Research Document - 2000/027

Exploratory Jonah Crab, Cancer borealis, Fishery in Lobster Fishing Area 33 (1997 - 1999)

By B. Adams, A. Reeves and R. Miller 

Abstract

The exploratory Jonah crab fishery in lobster fishing area (LFA) 33 has been fished from 1997-99. The fishery was assessed with sea samples, port samples and analysis of mandatory fisher logbooks.

Effort was concentrated along the western and northern edges of LaHave Basin, moving eastward each year. The landings (143 - 167 mt) and CPUE (2.6 - 3.0 kg/th) have changed only marginally from 1997 to 1999. Mean carapace width of male crab (138 - 141 mm) remained stable from 1997 to 1999. Catch composition by number was 11% sub-legal male, 22% female 12% soft-shelled male, and 54% hard-shelled male in 1997 and 1998. Due to a reduction in legal minimum size and size of trap escape gaps, 1999 female crab increased to 29% and sub-legal males decreased to 5%. Bycatch was almost non-existent (e.g., 3 lobsters in 5,675 trap hauls sampled by DFO observers).

Field experiments showed 76 x 150 mm entrance restrictions did not affect bycatch or Jonah catch, handling the catch increased crab mortality, weight of crabs in a box did not affect mortality, and shark bait was superior to pollock frames. Laboratory experiments comparing trap types showed lobster traps performed best.

This fishery operated briefly in 1983 - 84. CPUE was about double and carapace widths were similar to 1997-99.

CPUE and size frequency data suggest that current exploitation levels are not endangering the sustainability of Jonah crab stocks in LFA 33. However, fleet size should be maintained near current levels until a greater proportion of potential Jonah crab habitat has been explored.

Recommended changes in regulations are a minimum legal carapace width of 127 mm, no restriction on retention of females, escape gaps of at least 47.5 mm high, a lengthening of season, and no Jonah bycatch allowed by other fisheries.

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