Elasmobranch Landings Malvan, India 2018-20

This data was collected by Ms. Trisha Gupta from Malvan, central west coast of India in the state of Maharashtra. It forms the basis for analysis of catch composition in Malvan for the study titled 'Insights from catch composition and historical records of elasmobranchs in the Malvan fishery on the central west coast of India' which has been accepted for publication in the Journal of Fish Biology, 2023. DOI and link https://doi.org/10.1111/jfb.15416 - please do cite this paper and the Figshare DOI if this data is used for other studies or research work. This would be highly appreciated.Landing surveys were conducted over three sampling periods: February to May 2018, October 2018 to May 2019 and from December 2019 to March 2020. For the first two periods, sampling was conducted thrice a week on alternate days, while for the last period sampling was once a week on a randomly selected day. January–May constituted the pre-monsoon season and August–December constituted the post-monsoon season. Both morning and evening auctions were surveyed and all boats with elasmobranchs were sampled.Since on any given day only a fraction of the boats (50% on average) would land their catch for auction and due to the smaller scale of fisheries in Malvan, as compared to other bigger ports in India, all boats that landed elasmobranchs could be sampled. About 10% (by abundance) of each elasmobranch taxon was further sampled for biological data such as sex, maturity stage and size (total length TL for sharks and guitarfish, disc width DW for rays). Further through informal interviews data on fishery factors such as gear, depth, effort, time etc. were collected.

本数据集由印度中西部沿海马哈拉施特拉邦马尔万地区的特里莎·古普塔（Trisha Gupta）女士采集。其为题为《印度中西部沿海马尔万渔场板鳃类（elasmobranchs）渔获组成与历史记录的启示》的研究提供了马尔万地区渔获组成分析的核心数据支撑，该研究已被《鱼类生物学杂志（Journal of Fish Biology）》2023年刊收录，DOI及链接为https://doi.org/10.1111/jfb.15416。若将本数据集用于其他研究或科研工作，请务必引用该论文及Figshare的DOI，我们将不胜感激。
本次上岸渔获调查共开展三轮采样时段：2018年2月至5月、2018年10月至2019年5月，以及2019年12月至2020年3月。前两轮采样为每周三次隔日采样，第三轮采样为每周一次随机择日采样。其中1月至5月为季风前季节，8月至12月为季风后季节。调查覆盖每日早晚两场拍卖活动，所有载有板鳃类的渔船均纳入采样范围。
由于单日仅有部分渔船（平均占比50%）会靠岸拍卖渔获，且相较于印度其他大型港口，马尔万渔场规模较小，因此所有载有板鳃类的靠岸渔船均可完成完整采样。
针对每个板鳃类类群，按丰度抽取约10%的个体开展生物学数据采集，内容包括性别、成熟阶段及体长：鲨鱼和犁头鳐测量全长（total length, TL），鳐类测量体盘宽（disc width, DW）。此外，通过非正式访谈收集了渔具类型、作业水深、作业时长等渔业相关因子的调研数据。