Food habits, prey selectivity and food resource partitioning of a community of fishes on the outer continental shelf

The demersal fish community of the outer continental shelf in the Middle Atlantic Bight consists of resident species, seasonal species with boreal affinities, and seasonal species with warm temperature affinities. Dominant demersal fishes of the outer continental shelf feed primarily on macrobenthic invertebrates, which persist in dense, stable communities. Some dominant predators also feed heavily on fishes, cephalopods, and planktonic invertebrates, at least seasonally. Food habits of the fishes change seasonally, especially at the species level. Food habits of fishes also change considerably with size, with most predators showing distinct feeding stanzas separated by a marked change in feeding strategy. Electivity patterns of predators upon the benthos were varied with respect to prey distribution and abundance patterns. Some dominant benthic species were not selected as food. Other rarer species were preferentially selected. Some prey species that varied in abundance with respect to habitat strata were eaten in proportion to their abundance in most habitats. Others were eaten only where very abundant, or were consumed in moderate amounts regardless of their abundance in the benthos. Several factors may account for these patterns. Most predator species shared many prey species. Overlap in diet among the predators varied seasonally, with overlap relationships changing as species and size class composition of the predators changed. Intra-specific diet overlap between feeding stanzas was low, but higher interspecific overlap occurred between species of similar size. Dietary overlap was lowest in the spring, when planktonic and nektonic organisms were consumed by most size classes of dominant predators. Although many important prey species were consumed by several predators, some were selectively consumed by only a few predators, so that there was never complete dietary overlap between two species