Rockfish (Scorpaenidae) Assemblages of Trawlable and Untrawlable Habitats off Vancouver Island, British Columbia

Abstract

Abstract We compared assemblages of demersal rockfishes (Scorpaenidae) associated with two areas of the continental slope off northern Vancouver Island, British Columbia, Canada. Twenty and 21 sets of sunken gill nets were completed on trawlable and untrawlable areas, respectively. The species assemblages on the two areas were markedly different, as demonstrated by their diversity, evenness, and percent similarity and by cluster analysis. On the trawlable area, the catch was numerically dominated by Pacific ocean perch Sebastes alutus (37.6%), splitnose rockfish S. diploproa (23.5%), greenstriped rockfish S. elongatus (12.7%), and bocaccio S. paucispinis (7.3%). This contrasted with the untrawlable area, where the catch was numerically dominated by sharpchin rockfish S. zacentrus (70.8%), and redbanded rockfish S. babcocki made up half (14.5%) the remaining catch. We found no evidence to support the claim by some fishermen that exploited rockfishes on trawlable areas, especially Pacific ocean perch, are m...