2015 - 2018 Marine Biological Association of the United Kingdom (MBA) Western English Channel standard haul demersal fish survey data

Time series data of demersal fish populations in the Western English Channel sampled using a large otter trawl (15m headline) by the Marine Biological Association of the United Kingdom from 2015-2018. This data set contains vertebrate data only from 108 trawls. For each trawl, the entire catch was identified to species level. This dataset contains abundance, length, weight and disk width (if applicable) measurements. This dataset contains consistent sex data for elasmobranchs. Data of lower confidence levels has been excluded including that of invertebrates and sex data of non-elasmobranchs which can be requested via [e-mail]. These excluded data include high confidence cephalopod, scallop and large crab abundance as well as counts of other invertebrates including other crustaceans and echinoderms. Record Types (see SpeciesNotes in taxon form) describe the measurements that were carried out for the sample and/or individuals: Individuals - (Each individual caught has been weighed, measured and counted), Abundance / Weight - (All individuals landed have been weighed and counted as a whole, not individually), Sub-sample (Abundance) - (Measured total weight off all landed individuals, and from this estimated total abundance) & Sub-sample (Weight) - (Counted the total abundance of all landed individuals and from this estimated the total weight). The Sepia team database containing the MBA fisheries data automatically generates unknown weights to read as 1g, this means that it is near impossible to determine whether a weight is unknown or a genuine weight when reads as 1. Therefore any total biomass weights of 1g have been changed to 'unknown'. Individual specimen data has been retained as original vaues since these are more likely to have weights of 1g but should be treated as correct under the data user's discretion.

2015-2018年期间，英国海洋生物协会（Marine Biological Association of the United Kingdom）使用大型拖网（网口宽度15米）在英吉利海峡西部采集的底层鱼类种群时间序列数据。该数据集仅包含来自108次拖网作业的脊椎动物数据。每次拖网的全部渔获物均已鉴定至物种水平。数据集包含丰度、长度、重量及盘宽（如适用）的测量数据。数据集包含软骨鱼类（elasmobranchs）的一致性性别数据。置信度较低的数据已被排除，包括无脊椎动物数据及非软骨鱼类的性别数据，这些排除的数据可通过邮箱[e-mail]申请获取。被排除的数据包含置信度较高的头足类、扇贝及大型蟹类丰度数据，以及其他无脊椎动物（包括甲壳类和棘皮动物）的计数数据。记录类型（详见分类单元表单中的物种注释SpeciesNotes）描述了对样本和/或个体进行的测量类型：个体级（捕获的每个个体均已称重、测量并计数）、丰度/重量（所有上岸个体作为整体称重和计数，而非单独处理）、丰度子样本（测量所有上岸个体的总重量，并据此估算总丰度）及重量子样本（统计所有上岸个体的总丰度，并据此估算总重量）。存储英国海洋生物协会渔业数据的Sepia团队数据库会自动将未知重量生成为1克，这意味着当数值显示为1时，几乎无法判断该重量是未知值还是真实重量。因此，所有1克的总生物量重量均已改为“未知”。个体样本数据保留原始值，因为这些数据更可能存在真实的1克重量，但数据使用者应自行判断其正确性。