DFO Pacific Outside North Hard Bottom Longline Surveys

The Outside North Hard Bottom Longline (HBLL) survey is one of a set of long-term and coordinated surveys that together cover most of the nearshore, hard-bottom habitat of coastal British Columbia. The other surveys are the Outside South HBLL survey, Inside North HBLL survey, and Inside South HBLL survey. The Outside North HBLL survey was first conducted in 2006 and has been repeated every second year in alternate years to the Outside South HBLL survey, with the exception that no surveys were conducted in 2013. The survey was not impacted by the COVID-19 pandemic. The objective of these surveys is to provide fishery-independent abundance indices and associated biological data for the assessment of nearshore rockfishes and other groundfish species that live on untrawlable, hard bottom habitats. The surveys follow a random depth-stratified design and the sampling units are 2 km by 2 km blocks. The Outside HBLL surveys use size 14/0 circle hooks, baited with frozen squid. The Outside North HBLL Survey is conducted by DFO in collaboration with the Pacific Halibut Management Association (PHMA) and takes place on several chartered commercial fishing vessels each year. This survey covers the northern portion of the British Columbia coastline, including the mainland coast north of Milbanke Sound, Dixon Entrance, and the east and west coasts of Haida Gwaii. The PHMA provides the chartered commercial fishing vessels and field technicians, while DFO provides support for running the surveys, including survey design and equipment. The data provided include information about the annual survey trips and fishing events (tows/sets) that are part of this survey series, including the vessel name, dates, times, spatial coverage, gear details, and effort information. Catch information (total weight in kg or counts of individual specimens) is included from successful fishing events. Catches are identified to species or to the lowest taxonomic level possible. Most catches are weighed, but some are too small (“trace” amounts) or too large (e.g. very large Big Skate). Some catches were subsampled and biological data were collected from individual fish specimens, including length, sex, and weight information. Where age structures were collected and processed, fish ages have been included.外北硬质底延绳钓（Hard Bottom Longline, HBLL）调查是一组长期协同调查的组成部分，该组调查共同覆盖了不列颠哥伦比亚省沿海近岸硬质底栖息环境的绝大部分区域。其余三项调查分别为外南硬质底延绳钓（HBLL）调查、内北硬质底延绳钓（HBLL）调查与内南硬质底延绳钓（HBLL）调查。 外北硬质底延绳钓（HBLL）调查于2006年首次开展，此后每两年开展一次，与外南硬质底延绳钓（HBLL）调查交替进行，但2013年未实施任何调查。本次调查未受COVID-19疫情影响。此类调查的核心目标是提供独立于渔业的丰度指数及配套生物学数据，用于评估栖息于非拖网作业硬质底栖息环境的近岸岩礁鱼类及其他底层鱼类物种。调查采用随机深度分层设计，采样单元为2km×2km的地理区块。外北硬质底延绳钓（HBLL）调查使用14/0号圆形钓钩，饵料为冷冻鱿鱼。 外北硬质底延绳钓（HBLL）调查由加拿大渔业与海洋部（Department of Fisheries and Oceans, DFO）与太平洋大比目鱼管理协会（Pacific Halibut Management Association, PHMA）合作实施，每年依托多艘租赁商业渔船开展。本次调查覆盖不列颠哥伦比亚省沿海北部区域，包括米尔班克湾以北的大陆沿岸、迪克森海峡以及海达瓜依群岛的东西两岸。PHMA负责提供租赁的商业渔船及野外技术人员，DFO则为调查运行提供全流程支持，包括调查设计与设备保障。 本次提供的数据涵盖本调查系列中的年度调查航次与捕捞作业（拖曳/放钩）信息，具体包括渔船名称、作业日期与时间、空间覆盖范围、渔具细节及捕捞努力量信息。成功捕捞作业的渔获信息（以千克计的总重量或个体标本计数）已纳入数据集。渔获均鉴定至物种级别或尽可能低的分类学层级。多数渔获均进行称重，但部分渔获因体量过小（“痕量”样本）或过大（例如体型极大的大鳐）未实施称重。部分渔获被进行子采样，并从个体鱼类标本中采集了生物学数据，包括体长、性别与体重信息。若已采集并处理了年龄结构数据，则一并纳入鱼类年龄信息。