Biogeography of Groundfish Assemblages on the Grand Bank

Abstract

A 16-year time series (1971–82, 1984–87) of data from spring groundfish surveys was analyzed to identify, describe, and map six broad zoogeographic areas on the Grand Bank of Newfoundland, each characterized by a relatively homogeneous and persistent biological composition (a fish assemblage). The boundaries of these areas were strongly aligned with bottom depth and oceanographic features, confirming previous evidence from worldwide studies on the major determinants of the distribution of groundfish on continental shelves. Consideration of their overall biological coherence allowed a merging and reformulation of the original six assemblage areas into four coherent zoogeographic regions. Analysis of catch rates in the two major regions so defined suggested that species composition was relatively stable over time. Whether the Grand Bank assemblages correspond to groups of functionally-linked fishes remains an open question of considerable practical and theoretical interest. The definition of areas where species broadly recur and overlap provides a useful spatial scale for studies at the community level on the Grand Bank and has implications for multispecies management.