EK80 Water Column Sonar Data Collected During DY2001

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the Gulf of Alaska (GOA) during the winter of 2020 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). These surveys were conducted aboard NOAA Ship Oscar Dyson, a 64 meter research stern trawler equipped with acoustic and oceanographic instrumentation. The primary acoustic instrument for the surveys was a Simrad EK80 split-beam echosounder system utilizing six frequencies (18, 38, 70, 120, 200, and 333 kHz). The vessel departed Kodiak, Alaska on 11 February and conducted the Shumagin Islands survey (including Shumagin Trough, Stepovak Bay, Renshaw Point, Unga Strait, and West Nagai Strait) and ended the cruise in Sand Point, Alaska on 17 February, 2020. A calibration of the EK80 echosounder system was conducted at the start of the cruise on 12 February in Uganik Bay, Kodiak Island, Alaska.