Research Document - 2000/169

Development of a Fishery for Tanner Crab (Chionoecetes tanneri) off the Coast of British Columbia.

By G.D. Workman, A.C. Phillips, F.E. Scurrah, and J.A. Boutillier

Abstract

The deep water Grooved Tanner crab (Chionoecetes tanneri) is being investigated as one of several species proposed as new fisheries off the coast of British Columbia. Investigation of the fishery potential of this species has been following the Phased approach for the provision of scientific information for new and developing fisheries (Perry et al. 1999). Phase 0 (Pillips and Lauzier 1997) and Phase One Framework papers (Boutillier et al. 1998) have been reviewed by the Pacific Scientific Advice Review Committee (PSARC). This paper is a progress report on studies initiated to determine the distribution and abundance of C. tanneri over its entire geographic range off the coast of British Columbia.

The result of a Department of Fisheries and Oceans (DFO) area swept trawl survey and partial results of a distributional trap survey being conducted by the fishery proponents are summarized. Using these two sources of data we calculated biomass estimates for five Pacific Fisheries Management Areas (PFMA) off the west coast of Vancouver Island (WCVI). The mean size at 50 % maturity for male C. tanneri was estimated to be 112 mm from the biological data collected during the DFO trawl survey. This is proposed as an experimental size limit for the species, consequently, biomass estimates were computed for male C. tanneri larger than 112 mm. The total biomass estimate for the five completed areas of the coast is 630 metric tonnes.

A depletion experiment is proposed for one PFMA (Area 125) off the WCVI to test assessment methodology, develop a separate biomass index and investigate population responses to harvesting. We recommend a harvest of 100 metric tonnes of male tanner crab larger than 112 mm from PFMA 125 during this experiment.

Also presented are the results of investigations into the incidental mortalities of C. tanneri in other fisheries. We identify the current deep-water slope rockfish fishery as the most significant source of incidental fishing mortality. An unknown incidental fishing mortality is also attributable to the sablefish trap fishery. Based on the incidental bycatch of C. tanneri by the groundfish trawl fishery in 1999 it is anticipated that this gear type will harvest approximately 120 metric tons of C. tanneri in 2000.

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