AFSC/RACE/MACE: Pollock Acoustic/Trawl Survey Spawning Biennial Bogoslof

Scientists from the Alaska Fisheries Science Center conduct biennial acoustic-trawl surveys of pre-spawning walleye pollock (Gadus chalcogrammus) during late February and early March in the southeastern Aleutian Basin near Bogoslof Island, Alaska. These surveys were conducted annually between 1988 and 2007 (with the exception of 1990 and 2004), and biennially starting in 2009 (with the exception of 2011). In recent years, survey coverage extends from Unalaska Island to the Islands of Four Mountains, over bottom depths of approximately 50 m to 1000 m. The biomass estimate for pollock within the Central Bering Sea Convention Specific Area obtained during this acoustic-trawl survey provides an index of abundance for the Aleutian Basin stock, and provides pollock abundance and spatial distribution information by length and age for the Central Bering Sea, Bogoslof management area. Midwater catches associated with the acoustic backscatter are identified and enumerated to species or species groups. Ocean temperatures are collected throughout the survey region.

The pre-spawning pollock population estimates from this acoustic-trawl survey are the primary data source for the Central Bering Sea, Bogoslof Island area stock assessment model. Results from this model guides the North Pacific Fisheries Management Council’s decisions on U.S. pollock stock management and provides an index of abundance for the Aleutian Basin stock.