| The Midwater Assessment and Conservation Engineering (MACE) program of NOAA?s National
Marine Fisheries Service, Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl
(AT) stock assessment survey in the Gulf of Alaska (GOA) during late winter and early
spring of 2013 to estimate the distribution and abundance of walleye pollock (Gadus
chalcogrammus). The survey areas included the Shelikof Strait, Marmot Bay, and along
the GOA shelf break east of Chirikof Island (March 15-27, 2013). The survey was conducted
aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and
oceanographic instrumentation, 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 synchronized to the EK60 system. |