Demersal fish assemblages of the continental shelf off Colima and Jalisco, Mexico (spring, 1995)

The structure of the soft-bottom demersal fish assemblages of the continental shelf off Jalisco and Colima, Mexico, was studied in an area of 410 km(2). The classification of the 32 most abundant species resulting from the cluster analysis shows eight groups (three from the inner shelf, four from the intermediate shelf and one from the slope shelf). The ordination through detrended correspondence analysis (DCA) defined seven units; the affinity and composition of these units were similar to that of the other technique. The multiple contrasts of the analysis of variance, using the depth/temperature/salinity scores, were significantly correlated with the group of stations and with the eigenvalues calculated for the species with the DCA. This confirms the presence of a bathymetric/thermic gradient and that the shallow thermocline has a segregation effect on the demersal assemblages of soft-bottom fishes.