鲨鱼的象族macrorhinus，真鲨amblyrhynchos，Sphyrna lewini，真鲨albimarginatus，真鲨brevipinna，和Paragaelus randalli为主着陆和由鲨鱼着陆83.35％，而三个品种的光线最丰富–帕氏青蒿，喜马拉雅山豹和H. tutul，占射线着陆量的48.82％。我们报告了七个鲨鱼种类以及三个以前未报告的射线种类的尺寸扩展，从而增加了这些岛屿和印度的已知多样性。对于鲨鱼，小个体的成熟个体（占总长度小于1.5 m的物种的总体着陆的雄性的63.48％）和较大物种的未成熟个体（对总长度大于1.5 m的物种的总着陆的雄性的84.79％）主要是登陆; 而对于射线，成熟的个体主要着陆（占总着陆率的男性为80.71％），这可能反映了不同种类的捕鱼方式以及生境偏好和生活史阶段的差异。此外，幼鲨和妊娠雌性鱼类大量登陆，这从长远来看可能是不可持续的。着陆点偏向女性C. amblyrhynchos，S。lewini和P. jenkinsii，在L. macrorhinus和H. leoparda中有雄性偏性，表明这些物种中的时空或齿轮特定的性别隔离。了解这些细微差别-季节性降落在不同渔业中的鲨鱼和rays鱼的组成和生物学，将为安达曼和尼科巴群岛的这些物种今后的保护和渔业管理措施提供依据。