Depth-integrated midwater pollock biomass in June, July, and August 2009 (B62)

This data set contains measurements of midwater walleye pollock biomass during annual or biennial acoustic-trawl surveys conducted by the Midwater Assessment and Conservation Engineering (MACE) Program, Resource Assessment and Conservation Engineering (RACE) Division, of the National Oceanic and Atmospheric Administration - National Marine Fisheries Service (NOAA-NMFS) Alaska Fisheries Science Center (AFSC). The survey was conducted from 09 June 2009 through 07 August 2009 using the NOAA Ship Oscar Dyson. Midwater and bottom trawling was used to determine the species and length frequency composition of detected aggregations of fish. Pollock biomass (kg) was computed by applying length-specific target strength values and a length-weight relationship to 38 kHz backscatter data classified as pollock. The summary data set submitted here includes pollock biomass values summed between 16 m below the sea surface and 3 m above the seafloor within a rectangle with a north-south distance of 0.5 nmi (averaging distance along the survey transect) and an east-west distance of 20 nmi (interpolation distance 10 nmi to either side of the survey transect).

本数据集包含由美国国家海洋和大气管理局-国家海洋渔业服务处（NOAA-NMFS）阿拉斯加渔业科学中心（AFSC）资源评估与保护工程（RACE）分部的中层水域评估与保护工程（MACE）计划开展的年度或双年度声学拖网调查期间的中层水域狭鳕生物量实测数据。本次调查于2009年6月9日至2009年8月7日期间实施，所用科考船为NOAA "Oscar Dyson"号。研究人员通过中层拖网与底拖网作业，确定了探测到的鱼群的物种组成与体长频率结构。狭鳕生物量（单位：千克）的计算方式为：将体长特异性目标强度值与体长-体重关系，应用于被分类为狭鳕的38 kHz后散射数据。本次提交的汇总数据集包含指定矩形区域内的狭鳕生物量总和：该矩形以调查样带为中心，南北跨度为0.5海里（沿调查样带的平均间距），东西跨度为20海里（插值间距为样带两侧各10海里），统计范围覆盖海面以下16米至海底以上3米的水层。