EK60 Water Column Sonar Data Collected During DY1201

Gulf of Alaska Acoustic-Trawl Surveys of Walleye Pollock (DY1201, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the Gulf of Alaska (GOA) during the winter of 2012 to estimate the distribution and abundance of walleye pollock (Theraga chalcogramma). The vessel departed Kodiak, Alaska on 13 February, conducted EK60 echosounder system calibration on 14 February, then proceeded to the start of the first survey (Sanak Trough, 15 February). The vessel then proceeded to the Shumagin Islands and conducted surveys at Shumagin Trough, Stepovak Bay, Renshaw Point, Unga Strait, and West Nagai Strait, 16-19 February. The vessel conducted multibeam echosounder surveys of select locations and deployed ARGO drifters 19-22 February and returned to Kodiak on 22 February. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation.