Gray whales and the structure of the Bering Sea benthos.

The purpose of this study was to look at the effect of foraging by gray whales on the benthic community. The gray whale, the only mysticete whale which feeds mainly upon benthic organisms, relies on the amphipod crustacean assemblages of the northern Bering Sea and the Chukchi Sea for most of its annual food intake. Foraging whales leave identifiable depressions 0.6 to 3 m long in the bottom sediments in their wake. Patterns in the infaunal community composition appeared to be correlated with the size of the pit and by inference, the age of the pit. Large, deep pits were characterized by species considered early colonists of disturbed areas. Smaller, shallow depressions did not have elevated numbers of early colonists. Abundance of Ampelisca macrocephala, the dominant bottom organism and whale prey item, was depressed in all pits sampled.