Fish assemblages on the southeastern Brazilian Bight, sampled by midwater trawl during spring and summer seasons: species composition, abundance, and environmental drivers

摘要

We provide an overall description of the species composition and abundance of pelagic fish assemblages sampled with midwater trawls at depths 100 m in the southeastern Brazilian Bight (SBB, south-southeastern Brazil) during the spring summer period from 1995 through 2010. We also investigated the effect of 1) 3 water masses, the South Atlantic Central Water (SACW), Coastal Water (CW), and Mixed Water (M), and 2) a set of environmental and spatial variables on the SBB pelagic fish assemblages. The aggregations comprising 43 species, were dominated by highly abundant mid-trophic-level schooling species. The Argentine anchoita (Engraulis anchoita), rough scad (Trachurus lathami), Atlantic cutlassfish (Trichiurus lepturus), and Brazilian sardinella (Sardinella brasiliensis) were the dominant species by biomass. They were distributed widely over the SBB and occurred in all years. Results from multivariate analyses indicate that SACW and the combination of CW and M affected the SBB pelagic assemblage structure and that each contained a specific species grouping, whose abundance changed in relation to depth within the water column and to distance from shore of both SACW and CW+M. This pattern is consistent with the hydrographically complex structure of the SBB in spring and summer.