Atlantic Fisheries Research Document 1996/138

Review of the Canadian offshore exploratory fishery for redcrab, Chaceon quinquedens

By D.R. Duggan; P. Lawton

Abstract

The catch history and management framework for an exploratory offshore fishery for the red crab, Chaceon (=Geryon) quinquedens, in Canadian waters of the Scotian Shelf and Georges Bank is reviewed from the inception of sporadic trapping in the late 1960s to the current development phase which has five exploratory licenses. The offshore red crab fishing grounds are now considered to be fully exploited, based on examination of monthly landings, and catch rates from log books, sales slips, and dockside monitoring documents, together with sampling of commercial catch length frequencies, mainly from port sampling.

Catch rates (CPUE) decreased progressively from initial levels of up to 20 kg per trap haul (kg/th. Total effort has increased, particularly in 1995 and 1996, where between 10,000-20,000 trap hauls were made monthly in the spring (April-July). As compared to approximately 5,000 trap hauls per month in previous years. While average size (carapace width, CW) of crab measured in port samples has not declined since the fishery began, crab landed form Emerald and LaHave banks tends to be smaller than that from Georges and Browns banks.

The original commercial biomass estimate, and total allowable catch (TAC) of 1,300 metric tonnes (mt) under which the current fishery operates did not consider Georges Bank. If landings from Georges Bank are excluded (Approximately 30% of current landings), expanded levels of fishing effort in the areas of initial biomass estimation have not yielded landings anywhere near original expectations. Preliminary resource surveys and initial catch rates on LaHave Bank indicate that red crab will enter traps in high numbers, so current low monthly CPUEs and annual landings may reflect lower population abundance and unrealistic assumptions in the original scientific assessment. While the harvest experience to date indicates the potential for a permanent fishery, conversion of existing exploratory licenses to permanent ones is considered premature in 1997. This fishery should be managed conservatively, perhaps with a precautionary cut to the existing TAC to better match the emerging landings pattern. a revised TAC cannot presently be determined on a biological basis until additional information on red crab biology and stock dynamics becomes available.

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