Pelagic biomasses in the northern and southern Barents Sea for the period 1993-2013

Estimated pelagic biomasses (million tonnes wet weight) of pelagic fish stocks (capelin, herring, blue whiting, and polar cod) and 0-group fishes (cod, herring, haddock, polar cod, redfish, Greenland halibut, long rough dab, wolffish, blue whiting, and saithe) and macroplankton (mainly krill) in the northern and southern Barents Sea for the period 1993-2013. The background data were taken from [1]). Data for biomass calculation were collected during surveys: Trawl data for pelagic fish, 0-group fish, macroplankton were collected during a joint Norwegian-Russian 0-group fish trawl survey in August-September 1993-2003 using a small-meshed pelagic trawl (“Harstad”) with 20m*20m mouth opening [2]. Acoustic data for pelagic stocks (capelin, herring, blue whiting, and polar cod) were collected in September-October 1993-2003. Acoustic data are integrated continuously along the survey tracks, and mean values of acoustic back-scattering per nautical mile (nm) are recorded for mapping and calculations of fish biomass. The echo sounders are monitored continuously, and trawl hauls (“Harstad” trawl) are carried out whenever the recordings change their characteristics and/or the need for biological data makes it necessary [3]. Since 2004, both the 0-group trawl survey and the acoustic capelin survey have been part of a Barents Sea ecosystem survey (BESS, [4, 5]). The timing of the BESS allows access by research vessels to most of or the whole Barents Sea, sea-ice being at its seasonal minimum. In August-September, migratory species such as capelin have reached their maximum northern distribution at the end of the summer feeding period. At this time of year, the juvenile 0-group fish of commercially and ecologically important species are sufficiently large to be caught by trawl, while 0-group demersal species such as cod and haddock have not yet settled to the bottom. For further description of the sample processing, determination of biomass, and data series see [1].

本数据集涵盖1993-2013年巴伦支海北部与南部海域中上层鱼类种群（毛鳞鱼、鲱鱼、蓝鳕、北极鳕）、0龄鱼类（0-group fishes，包括鳕鱼、鲱鱼、黑线鳕、北极鳕、大西洋红鱼、格陵兰庸鲽、长粗黄盖鲽、狼鳗、蓝鳕、青鳕）以及大型浮游动物（主要为磷虾）的估算中上层生物量，单位为百万吨湿重。本数据集的基础数据源自文献[1]。用于生物量计算的数据采集自多项调查：1993-2003年8-9月，挪威-俄罗斯联合开展的0龄鱼类拖网调查中，研究人员采用网口尺寸为20m×20m的小型中上层拖网"Harstad"，采集了中上层鱼类、0龄鱼类与大型浮游动物的拖网数据[2]。1993-2003年9-10月，研究人员针对中上层鱼类种群（毛鳞鱼、鲱鱼、蓝鳕、北极鳕）采集了声学调查数据。声学数据沿调查航线连续积分，每海里（nautical mile, nm）的平均声学后向散射值被记录，用于鱼类生物量的绘图与计算。回声测深仪始终处于持续监测状态，当声学记录特征发生变化，或因生物数据采集需求时，即开展"Harstad"拖网采样作业[3]。自2004年起，0龄鱼类拖网调查与毛鳞鱼声学调查均纳入巴伦支海生态系统调查（Barents Sea Ecosystem Survey, BESS，文献[4,5]）。该调查的作业时段可保障科研调查船抵达巴伦支海大部分乃至全部海域，此时海冰处于季节最小值。每年8-9月，毛鳞鱼等洄游性鱼类在夏季索饵期结束后，已抵达其最北分布范围；此时兼具经济与生态重要性的物种的0龄幼体体型已足够大，可通过拖网捕获，而鳕鱼、黑线鳕等0龄底栖鱼类尚未沉降至海底。关于样本处理、生物量测定与数据序列的详细说明，请参见文献[1]。