Fish and invertebrate trawl sampling south and west of Iceland in July 2018

This data set has trawl catch weight and biological measurements from the 2nd leg of the Icelandic part of the International Ecosystem Summer Survey in Nordic Seas (IESSNS). The survey area was from the coast, over the shelf edge and into the deep-water basins south and west of Iceland, defined as IESSNS strata 5, 6, and 12, and stratum boundaries (black solid line) are displayed on attached map "IESSNS 2018.png". The survey period is July 19th to August 1st, 2018, and samples were collected at 34 trawl stations (blue symbol on attached map "IESSNS 2018.png"). A specifically designed scientific trawl, called Multpelt832 (ICES 2013a-b, Valdemarsen et al. 2014) with cod-end mesh size of 50 mm, was used at all 34 stations. Trawl depth ranged from surface (trawl headline in surface) to 400 m depth. All trawl catch is identified to lowest possible taxonomic level, total weight of each species recorded and length of 20-50 specimen per species measured. For blue whiting (Micromesistius poutassou), herring (Clupea harengus), and mackerel (Scomber scombrus) more biological measurements are provided such as weight, sex, maturity, age, liver weight and stomach weight. Each specimen is one row in the data set file. Natantia and Scyphozoa specimen could not be identified to species, hence no individual length measurements are provided but total weight of catch per taxon is provided. For detailed information about the survey see the survey report (Ólafsdóttir and Jónsson 2019). Various information is provided about the trawling operation, weather, position, date and time.

本数据集收录北欧海国际生态系统夏季调查（International Ecosystem Summer Survey in Nordic Seas, IESSNS）冰岛区段第二航次的拖网捕捞重量与生物学测量数据。本次调查区域覆盖沿岸、陆架外缘及冰岛南部与西部的深水盆地，对应IESSNS分层5、6和12，分层边界（黑色实线）详见附件地图"IESSNS 2018.png"。调查时段为2018年7月19日至8月1日，共在34个拖网站位（附件地图"IESSNS 2018.png"中的蓝色标记）采集样本。所有34个站位均使用一款Multpelt832型科研拖网（Multpelt832），其囊网网目尺寸为50 mm，相关技术参数参见ICES 2013a-b、Valdemarsen et al. 2014。拖网作业水深范围为表层（拖网浮纲处于表层）至400米。所有拖网捕获生物均被鉴定至尽可能低的分类阶元，记录各物种的总重量，并测量每个物种20至50号标本的体长。针对蓝鳕（*Micromesistius poutassou*）、大西洋鲱（*Clupea harengus*）和大西洋鲭（*Scomber scombrus*），额外提供体重、性别、成熟度、年龄、肝脏重量及胃重量等更多生物学测量指标。数据集文件的每一行对应一个单个标本。对虾次目（Natantia）和钵水母纲（Scyphozoa）的标本无法鉴定至物种水平，因此未提供单一个体的体长测量数据，但给出了各分类群的总捕捞重量。有关本次调查的详细信息可参阅调查报告（Ólafsdóttir and Jónsson 2019）。数据集还包含拖网作业、天气、站位位置、日期与时间等各类相关信息。