CE17004 Blue Whiting Acoustic Survey

An acoustic survey targeting blue whiting (Micromesistius poutassou) spawning and post spawning aggregations in the north east Atlantic in 2017. Flashing takes place from January through to April along the shelf edge from the southern Porcupine Bank area northwards to the Faroe/Shetland Ridge including offshore areas as the Rosemary, Hatton and Rockall Banks. Peak spawning occurs between mid-March and mid April and acoustic surveys are timed to occur during this phase. To facilitate a more coordinated spatio-temporal approach to the survey participating countries meet annually to discuss survey methods and define effort allocation at the ICES led Working Group International pelagic Surveys (WGIPS). The survey covered the core spawning area of blue whiting to the west of Scotland and the Western Isles. Coverage extended from the shelf slopes (250 m) Westward into the Rockall Trough. The survey was carried out in continuity from north to south and from south to north The survey was part of an international collaborative survey using the RV Celtic Explorer (Ireland), RV Tridens (Netherlands), FV Kings Bay (Norway) and the RV Magnus Heinason (Faroes). Transparent design and effort allocation was pre-agreed for each vessel. A parallel transect design was used to allow transect interlacing in co-surveyed target areas (east-west orientation). Acoustic data were collected using the Simrad ER60 scientific echosounder. Cruising speed was maintained at a maximum of 10 KTS (Knots) where possible. Biological sampling was done using a single pelagic midwater trawl.All components of the catch from the trawl hauls were sorted and weighed; fish and other taxa were identified to species level. One marine mammal observer (MMO) was present on board to record visual observations of marine mammals. Passionive Acoustic Monitoring (PAM) for cetaceans were also conducted using a towed hydrophone array which was deployed on a 200 m cable and towed behind the vessel. Seabird surveys were also carried out. Oceanographic data on temperature, depth and salinity (CTD) were collected at set stations. 1. Collect acoustic data on blue whiting spawning aggregations 2. Collective biological samples from Directed Trawling on fish echotraces to determine age structure and Maturity state of survey stock 3. Collect CTD data 4. Conduct visual Abundance surveys of marine mammals and seabirds in conjunction with Passive acoustic monitoring of marine mammals本数据集为2017年在东北大西洋开展的、针对蓝鳕（*Micromesistius poutassou*）产卵及产卵后聚集鱼群的声学调查。本次调查作业于1月至4月间展开，航线沿陆架边缘从南豪猪滩（Porcupine Bank）海域向北延伸至法罗-设得兰海岭（Faroe/Shetland Ridge），覆盖罗斯玛丽滩（Rosemary Bank）、哈顿滩（Hatton Bank）与罗科尔滩（Rockall Bank）等近海外围区域。蓝鳕的产卵盛期为3月中旬至4月中旬，本次声学调查的时间安排即覆盖该关键时段。为采用更协同的时空调查方案，参与调查的成员国每年都会在国际海洋考察理事会（ICES）牵头的国际中上层鱼类调查工作组（WGIPS, Working Group International pelagic Surveys）上讨论调查方法并明确作业分配方案。本次调查覆盖了苏格兰以西及西部群岛周边的蓝鳕核心产卵场，作业范围从陆架斜坡（水深250米处）向西延伸至罗科尔海槽（Rockall Trough）。调查采用南北往返的连续航行模式开展。本次调查属于国际协作项目，使用的科考船包括爱尔兰的“凯尔特探索者号”（RV Celtic Explorer）、荷兰的“特里登斯号”（RV Tridens）、挪威的“国王湾号”（FV Kings Bay）以及法罗群岛的“马格努斯·海纳森号”（RV Magnus Heinason）。各船只的透明化调查设计与作业配额均已提前商定。本次调查采用平行断面设计，以便在共同调查的目标区域内实现东西向断面的交错布设。声学数据通过Simrad ER60科学回声测深仪采集，作业过程中尽可能将航速维持在最高10节（Knots, KTS）。本次调查采用单一中上层中层拖网开展生物采样：拖网捕获的所有渔获组分均经过分拣与称重，鱼类及其他类群均鉴定至物种水平。船上配备1名海洋哺乳动物观察员（Marine Mammal Observer, MMO），负责记录海洋哺乳动物的目视观测结果；同时通过拖曳式水听器阵列开展鲸类被动声学监测（Passive Acoustic Monitoring, PAM），该阵列通过200米缆绳拖于船尾。本次调查同步开展海鸟调查，并在预设站位采集温度、深度与盐度的海洋学数据（CTD, Conductivity Temperature Depth）。本次调查的核心目标包括：1. 采集蓝鳕产卵鱼群的声学数据；2. 通过针对鱼类声学回声层的定向拖网采集生物样本，以确定调查种群的年龄结构与成熟状态；3. 采集CTD海洋物理数据；4. 开展海洋哺乳动物与海鸟的目视数量调查，同时配套开展海洋哺乳动物被动声学监测。