| Assessment of the dusky rockfish stock in the Gulf of Alaska - :17514 | National Marine Fisheries Service (NMFS)
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Assessment of the dusky rockfish stock in the Gulf of Alaska
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    In 2017, the scheduled frequency for some stock assessments was changed in response to the National Stock Assessment Prioritization effort. Prior to 2017, Gulf of Alaska (GOA) rockfish were assessed on a biennial stock assessment schedule to coincide with the availability of new survey data. The new schedule sets full assessments for dusky rockfish in the ‘off’ survey years (even years) and partial assessments for the ‘on’ survey years (odd years). For this year we present a partial assessment consisting of an executive summary including recent fishery catch and survey results, and recommend harvest levels for the next two years. Please refer to the 2015 full stock assessment report for further information regarding the assessment model (Lunsford et al., 2015, available online at http://www.afsc.noaa.gov/REFM/docs/2015/GOAdusky.pdf). A full stock assessment document with updated assessment and projection model results will be presented in next year’s SAFE report. We use a statistical age-structured model as the primary assessment tool for GOA dusky rockfish which qualifies as a Tier 3 stock. The data sets used in the full assessment include total catch biomass, fishery age and size compositions, bottom trawl survey abundance estimates, and bottom trawl survey age compositions. The assessment model consists of a population model, which uses the 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. For a partial assessment year, we do not re-run the assessment model, but do update the projection model with new catch data. This incorporates the most current catch information without re-estimating model parameters and biological reference points.

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