Research Document 1998/101

Assessment of the 1997 snow crab (Chionoecetes Opilio) fisheries off eastern Nova Scotia (Areas 20 to 24(and 4X)), Canada

By M. Biron, M. Moriyasu, E. Wade, P. DeGrace, R. Campbell, and M. Hébert

Abstract

The 1997 total landings in eastern Nova Scotia were 12% higher than those of 1996. There was a 25% increase in the seasonal catch-per-unit-of-effort (CPUE) and a 10% reduction in total fishing effort compared to last year. The increase in landings was mostly the result of the 80% increase in landings observed in Area 22, raising from 189 t in 1996 to 343 t this year. In Area 21 fishers met their quota this year, representing a 7% increase in landings over 1996. Although Areas 23 and 24 respectively experienced a 12 and 20% decrease in seasonal CPUE and a 20 and 25% increase in total fishing effort, the overall picture for eastern Nova Scotia fisheries are strongly influenced by the marked increase in seasonal CPUE and decrease of effort in Areas 20, 21 and 22.

The first comprehensive trawl survey was carried out in eastern Nova Scotia in 1997. The initial data collected are good and the trawl survey method could be useful for managing eastern Nova Scotia stocks. However, fishery parameters estimated from this survey are not considered reliable now because of uncertainties, such as the relationship between carapace size and weight which are borrowed from the southern Gulf of St. Lawrence (GSL), an area with different temperature and growth characteristics. Furthermore, discriminant functions used to separate crabs into the adolescent or adult categories were calculated from data collected in the inshore fishing grounds of Areas 22 and 23, based on the discriminant function used in the southern GSL. In addition, the substrate and bottom configuration found in eastern Nova Scotia is quite different than what is found in the southern GSL where this method was developed. These uncertainties are discussed, and recommendations are made for next year's survey. In the meantime, the management of this fishery must still primarily rely on the assessment based on the fishery related data.

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