Diversity and abundance of mesopelagic fishes along 110°E, south-east Indian Ocean for the 2nd Indian Ocean Expedition (IIOE-2). RV Investigator voyage IN2019_V03 (2019)

Samples were obtained from the RV Investigator from 14 May - June 5, 2019 as part of the 2nd Indian Ocean Expedition (IIOE-2). A total of 20 stations (90 nautical miles apart) from 39.5 deg south to 11.5 deg S along the 110 ?E meridian was sampled during both day and night. The samples were obtained by means of hauls using a EZ multi-net with a 1 m2 mouth area and eight operating nets (500 µm mesh). It was sent down to 500 m depth and oblique hauls discriminating the following depth strata of the water column were taken as the net was retrieved: 500-400, 400-300, 300-200, 200-150, 150-100, 100-50, 50 - 5 m. Each stratum was sampled for about 10 min and the volume of water filtered was obtained via use of an electronically recording flowmeter (mean volume: 486.5 m3). In summary, 273 discrete stratum hauls, covering the upper 500 m of the water column, were made along the 110 deg E transect in the Indian Ocean. After sorting and identification of fish specimens on board, samples were preserved in 10% buffered formalin with borax for later inspection in the laboratory. Voyage details (metadata, projects, other datasets either online or as downloads, publications and reports, events, maps etc) can be accessed at https://www.marine.csiro.au/data/trawler/survey_details.cfm?survey=IN2019_V03 If this data has been used in any products, please acknowledge with the following: We acknowledge the use of the CSIRO Marine National Facility (https://ror.org/01mae9353) in undertaking this research.本数据集的样本采集于2019年5月14日至6月5日期间，由调查船RV Investigator执行，为第二次印度洋探险（IIOE-2）的组成部分。本次调查沿110°E经线布设了共计20个采样站位（站位间距为90海里），采样覆盖范围从南纬39.5°至南纬11.5°，且昼夜时段均开展了采样作业。采样采用口面积为1 m²的EZ多网采样器（EZ multi-net），该设备包含8个网衣，网孔孔径为500 µm。采样时将网具下放至500米水深，在起网过程中按以下水层分层进行斜向拖网采样：500-400米、400-300米、300-200米、200-150米、150-100米、100-50米、50-5米。每个水层的采样时长约为10分钟，通过电子记录式流量计计算过滤水体体积，平均过滤体积为486.5 m³。综上，本次印度洋110°E断面调查共完成273个分层采样拖次，覆盖水体上层至500米水深范围。在船上完成鱼类标本的分拣与鉴定后，样品采用含硼砂的10%缓冲福尔马林溶液进行保存，用于后续实验室分析。 本次航行的详细信息（包括元数据、项目信息、在线/可下载的其他数据集、已发表文献与报告、调查事件、地图等）可通过以下链接获取：https://www.marine.csiro.au/data/trawler/survey_details.cfm?survey=IN2019_V03 若基于本数据集产出任何研究成果，请使用以下致谢表述：本研究使用了澳大利亚联邦科学与工业研究组织（CSIRO）海洋国家设施（https://ror.org/01mae9353）的调查资源，特此致谢。