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Research Document - 2012/080

The 2011 assessment of the snow crab (Chionoecetes opilio) stock in the southern Gulf of St. Lawrence (Areas 12, 19, 12E and 12F)

By M. Hébert, E. Wade, M. Biron, P. DeGrâce, J.-F. Landry, and M. Moriyasu

Abstract

The 2011 assessment of the southern Gulf of St. Lawrence (sGSL) snow crab, Chionoecetes opilio, stock (Areas 12, 19, 12E and 12F) is presented. Snow crab management Areas 12, 19 12E and 12F comprise a single biological population and the sGSL stock is considered as one unit for assessment purposes. The 2011 assessment was conducted according to recommendations from the Snow Crab Assessment Methods Framework Science Review held during November 21 to 25, 2011, in Moncton N.B. The major changes to the assessment methodology were the expansion of the biomass estimation polygon (now between 20 to 200 fathoms) to better cover the sGSL biological unit and the use of catches in weights directly to estimate biomass. The change in methodology required a recalculation of the time series of biomass estimates for 1997 to 2010, exploitation rates, and the Precautionary Approach (PA) reference points. The exploitation rate of the 2011 fishery in the sGSL was 29.9%. The 2011 post-fishery survey biomass of commercial-sized adult male crabs was estimated at 63,162 t (95% C.I. 55,965 to 71,022 t), an increase of 76% from 2010. The available biomass for the 2012 fishery, derived from the 2011 survey, is within the healthy zone of the PA Framework. The residual biomass (33,768 t) from the 2011 survey increased by 119% compared to 2010. Forty seven percent (47%) of the 2011 survey biomass, available for the 2012 fishery, is composed of new recruitment (29,394 t). The recruitment to the fishery in 2011 increased (44%) relative to the 2010 survey. An increasing trend in recruitment of commercial-sized adult male crab to the fishery is anticipated into the 2014 fishery. A risk analysis of catch options relative to reference points for the 2012 fishery is provided.

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