Sockeye salmon cycles in the Kvichak River, Bristol Bay, Alaska

Summary

The Kvichak sockeye salmon cycle originates in freshwater. It is being maintained by a depensatory mortality exerted by resident predators in off years and by increased survival through biogenic enrichment by salmon carcasses of the oligotrophic nursery areas after peak escapements. The level of predators is controlled during the off years by available prey including juvenile salmon. Hence, ecological stability and cyclic dominance seem to lead to a single peak year in a lake. Because of partly communal nursery areas, the peak years in Lake Clark and Iliamna Lake must be adjacent ones.