CE12005 Blue Whiting Acoustic Survey

An acoustic survey targeting blue whiting (Micromesistius poutassou) spawning and post spacing aggregations in the north east Atlantic from 22nd March to 11st April 2012. 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 2012 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 to the western flanks of the Rockall Bank. The survey was part of an international collaborative survey using the vessels RV Celtic Explorer (Ireland), RV Fridtjof Nansen (Russia), RV Tridens (Netherlands) and the RV Magnus Heinason (Faroes) and the FV Brennholm (Norway). 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 mid-water trawl. All components of the catch from the trawl hauls were sorted and weighed; fish and other taxa were identified to species level. 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 data2012年3月22日至4月11日，在东北大西洋开展了针对蓝鳕（Micromesistius poutassou）产卵及产卵后集群的声学调查。产卵活动于每年1月至4月间在大陆架边缘开展，分布范围从南波尔丘派恩浅滩区域向北延伸至法罗-设得兰海岭，涵盖罗斯玛丽海丘、哈顿海丘与罗科尔海丘等近海海域。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即安排在此阶段内。 为采用更协调的时空统一调查方案，参与国每年都会在国际海洋考察理事会（ICES, International Council for the Exploration of the Sea）牵头的国际中上层鱼类调查工作组（WGIPS, Working Group on International Pelagic Surveys）会议上商讨调查方法并明确作业分配方案。 2012年本次调查覆盖了苏格兰以西与西部群岛周边的蓝鳕核心产卵区，作业范围从大陆架斜坡（水深250米处）向西延伸至罗科尔海丘西侧坡地。本次调查属于国际协作项目，参与作业的船只包括：爱尔兰的"凯尔特探险家号"（RV Celtic Explorer）科研调查船、俄罗斯的"弗里乔夫·南森号"（RV Fridtjof Nansen）科研调查船、荷兰的"特里登斯号"（RV Tridens）科研调查船、法罗群岛的"马格努斯·海纳森号"（RV Magnus Heinason）科研调查船，以及挪威的"布伦霍姆号"（FV Brennholm）捕捞渔船。各船只的作业方案与任务分配均已提前达成一致。 调查采用平行断面设计，以便在联合调查的东西走向目标区域实现断面交错布设。声学数据通过Simrad ER60科学回声仪采集。作业过程中尽可能将航速维持在最高10节（KTS, Knots）。 生物样本采集采用单网次中上层拖网：对拖网获取的渔获物所有组分进行分类分拣与称重，将鱼类及其他类群鉴定至物种水平。在预设站位采集温度、水深与盐度等温盐深（CTD, Conductivity Temperature Depth）数据。 本次调查的核心目标为： 1. 采集蓝鳕产卵集群的声学数据； 2. 通过针对鱼类声学回波痕迹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. 采集温盐深（CTD）数据。