Demersal fish and cephalopod communities of an unexploited coastal environment in northern Australia

Abstract

Fish communities in the south-eastern Gulf of Carpentaria were surveyed before the development of a demersal trawl fishery for prawns. Distribution data for fish and cephalopods were examined to determine community composition and species-distribution patterns in an unexploited shallow-water tropical fish community. Common species were mostly Indo-west Pacific in affinity, and included many species important in demersal trawl fisheries. Three clusters of site groups were present, comprising site groups from nearshore (~2-5 m), shallow offshore, and deep offshore (~15-35 m) areas, respectively. Site groups did not correspond to clearly defined communities. Species overlaps were frequent. Limits to the distribution of common species seemed to be related more to physical factors (bottom depth, salinity and sediment type) than to other biotic factors (distribution of species). The overall picture was of a rich assemblage of fish species in an environment characterized by gradients rather than by sharp changes.