Echo Integration-Trawl Survey Results for Walleye Pollock (Theragra chalcogramma) on the Bering Sea Shelf and Slope during Summer 1999 and 2000

摘要

This report contains methodology, results and some discussion of two summer echo integration-trawl (EIT) surveys of walleye pollock (Thereagra chalcogramma) on the eastern Bering Sea shelf and slope conducted in 1999 and 2000. This research was carried out by the Midwater Assessment and Conservation Engineering (MACE) Program at the Alaska Fisheries Science Center, Seattle, Washington, as part of the historical time series monitoring the midwater component of Bering Sea walleye pollock. While EIT surveys are completed in conjunction with the AFSC's Groundfish Assessment Program's annual bottom trawl surveys to separately assess the on-bottom component of Bering Sea pollock, bottom trawl results are not presented here. Although EIT survey design and timing were nearly the same between 1999 and 2000, each year's work had a slightly different scope and research team, thus the results are presented sequentially as two separate papers. To the extent possible, subheadings and sections used are the same for each year, but in some cases they differ.