Research Document - 2007/017

An assessment of the snow crab resident on the Scotian Shelf in 2006

By Choi, J.S. and B.M. Zisserson

Abstract

For the 2006 fishing season, landings of snow crab were 486 and 4486 t for N-ENS and S-ENS, respectively. Relative to 2005 landings, this represents a decline of 14% and 30%, respectively. These declines were due to reductions in TACs, both of which were attained. Most landings were obtained from offshore areas. Average nonstandardised catch rates were 35.6 kg/trap and 90.6 kg/trap for NENS and S-ENS, respectively. N-ENS catch rates increased 16% relative to 2005 levels while those of S-ENS decreased by 17%. The increase in catch rates for N-ENS was largely due to the re-distribution of fishing effort away from areas of low catch rates to those with higher catch rates in the 2006 season. The offshore slope areas in S-ENS were minimally exploited.

Mature female numbers have increased as the leading edge of immature female pulses have begun to mature. Mature male numbers have declined, resulting in increasingly more balanced sex ratios. The fishable biomass in N-ENS declined 50% from 1,460 t in 2005 to 720 t in 2006. In S-ENS, the fishable biomass increased (10%) for the first time since 2001: from 23.4 x10³ t in 2005 to 25.4 x10³ t in 2006. Recruitment to the mature fishable biomass is expected for S-ENS in 2007 and for N-ENS in 2008. The 2007 season should see the beginning of a recovery of the fishery in S-ENS. The short-term future of the fishable biomass in N-ENS is uncertain. The medium term prospect for ENS in general is positive, if moderate exploitation rates are adopted. Soft-shell incidence will become increasingly an important issue as recruitment continues.

Due to positive signs of recruitment, fishable biomass and female reproduction in S-ENS, a statusquo to marginal increase in TAC is advised. Due to negative signs in fishable biomass and delayed recruitment of immature snow crab in N-ENS, a decrease in TAC is advised.

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