Species Identification Confidence in the Bering Sea Slope Surveys (1976-2010)
April 24, 2018
The quality and specificity of field identifications for many taxa have fluctuated over the history of the surveys due to changing priorities and resources. Historical trends in identification quality for each of the major Alaska Fisheries Science Center bottom trawl surveys was documented. These reports include identification confidence matrices for all fish and invertebrates identified from respective surveys.
The Resource Assessment and Conservation Engineering (RACE) Division of the Alaska Fisheries Science Center (AFSC) has been conducting periodic bottom trawl surveys of the upper continental slope of the eastern Bering Sea (EBS) since 1976. Following a pilot survey conducted in 2000 to test the suitability of two versions of the Poly Nor’eastern bottom trawl gear for the slope bottom, a stratified random design following standard trawl protocols has been used to sample trawlable areas of depths from 200 to 1,200 m (Stauffer 2004, Hoff and Britt 2011). In previous years, gears, methods, vessels, and towing stations also were not standardized and therefore those catch data are not comparable with the more recent times series of 2002-2010 (Hoff and Britt 2011). The number of tows conducted also varied substantially over the years, with totals ranging from 50 (in 1976) to over 300 (1982 and 1985) prior to 2002, stabilizing at about 200 with the institution of standardized methodologies in 2002.