ME70 Water Column Sonar Data Collected During DY1201

Shumagin Islands Acoustic-Trawl Survey of Walleye Pollock (DY1201, ME70). The Midwater Assessment and Conservation Engineering (MACE) program of the Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment survey in the Gulf of Alaska (GOA) during the late winter of 2012 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). The survey areas included the Shumagin Islands (February 15-16, 2012) and Sanak Trough (February 17-20, 2012). The survey was conducted onboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation in addition to trawling and biological sampling capabilities. The primary instrumentation for the survey was a Simrad EK60 split-beam echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz) and a Simrad ME70 multibeam echosounder, with the ME70 trigger slaved to the EK60 system.