Pelagic Fish at the Barents Sea Polar Front in August 2023

## Methods ### Study area This dataset is the result of sampling at nine stations at the Polar Front, in the western part of the Barents Sea. Some stations were sampled twice at different depths. ### Time coverage The samples were collected between 16 August 2023 and 25 August 2023. ### Sampling 15 pelagic trawl samples were collected with a Harstad pelagic trawl, which has an effective opening of 80 m2 when towed at ca. 3 knots. The mesh size of the inner liner of the cod end was 10 mm. The pelagic trawl was towed at ca. 3 knots for 20-30 min at the target depth and abundances were standardized by converting to catch per unit effort (expressed in kilograms per cubic meter). ### Sample analysis All organisms were identified, when possible to to species level, otherwise to the lowest taxonomic rank possible by visual identification onboard. Capelin had a large size distribution, so individuals similar in length were sorted into approximate size classes (small, medium, and large). The total number and weight of each species was recorded. For large catches, subsamples of 20-30 individuals were taken as a representation of the length distributions of the catch. The standard length, height at the anus (up to the nearest 1 mm), and weight (up to the nearest 0.1 g) were measured for all specimens caught and those in the subsample for abundant species. ### Data managementWhile the PolarFront project publishes all its data on Zenodo, biological diversity datasets are also published in the Global Biodiversity Information Facility (GBIF).The data is prepared using the international Darwin Core (DwC) vocabulary (https://dwc.tdwg.org/) and is distributed as DwC text files that follows GBIF's [data quality requirements](https://www.gbif.org/data-quality-requirements-sampling-events) and [best practices for sampling event datasets](https://ipt.gbif.org/manual/en/ipt/latest/best-practices-sampling-event-data). Prior to publishing all data files are validated using GBIF's data validator (https://www.gbif.org/tools/data-validator). Taxonomy is also validated against the [GBIF API](https://techdocs.gbif.org/en/openapi/v1/species) and [World Register of Marine Species](https://www.marinespecies.org).## 方法 ### 研究区域 本数据集为巴伦支海（Barents Sea）西部极锋（Polar Front）区域9个站位的采样成果，其中部分站位在不同深度开展了两次采样。 ### 时间覆盖范围 样本采集时间为2023年8月16日至2023年8月25日。 ### 采样方案 共使用哈斯塔德远洋拖网（Harstad pelagic trawl）采集15个远洋拖网样本，该拖网在约3节航速下拖曳时有效开口面积为80平方米。其囊网内衬网目尺寸为10毫米。该远洋拖网在目标深度以约3节航速拖曳20至30分钟，捕捞数据通过转换为单位捕捞努力量渔获量（以千克每立方米表示）进行标准化处理。 ### 样本分析 所有采集到的生物均尽可能鉴定至物种水平，若无法实现则通过船上目视鉴定至最低可行分类阶元。 毛鳞鱼（Capelin）的体长分布跨度较大，因此将体长相近的个体划分为近似尺寸等级（小型、中型及大型）。 记录各物种的总个体数与总重量。 针对捕捞量较大的样本，选取20至30个个体作为子样本，以代表该批次捕捞样本的体长分布。对于所有捕获标本及丰度较高物种的子样本，均测量其标准体长、肛门处体高（精确至1毫米）及体重（精确至0.1克）。 ### 数据管理 尽管极锋项目（PolarFront project）将所有数据发布于Zenodo平台，但生物多样性数据集同时也上传至全球生物多样性信息设施（Global Biodiversity Information Facility, GBIF）。 本数据集采用国际达尔文核心（Darwin Core, DwC）词汇表（https://dwc.tdwg.org/）进行规范整理，以遵循GBIF的[采样事件数据质量要求](https://www.gbif.org/data-quality-requirements-sampling-events)及[采样事件数据集最佳实践规范](https://ipt.gbif.org/manual/en/ipt/latest/best-practices-sampling-event-data)的DwC文本文件形式进行分发。 所有数据文件在发布前均通过GBIF数据验证工具（https://www.gbif.org/tools/data-validator）进行校验。分类学信息同时通过GBIF API（https://techdocs.gbif.org/en/openapi/v1/species）及世界海洋物种登记册（World Register of Marine Species, WoRMS）进行验证。