Description
Alaska pollock (Gadus chalcogrammus), a semi-demersal gadoid fish species that inhabit the continental shelves of the North Pacific Ocean and Bering Sea, support one of the largest single species fisheries in the world. Sustainable management of this stock is based on fishing industry catch and effort information as well as fishery-independent information from acoustic and trawl surveys. The biennial acoustic-trawl survey is conducted between June and August by NOAA fisheries scientists aboard a U.S. government research vessel (currently NOAA ship Oscar Dyson) to monitor pollock on the eastern Bering Sea shelf and slope. Results from this acoustic-trawl survey provide midwater pollock abundance and spatial distribution information by length and age from Bristol Bay in the United States, to Cape Navarin, Russia, over bottom depths of approximately 50 m to 1000 m. Temperature, salinity and other water column properties are measured. Midwater and bottom trawl catches associated with the acoustic backscatter are enumerated by species or species group. Preliminary spatial distributions of euphausiid backscatter are also estimated.
Purpose
The midwater pollock population estimates from the acoustic-trawl survey is one of three key inputs for the pollock stock assessment model, which in turn guides the North Pacific Fisheries Management Council’s annual decisions on U.S. Bering Sea pollock stock management. (Additional key inputs are demersal pollock population estimates from an annual NOAA Bering Sea bottom trawl survey, and biological data from the pollock fishing industry.)
