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Status of Stocks & Multispecies Assessment Program

Update on Groundfish Stock Assessments for the 2013 Fishery (cont.)

Research Reports
Oct-Nov-Dec 2012
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Gulf of Alaska (GOA)

In the GOA, the main species trends were mixed.  The ABC for pollock increased by 4% relative to 2012; whereas, the Pacific cod and sablefish ABCs declined by 8% and 3%, respectively.  The sum of the recommended ABCs for 2013 is 595,920 t which represents a 2% decrease from the 2012 total.  New fishery-independent data was available from the winter acoustic-trawl survey for pollock and the summer longline survey for sablefish.  Additional model developments were presented for Pacific cod and some flatfish stocks.  These changes are highlighted below.

GOA Pollock:  In July 2012 the Center for Independent Experts (CIE) conducted a review of the GOA pollock assessment and a number of their recommendations were included (and future assessments are likely to include more). Three alternative models were presented and performance evaluated. The survey time series in recent years are consistent and show generally increasing trends since about 2007, even though the 2012 Shelikof Strait acoustic survey biomass estimate declined 22% from the 2010 estimate. In contrast, the ADF&G crab/groundfish survey biomass estimate increased by 71% from the 2011 estimate.  The estimated abundance of mature fish in 2013 is projected to be nearly the same as in 2012 and is projected to decrease gradually over the next 5 years. The model estimate of spawning biomass in 2013 is 259,843 t, which is 35.1% of unfished spawning biomass (based on average post-1977 recruitment). 

GOA Pacific Cod:  The 2012 GOA Pacific cod assessment author presented an evaluation of ten alternative models which focused on exploring the effects of different combinations of tuning to survey pre-recruits and larger Pacific cod (>27 cm), separately. Additional issues were related to how the model was fitted to available survey mean length-at-age data.  Estimated age-0 recruitment has been relatively strong since 2005, and stock abundance is expected to be stable in the near term. With projected female spawning biomass in 2013 estimated at 111,000 t, the stock is above the Bmsy proxy of 82,100 t.

GOA/BSAI Sablefish: The longline survey abundance index decreased 21% from 2011 to 2012 following an 18% increase from 2008 to 2011. The assessment model indicates somewhat lower incoming recruitment compared to 2011 estimates and that spawning biomass is projected to decrease from 2013 to 2017, and then stabilize. The estimated spawning biomass in 2013 is about 6% above the Bmsy proxy. (continued)

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