The Epipelagic Fish Community of Beaufort Sea Coastal Waters, Alaska

Abstract

A three-year study of epipelagic fishes inhabiting Beaufort Sea coastal waters in Alaska documented spatial and temporal patterns in fish distribution and abundance and examined their relationships to thermohaline features during summer. Significant interannual, seasonal, and geographical differences in surface water temperatures and salinities were observed. In 1990, sea ice was absent and marine conditions prevailed, whereas in 1988 and 1991, heavy pack ice was present and the dissolution of the brackish water mass along the coast proceeded more slowly. Arctic cod, capelin, and liparids were the most abundant marine fishes in the catches, while arctic cisco was the only abundant diadromous freshwater species. Age-0 arctic cod were exceptionally abundant and large in 1990, while age-0 capelin dominated in the other years. The alternating numerical dominances of arctic cod and age-0 capelin may represent differing species' responses to wind-driven oceanographic processes affecting growth and survival. The only captures of age-0 arctic cisco occurred during 1990. Catch patterns indicate they use a broad coastal migratory corridor and tolerate high salinities. As in the oceanographic data, geographical and temporal patterns were apparent in the fish catch data, but in most cases these patterns were not statistically testable because of excessive zero catches. The negative binomial distribution appeared to be a suitable statistical descriptor of the aggregated catch patterns for the more common species.