EK80 Water Column Sonar Data Collected During DY2303

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC), conducted an acoustic-trawl (AT) stock assessment survey in the Shumagin Islands, Pavlof Bay, Morzhovoi Bay, and Sanak areas of the Gulf of Alaska (GOA) 10-22 February 2023, to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). The survey was conducted aboard NOAA Ship Oscar Dyson (built in 2003, 64 meters, 2500 tons, 3100 hp), a research stern trawler equipped with acoustic and oceanographic instrumentation. The primary water column acoustic instrument for the survey was a Kongsberg EK80 split-beam scientific echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 10 February and conducted the survey 14-20 February. A calibration of the EK80 echosounder system was conducted prior to starting the survey on 12 February Uyak Bay, Kodiak Island, Alaska. Trawl operations were conducted using an LFS1421 mid-water trawl net.