Heard Island and McDonald Islands Random Stratified Trawl Survey (RSTS) strata

A trawl survey is conducted each year at Heard Island and McDonald Islands (HIMI) to assess the abundance and biology of fish and invertebrate species. The survey provides information for input into the stock assessments for the two main fished species, Patagonian toothfish (Dissostichus eleginoides), and mackerel icefish (Champsocephalus gunnari). In addition, it provides information on biodiversity and bycatch species from the fishery. Nine strata were defined as areas for sampling during the annual Random Stratified Trawl Survey (RSTS) conducted on board an industry vessel. The area of the plateau down to 1000 metres depth was divided into nine strata, each covering an area of similar depth and/or fish abundance. A number of randomly allocated stations (between 10 and 30) are sampled in each stratum during every survey to assess the abundance of juvenile and adult toothfish on the shallow and deep parts of the Heard Island Plateau (300 to 1000 metres depth) and to assess the abundance of mackerel icefish on the Heard Island Plateau. Although the number and boundaries of strata have been adjusted over the years, they have been consistent since 2002 (Welsford et al. 2006).This dataset consists of a polygon shapefile representing the strata and a map displaying the strata.

赫德岛和麦克唐纳群岛（Heard Island and McDonald Islands，缩写HIMI）每年都会开展拖网调查，以评估鱼类与无脊椎动物物种的丰度及生物学特征。本次调查所获信息可用于两种主要捕捞物种的资源评估：巴塔哥尼亚齿鱼（Patagonian toothfish，学名Dissostichus eleginoides）与鲭冰鱼（mackerel icefish，学名Champsocephalus gunnari）。此外，该调查还可提供该渔场的生物多样性及兼捕物种相关数据。在行业作业船舶上开展的年度随机分层拖网调查（Random Stratified Trawl Survey，缩写RSTS）中，共划定9个分层作为采样区域。调查覆盖水深不超过1000米的海台范围，该区域被划分为9个分层，每个分层的水深区间与/或鱼类丰度均较为相近。每次调查期间，每个分层内会布设10至30个随机分配的采样站位，用于评估赫德岛海台（水深300至1000米）浅水区与深水区的幼龄及成体齿鱼丰度，同时评估赫德岛海台的鲭冰鱼丰度。尽管历年的分层数量与边界均有调整，但自2002年起其设置已保持稳定（Welsford等，2006）。本数据集包含表征分层的多边形形状文件（polygon shapefile）以及分层分布图。