Research Document - 2000/170

Assessment of Pacific Cod in Hecate Strait, Nov. 2000

By A.F. Sinclair

Abstract

Annual total allowable catches (TACs) were introduced for this stock in 1992. The 1992 landings exceeded the TAC by about 50%. Since then, the landings have been below the TAC with between 41% (1994) and 85% (1998/1999) of the TAC being landed. In 1999/2000, 58% of the TAC was landed and so far in the current fishing year, only 31% of the TAC has been landed (as of Nov. 2). Two stock biomass indices were calculated using commercial fisheries data. One covered the period 1954-1995 and was based on quarterly commercial catch per unit effort, an index of stock density (t·hr^-1). The second index covered the period 1994-2000 and was based on a swept area method and used estimates of both density and area fished to produce an index of stock biomass. The indices indicated three periods of high Pacific cod biomass in area 5CD, the mid-1960s, mid-1970s, and the late 1980s. The last peak was followed by a decline to a minimum in 2000. The set-by-set database of fishing activity in area 5CD between 1991-2000 was examined for evidence that the fleet had changed fishing location and depth to avoid cod habitat thus biasing the relationship between the commercial indices and stock biomass. There was little evidence that fishing effort has shifted away from areas preferred by cod. In fact, there may have been an increase in fishing effort in Pacific cod habitat in recent years. A surplus production model was used to estimate key stock parameters including biomass trends, fishing mortality, and biological reference points (F_msy and B_msy). The results indicate that the stock is currently at an extremely low biomass, about 3% of the optimal level. Despite low catches in recent years, the current level of exploitation may not be sustainable and will certainly not allow any appreciable stock recovery. Substantial reductions in catch are required to allow stock rebuilding.

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