Research Document - 2007/006

Trends in Groundfish Bottom Trawl Fishing Activity in BC

By Sinclair, A.

Abstract

Changes in the spatial extent of the BC groundfish bottom trawl fishery were estimated using fishery observer data. The time period 1996-2005 was chosen for detailed analysis since this is the period for which suitable detailed catch and effort data are available from fishery observers. Tow locations were represented by a vector between the start and end points of the tow. Areal estimates were based on a relatively fine spatial grid of 1 km². The implications of these choices on the results of the analysis are discussed. There was virtually no groundfish bottom trawl fishing effort reported from depths greater than 500 m prior to 1990. There has been an extension of the fishery into this depth zone since then. The largest expansion in area fished in the 1996-2005 period was in deep water (>500m) where the longspine thornyhead fishery has developed. There was a considerable increment in cumulative area fished in 2000, the year the longspine thornyhead fishery expanded to northern waters in Triangle (5AB) and Rennell Sound (5E). A second area of expanded fishing is northeast of Middle Bank. This area yielded the majority of reported catches of species associated with corals and sponges. The annual area fished in 0-150 and 150-500 m coastwide either declined or was stable. There was a considerable reduction in the annual area fished in area 5CD in the 0-150 m depth range. There remain considerable areas that have not been trawled since 1996. These are dominated by rough bottoms not suitable for trawling. There are hook and line and trap fisheries in these areas. Little is known about the habitat forming biota in these areas, species compositions, and demographic profiles of the inhabitants.

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