Assemblages and biogeography of demersal fishes of the east coast of North America

This study describes and maps demersal fish assemblages for the east coast of North America from Cape Hatteras, North Carolina, to Cape Chidley, Labrador, evaluates evidence for interannual shifts in assemblage distribution, and examines the relationship of the assemblages to accepted biogeographical boundaries. Demersal trawl survey data collected from 1975 to 1994 were analyzed. Visual classification of distribution maps for the 108 most abundant demersal species revealed nine species groups, based on both geography and depth distribution. Eighteen assemblage groups were identified using principal components analysis (PCA) and mapped. Assemblage groups were also identified by cluster analysis. Fish assemblages identified by both methods were spatially coherent. Assemblage distribution patterns were not consistent with accepted biogeographical boundaries. The PCA explained only 56.3% of the variance in distribution of the species, indicating that the assemblages should be interpreted as indeterminate, po...