EK60 Water Column Sonar Data Collected During DY1402

Southeastern Aleutian Basin (Bogoslof Island) Acoustic-Trawl Survey of Walleye Pollock (DY1402, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment survey in the Bogoslof Island area of the southeastern Aleutian Basin during late winter of 2014 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). The survey was conducted 7-11 March, departing from Kodiak, Alaska (3 March) and arriving in Dutch Harbor, Alaska (11 March). The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The primary instrument for the survey was a Simrad EK60 split-beam echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz).