2014 Assessment of the Rougheye and Blackspotted Rockfish Stock Complex in the Gulf of Alaska
Rockfish are assessed on a biennial stock assessment schedule to coincide with the availability of new survey data. For Gulf of Alaska (GOA) rockfish in off-cycle (even) years, we typically present an executive summary to recommend harvest levels for the next two years. However, last year during an oncycle (odd) year, we presented an executive summary similar to an off-cycle year for GOA rougheye and blackspotted (RE/BS) rockfish due to the 2013 government shutdown and extensive data updates that were needed. The GOA Plan Team (November 2013) subsequently recommended a full stock assessment be presented in 2014. We, therefore, present a full stock assessment document with updated assessment and projection model results to recommend harvest levels for the next two years.
We use a statistical age-structured model as the primary assessment tool for Gulf of Alaska rougheye and blackspotted rockfish (RE/BS complex) which qualifies as a Tier 3 stock. This assessment consists of a population model, which 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 and size compositions, trawl and longline survey abundance estimates, trawl survey age compositions, and longline survey size compositions. For this assessment year, there are three models presented in the assessment. Model 0 is the last full assessment base model from 2011. Model 1 is an intermediate model which uses all the new and updated data but keeps the previous longline survey abundance index based on weights and the old conversion matrices. Finally, Model 2 is the author preferred model which uses all the new and updated data, the longline survey abundance index based on numbers, and the updated conversion matrices.