AFSC/ABL: Frederick Sound Echo-integrated Trawl Survey, 2001 to 2004

The acoustic trawl database for Frederick Sounds echo-trawl survey was conducted from 2001 to 2004. The surveys were conducted throughout most of the southern part of Stephens Passage and Frederick Sound in southeast Alaska and all their adjoining bays. Acoustic and trawl surveys were conducted every 3 months to verify acoustic signals and to collect biological data. This study was conducted to study the relationship between Steller sea lions (Eumetopias jubatus) and their prey. Acoustic equipment were calibrated before every trawl survey. Trawls were used to identify the fish species associated with a specific acoustic signal and to get length weight data per species. Acoustic data were analyzed by the same qualified acoustician throughout the surveys duration with calibrations entered into the analytical software after each calibration.
Trawl data were used to enumerate and identify all nekton found within the study area and to generate length frequencies, species composition and abundance by season. The acoustic data was use to generate biomass estimates for Pacific herring, Pacific hake and walleye pollock. Longlines were deployed to better identify and enumerate the benthic species not usually caught in pelagic trawls.