Demersal fish assemblages and habitat characteristics on the continental shelf and upper slope of the north-western Mediterranean

Continental shelf and upper slope fish communities were studied along the C atalan coast based on 66 experimental bottom otter trawls. A total of 79 de mersal fish species were studied by means of cluster analysis and multi-dim ensional scaling (MDS) ordination for community structure. Analysis reveale d the existence of five major location clusters. Similarity percentage anal ysis (SIMPER) was determined by comparing the dissimilarity between two gro ups of samples using the discriminating species. Geomorphological character istics, bottom substratum and depth showed direct influences on species ass emblages. High correlation between the biotic data samples and depth was ob served. The fish species assemblages identified five main demersal fish ass ociations which corresponded with the five location clusters and with five benthic sediments (mud of the upper slope, sand and gravel, mud of the shel f muddy-sand and sand with rocky outcrops).