Predator aggregations during eulachon Thaleichthys pacificus spawning runs

摘要

Predators congregated in large numbers during the 1996 and 1997 spring spawning runs of eulachonThaleichthys pacificus Richardson(Osmeridae)in the lower reaches of the rivers entering Berners Bay, southeastern Alaska. Predator abundance rose rapidly at the beginning of the runs and was significantly correlated with an index of eulachon abundance within years. Gulls(Lar- idea)were the most abundant predators, with a daily average peak of 40 000 during the 1996 run, at a density of 3000 km~-2. A daily average peak of over 250 Steller sea lions eumetopias jubatus and harbor seals Phoca vitulina fed on eulachon early in the run in both years.