BSAI Chapter 5

The assessment of Bering Sea and Aleutian Islands (BSAI) Greenland turbot has been moved to a biennial schedule according to the stock assessment prioritization schedule. A partial assessment was done for BSAI Greenland turbot this year. In partial assessment years, an executive summary is presented with recommendations of harvest levels for the next two years. The 2016 full assessment is available online at https://www.afsc.noaa.gov/REFM/Docs/2016/BSAIturbot.pdf. The next full assessment will be conducted in 2018. Updated assessment and projection model results will be presented in next year’s SAFE report. A statistical age-structured model was configured in Stock Synthesis 3 (Methot and Wetzel, 2013) and was used as the primary stock assessment tool for BSAI Greenland turbot, which qualifies as a Tier 3 stock. This assessment consists of a population model to generate historical time series of population estimates and a projection model to predict future population estimates and recommended harvest levels. The data sets used in this assessment included fishery catch data (trawl and longline), survey biomasses from the Eastern Bering Sea shelf and slope surveys and the Auke Bay Laboratory’s longline survey, length composition data from the trawl and longline fisheries and the shelf and slope surveys, and meansize-at-age data from the shelf survey. For a partial assessment year, we do not re-run the assessment model, but update the projection model with the new catch data. This report incorporates the most current catch information without re-estimating model parameters and biological reference points.

Stock Assessment