Research Document - 2000/052
The Jonah Crab, Cancer borealis, Fishery in Canadian Offshore Lobster Fishing Area 41, 1995 to 1999
By D.A. Robichaud, C. Frail, P. Lawton, D.S. Pezzack, M.B. Strong, and D. Duggan
Abstract
The evolution of an exploratory offshore Jonah crab, Cancer borealis, by-catch fishery is reviewed from its inception during the 1994-95 fishing season (seasons run from October 16 of one year to October 15 of the following year) to the most recent season (1998-99). During 1995, the offshore lobster industry reached an agreement with the Department of Fisheries and Oceans to fish Jonah crab as a by-catch to offshore lobster with its eight fishing vessels. Fishing for Jonah crab was limited to the traditional offshore lobster fishing grounds in 4X, and landings were not to exceed the 720 t quota set for offshore lobster. Offshore lobster traps were to be used and only males larger than 130 mm (carapace width, CW) could be retained.
Fishing effort was concentrated on Georges and Southwest Browns banks during 1994-95, but expanded to cover all offshore lobster assessment areas during the 1996-97 season. Overall catch increased until the 1996-97 fishing season, when the quota was essentially reached at 707 t. From 1996-97 to 1998-99, fishing effort remained relatively constant between 221,385 and 253,051 reported trap hauls. At present, fishing effort is concentrated in Crowell Basin, and on Southeast Browns and Southwest Browns banks. Effort decreased substantially on Georges Bank from initial levels, and landings declined from a high of 322 t in 1996-97 to 47 t in 1998-99. The 1998-99 catch rates were highest in Crowell Basin (4.6 kilograms per trap haul, kg/th), followed by Georges Basin (2.6 kg/th). Overall catch rate peaked during the 1995-96 season at 4.2 kg/th, then fell to a relatively constant level (from 2.9 to 3.2 kg/th) during the last three fishing seasons.
Average size of crabs measured at sea varied between areas and between months and did not show any clear annual or seasonal trend. The percentage of legal size male crab varied between 54 and 92%, and was generally highest in Crowell Basin.
The recent decline in landings and catch rate on Georges Bank, and to a lesser extent on Southeast Browns Bank, is attributed to a shift of effort to the more lucrative lobster fishery. Potential interaction with the developing inshore exploratory fishery for Jonah crabs, and the by-catch provision for this crab in the inshore lobster fishery, is discussed. Biological and fishery information indicates that a cautious approach should be taken if the long-term goal is to maintain a fishable stock. The catch rates, behavior of the fishery, and the size structure of the stock should continue to be monitored through logbooks, dockside monitoring and at-sea sampling.
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