Classification of Fish Assemblages based on Echo Integration Surveys

Echo integration data typically collected during fish biomass surveys have additional utility in species recognition. Our analysis is based on a rockfish (family Scorpaenidae) hydroacoustic survey off the northwest coast of Vancouver Island, British Columbia, Canada. Survey data from 105 echogram sections were divided into two categories on the basis of ocean bottom habitat. One category corresponded to an area of bedrock outcrops and the other to the continental slope adjacent to the shelf break. Hydroacoustic characteristics of the bottom-oriented fish assemblages associated with these habitats could be described by time of day, mean volume density, dispersion, and mean off-bottom distance of the biomass. Nearest-neighbour analysis of these features classified assemblages into habitat categories with up to 97% success. Between-habitat differences in the assemblages were also evident from concurrent experimental fishing. Different rockfish species dominated the assemblages in the two areas. Our results s...