2018 Assessment of the Alaska Plaice Stock in the Bering Sea and Aleutian Islands
January 29, 2019
Alaska plaice (Pleuronectes quadrituberculatus) are assessed on a biennial stock assessment schedule as part of the National Marine Fisheries Service assessment prioritization plan implemented in 2017. For Bering Sea/Aleutian Islands partial assessments, an executive summary is presented to recommend harvest levels for the next two years. Please refer to last year’s full stock assessment report for further information regarding the stock assessment model. A full stock assessment document with updated assessment and projection model results is scheduled to be presented in next year’s (2019) SAFE report.
A statistical age-structured model is used as the primary assessment tool for the Bering Sea/Aleutian Islands Alaska plaice assessment, a Tier 3 stock. This assessment consists of a population model that uses survey and fishery data to generate a historical time series of population estimates, and a projection model, which uses results from the population model to predict future population estimates and recommended harvest levels. The data sets used in this assessment include total catch biomass, fishery age compositions, trawl survey abundance estimates and trawl survey age compositions. In a partial assessment year, the full assessment model is not rerun but instead a Tier 3 projection model with an assumed future catch is run to estimate the stock level in future years. This incorporates the most current catch information without re-estimating model parameters and biological reference points. The Tier 3 projection operates outside the full assessment model by projecting estimates of future female spawning biomass, age 6+ total biomass, ABC and OFL from the full model estimate of 2017 numbers-at-age and weight-at-age.