EK80 Water Column Sonar Data Collected During DY2402

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries (NMFS), Alaska Fisheries Science Center (AFSC), conducted an acoustic-trawl (AT) stock assessment survey in the Southeastern Aleutian Basin near Bogoslof Island 18-25 February 2024, 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 18 February and conducted the survey between 167°and 170° W 23-25 February. A calibration of the EK80 echosounder system was conducted at the start of the previous survey (DY2401) on 4 February in Kalsin Bay, Kodiak Island, Alaska. Trawl operations were conducted using an LFS1421 mid-water trawl net equipped with a Kongsberg FS70 trawl sonar.