DIETS AND STANDING STOCKS OF BENTHOPELAGIC FISHES AT 2 BATHYMETRICALLY DIFFERENT MIDOCEANIC LOCALITIES IN THE NORTHEAST ATLANTIC

Deep-sea benthopelagic fishes were sampled by trawl and free-fall long line at two latitudinally and bathymetrically separated stations in th e northeastern Atlantic. The catch structure and the contents of the f ish stomachs were analysed. The northern, 3000 m deep station in the I celand Basin exceeded the deeper (4500 m) site in terms of demersal fi sh biomass and abundance by factors of 5 and 10, respectively. Synapho branchidae of the species Histiobranchus bathybius and several species of Macrouridae contributed to the samples, the latter dominating with Coryphaenoides (Nematonurus) armatus most abundant in the north and w ith Coryphaenoides (Chalinura) leptolepis in the south. Diet compositi on were studies for numerical abundance and wet weight of prey organis ms. In the Iceland Basin, where two size classes of C. (N.) armatus co uld be analysed separately, an ontogenetic change in diet was noted. I ndividuals shorter than 30 cm in length fed mainly on benthic and epib enthic Crustacea whereas the larger specimens showed a high proportion of fish and Cephalopoda in their stomachs. At the southern site (BIOT RANS station in the West European Basin) Amphipoda, fish and Cephalopo da were the main food source. Coryphaenoides (Chalinura) leptolepis fe d on Malacostraca and fish at the northern site, but on Polychaeta and Cephalopoda at the southern station. Stomachs of H. bathybius contain ed food only in the Iceland Basin. Their diet consisted mainly of Mala costraca and Cephalopoda. Despite the state of digestion, most Cephalo poda could be identified by means of their beaks, which also allowed a recalculation of their original size. The taxonomic compositions and the size structure led to the assumption that most cephalopoda were ep i- or mesopelagic and had been preyed upon near the bottom as carcasse s. The possible trophic position of the predominant benthopelagic fish es in the benthic boundary layer id discussed.