Journal of the Marine Biological Association of the United Kingdom

Research Article

Fish assemblages on the slope in the Catalan Sea (western Mediterranean): influence of a submarine canyon

Constanti Stefanescu c1, Beatriz Nin-Morales c2 and Enric Massuti c3

Abstract

The analysis of 35 bottom trawls taken on the slope in the Catalan Sea (western Mediterranean) has shown the existence of two different demersal fish assemblages occurring on the upper (350–650 m) and middle (1150–1300 m) slope. The middle slope assemblage is characterized by much higher values in some ecological parameters such biomass and mean fish weight, resulting from the dominance of middle to large size species (e.g. Alepocephalus rostratus, Trachyrhynchus trachyrhynchus, Mora mom). On the upper slope two different stations were considered, one inside and the other outside a submarine canyon. Only slight differences were found in species composition, and hence sample and species were not clearly separated by a correspondence analysis. However, some interesting ecological differences exist between these two stations. Much higher values in abundance and biomass inside the canyon were indicative of higher food availability there. Moreover, a drop in mean fish weight was also noted inside the canyon. The analysis of size distributions in the commonest species along the upper slope showed that the submarine canyon acts as a recruiting ground for some of them.

Correspondence:

c1 Instirut de Ciencies del Mar-CSIC, Passeig Nacional s/n, 08039 Barcelona, Spain

c2 Institut d'Esrudis Avanqats de les Illes Balears, Campus Universitari, 07071 Palma de Mallorca, Spain

c3 Centre Oceanogràfic de les Balears-I.E.O., Apartado 291,07080 Palma de Mallorca, Spain