Research Document 1997/36

Flatfish stock assessment for the west coast of Canada for 1997 and recommended yield options for 1998.

By J, Fargo

Abstract

Interim assessments were prepared for important stocks of flatfish caught in the B.C. trawl fishery . In the past CPUE from the commercial trawl fishery has been used as a surrogate for stock abundance for the assessments for Area 5A-B rock sole and Area 3C-D and 5C-E Dover sole. However, the behaviour of the fishing fleet has been dramatically altered by changing trip limits and other regulatory measures in recent years and CPUE can no longer be considered a reliable index of relative abundance. Only summaries of the landing statistics are presented for the stocks listed above. Until more comprehensive assessments for these stocks are undertaken the yield options will remain the same as those recommended for the 1997 fishery. The assessments for Area 5C-D rock sole and English sole stocks are based on catch-age analysis and include biological samples collected during the 1996 fishery. Assessments were produced for four species and six stocks.

Petrale sole stocks are at low abundance. Rock sole biomass in Areas 5C-D in 1996 was above the long term average for the last 50 years. The estimate of fishing mortality for the stock in 1996 was below F_0.1. The yield recommendations for this stock in 1998 are unchanged from those recommended for 1997. English sole biomass in Areas 5C-D in 1996 was slightly above the long term average for the last 50 years. The estimate of fishing mortality for the stock in 1996 was below F_0.1 as well. The yield recommendations for this stock for 1998 remain the same as those recommended for 1997. Landings of Dover sole from Areas 5C-E in 1996 were near the longterm sustainable harvest for that stock while effort in 1996 was close to the optimum corresponding to MSY.

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