Diets and bathymetric distributions of the macrourid fish of the Rockall Trough,northeastern Atlantic Ocean

The Macrouridae are the most common fish caught in demersal trawls on the continental slope and rise of the Rockall Trough. They represented 41% of all fish caught, with Coryphaenoides rupestris amounting to 28% of the catch. No previous study of the trophic interaction of these fish has been made over a wide bathymetric range. Samples were obtained at 250-m intervals of depth between 400 and 2 900 m in the period 1975 to 1981. The stomachs of 5 326 fish belonging to 12 species were examined to define their diets. Eight species are primarily benthopelagic feeders while four are primarily epibenthic feeders. The bathymetric centres of distribution of the populations of the benthopelagic feeding Trachyrhynchus murrayi, Malacocephalus laevis, Coryphaenoides rupestis, C. guentheri, Nematonurus armatus, Chalinura brevibarbis, C. leptolepis and C. mediterranea are different from each other. Similar differences in bathymetric distribution occurred among the epibenthic feeding Nezumia aequalis, Coelorhynchus coelorhynchus, C. occa and Lionurus carapinus. These differences decrease competition among species that exploit similar resources.