Research Document - 2002/011

Assessment of the 2001 Snow crab (Chionoecetes opilio) fishery off eastern Nova Scotia (Areas 20 to 24)

By M. Biron, L. Savoie, R. Campbell, E. Wade, M. Moriyasu, P. DeGrâce

Abstract

In 2001, compared to 2000, mean catch-per-unit-effort (CPUE) increased in eastern Nova Scotia (ENS) in Crab Fishing Areas (CFA) 20, 21, 22, 24 and all sub-areas in CFA 23 except 23D. As in 2000, the magnitude of certain increases in CPUEs may be considered 'inflated' by factors such as gear type, soak time, fishing season and pattern, and crab movement. Landings in ENS were 9,917 t in 2001 (excluding the exploratory trap survey on the slope of the Scotian Shelf). Trends in CPUE in all CFAs since 1995 did not suggest any stock decline. Better coverage from at-sea sampling showed high levels of commercial-sized soft and white crab categories appeared in the catches after the month of August in most areas.

Trawl survey data clearly indicated that recruitment to these fisheries and mature females have been consistently decreasing since the survey began in 1997/98. In northern ENS (CFAs 20, 21 and 22), a new relative abundance index will be established based on a trawl survey to be conducted in September instead of May, as in previous years. An experimental trawl survey in the fall of 2001 has indicated that the decreasing trend in immediate recruitment in northern ENS might have been accentuated by the timing of the survey (earlier starting dates) combined with seasonal crab movement. In southern ENS (CFAs 23 and 24), sources of underestimation have been eliminated from the biomass estimation process, while known sources of mortality were better accounted for. This has resulted in a relative abundance index that best represents the snow crab population, but it was also less conservative (i.e. with less sources of underestimation being ignored as in the past) compared to previous years. Commercial-sized male categories observed before the fishery in 2001 were similar to those of 2000. A decreasing trend in both recruitment and commercial-sized adult crab should be considered when managing the northern and southern ENS stocks in coming years.

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Document Text, Tables, and Figures 1-20 (PDF, 3,300 KB)

Figures 21-37, Appendices (PDF, 2,900 KB)

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