2018 Assessment of the Walleye Pollock Stock in the Gulf of Alaska
The base model projection of female spawning biomass in 2019 is 345,352 t, which is 62.4% of unfished spawning biomass (based on average post-1977 recruitment) and above B40% (221,000 t), thereby placing GOA pollock in sub-tier “a” of Tier 3. New survey data in 2018 are highly contrasting, with the 2018 Shelikof Strait acoustic survey indicating high biomass, and the ADFG trawl survey indicating relatively low biomass (though increased from the previous two years). The risk matrix table recommended by the
SSC was used to determine whether to recommend an ABC lower than the maximum permissible. The table is applied by evaluating the severity of three types of considerations that could be used to support a scientific recommendation to reduce the ABC from the maximum permissible. We identified substantially increased concerns for the stock assessment, the population dynamics of pollock, and environmental/ecosystem factors that are likely to affect pollock.
Assessment considerations: In the last several years, there have been strongly contrasting trends in the survey abundance indices, with bottom trawl indices showing a steep decline, while acoustic surveys showing record highs. The model is unable to fit strongly contrasting trends, which has resulted in very poor model fits to the most recent survey indices. This increases the uncertainty of the assessment.