Demersal fish fauna of the continental slope off Nova Scotia, Canada, based on exploratory bottom trawl surveys in 1994�95

Abstract

The demersal fish fauna at 900–1800 m depths off Nova Scotia, Canada, is described using data from exploratory bottom trawl surveys conducted in November 1994 and March 1995 by a commercial fishing trawler. Approximately 25 metric tons (39 000 specimens) of demersal fish belonging to at least 82 species were caught, 30% of which had not previously been recorded from the area. However, more than half the catch consisted of the two species Centroscyllium fabricii (black dogfish) and Coryphaenoides rupestris (roundnose grenadier). Catches were higher in the shallower depth strata fished and cluster analysis showed that depth was the primary factor determining species composition of catches. It is suspected, however, that the vessel fished less effectively at depths greater than about 1500 m, contributing to the reduction in catch quantities at these depths. The importance in catches of large bodied species, particularly Chimaeriformes and sharks, contrasts with results from surveys in adjacent areas. This likely reflects the greater fishing power of the vessel/gear used in present surveys rather than real differences in faunal composition. Catches of mesopelagic species during these surveys, and during an earlier deepwater trawling survey in this area, are also described.