Survey : GEBL/K/1939 (part of CEFAS Historic surveys)

This survey was undertaken by Cefas as part of the CEFAS Historic surveys; Station and biological data collected during research surveys carried out by Cefas (formerly Directorate of Fisheries) in seas around the UK, mostly in the North Sea, since 1902. The survey hauls are not laid out systematically as a grid, as in current International Bottom Trawl Surveys (IBTS) and are widely distributed over (especially) southern and central North Sea areas. Gears and protocols were not standardised throughout, due to the long term nature of the series. Surveys took place in each season. Data are lacking for the periods of both World Wars. In some periods (e.g. the early 1900s), all species caught were recorded, whereas in other periods (e.g. 1920s-30s), only the key commercial species (e.g., Plaice, Sole and Cod) were recorded systematically. Note that some surveys targeted particular species (notably Plaice). Survey took place between 04/07/1939 and 12/07/1939 on GBligh Equipment used during this survey : - Otter trawl Codend catch Survey operations were undertaken on 9 stations 5 different species were caught on this survey本数据集对应的调研由环境、渔业与水产养殖科学中心（Centre for Environment, Fisheries and Aquaculture Science, Cefas）作为Cefas历史调研项目的组成部分实施；数据集包含自1902年起，Cefas（前身为渔业总署）在英国周边海域（主要为北海）开展科研调研所采集的站位与生物数据。调研拖网作业点未像现行国际底拖网调研（International Bottom Trawl Surveys, IBTS）那样以网格形式系统布设，而是广泛分布于（尤其是）北海南部与中部海域。由于该调研序列具有长期延续性，全程未统一作业渔具与操作规范，且各季均开展过调研。两次世界大战期间的数据存在缺失。部分调研时段（如20世纪初）会记录所有捕获物种，而另一些时段（如20世纪20至30年代）仅系统记录主要经济物种（如欧鲽、鳎鱼与鳕鱼）。需注意，部分调研以特定物种为目标（尤以欧鲽为甚）。 1939年7月4日至1939年7月12日，本次特定调研在GBligh号科考船上开展。 本次调研使用的设备： - 翼网拖网囊网渔获（Otter trawl Codend catch） 本次调研共完成9个站位的作业。 本次调研共捕获5个不同物种。