EK60 Water Column Sonar Data Collected During DY1302

Gulf of Alaska Acoustic-Trawl Survey of Walleye Pollock (DY1302, 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 2013 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). The vessel departed Kodiak, Alaska on 7 February, conducted EK60 echosounder system calibration on 9 February, then returned to Kodiak due to vessel mechanical issues on 12 February. The vessel departed Kodiak on 24 February following repairs, arriving at the start of the first survey on 26 February. The Shumagin Islands survey was conducted 26 February to 1 March and included Shumagin Trough, Stepovak Bay, Renshaw Point, Unga Strait, and West Nagai Strait. The Sanak Trough survey was conducted on 2 March, followed by the Morzhovoi Bay survey on 3 March; the vessel arrived in Kodiak on 4 March. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation.