EK60 Water Column Sonar Data Collected During DY0809

Echo Integration-Trawl Survey of Walleye Pollock (Theraga chalcogramma) on the U.S. and Russian Bering Sea Shelf (OD2008-09). 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 on the U.S. and Russian Bering Sea shelf during late spring/summer of 2008 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). The survey was conducted from Bristol Bay, eastern Bering Sea in the U.S. to Cape Navarin, Russia, 2 June to 31 August aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The vessel departed Dutch Harbor, Alaska on 2 June and arrived in Dutch Harbor on 31 July. The cruise was completed in three legs (leg 1, 2-19 June; leg 2, 21 June to 10 July; leg 3, 11-31 July), with port calls in Dutch Harbor, Alaska. Experimental and research gear operations were conducted during non-daylight hours and paired trawl net codend comparison experiments and intervessel comparison studies were conducted with NOAA Ship Miller Freeman 20-28 July. The Simrad EK60 scientific echosounder system is the primary acoustic instrument installed on the Dyson and was calibrated at the start of the cruise in Captains Bay, Unalaska Island, Alaska on 2 June, mid-cruise in Captains Bay on 11 July, and at the end of the cruise in Nateekin Bay, Unalaska Island, Alaska on 31 July.