2013 Assessment of the Rex Sole Stock in the Gulf of Alaska
April 23, 2013
In 2006, the Gulf of Alaska rex sole (Glyptocephalus zachirus) stock was moved to a biennial stock assessment schedule to coincide with the expected receipt of new survey data. A discussion at the September 2006 Groundfish Plan Team meetings concluded the following two important points for updating information in off-year assessments:
1) Anytime the assessment model is re-run and presented in the SAFE Report, a full assessment document must be produced.
2) The single-species projection model may be re-run using new fishery catch data without rerunning the assessment model.
Thus, on alternate (even) years, parameter values from the previous year’s assessment model and total catch information for the current and previous year are used to make projections via the single species projection model for the following two years and to recommend ABC levels for those years.
Although the GOA Groundfish Survey was successfully conducted this year, results from the survey did not become available to assessment authors until October 1. Because assessment authors were subsequently furloughed from Oct. 1-17 as part of the 2013 federal government shutdown, it was not deemed possible for this stock to complete a full assessment incorporating the new survey data prior to the start of the assessment review process. Instead, the author was instructed to update the assessment by running the single-species projection mode for this stock using the latest fishery catch data without rerunning the assessment model (option 2 above, as if it were an off year for the survey).
Thus, the single species projection model was run using parameter values from the accepted 2011 assessment model, together with updated catch information for 2011-2013, to predict adult biomass for rex sole in 2014 and 2015. The 2011 assessment model is documented in Stockhausen et al. 20111. As per recent assessments for rex sole, predicted adult biomass in 2014 and 2015 was then used to make ABC and OFL recommendations for those years based on Tier 5 calculations.