Forage Species in Lakes and Reservoirs of the Western United States

Abstract

Fisheries management in the western United States has concentrated on salmonid species, particularly in streams. Forage-fish management in lakes and reservoirs is not highly developed, and has emphasized introductions of both predators and prey. In coldwater lakes, kokanees Oncorhynchus nerka have been established widely as the principal forage for salmonids and often support a sport fishery themselves. Introductions of other forage organisms in coldwater lakes and reservoirs, notably the opossum shrimp Mysis relicta and redside shiner Richardsonius balteatus have had mixed results due in part to food competition with resident species. A variety of exotic predator and prey species have been introduced in coolwater and warmwater reservoirs. Results have varied greatly, and include establishment of successful sport fisheries, elimination of native fishes, failure of introduced predators or prey, and predation on stocked salmonids. Native forage species generally have been overlooked by management, although there appears to be a large potential for their utilization, particularly with coadapted salmonid species. Better screening procedures for exotic introductions and a concerted investigation of the ecological requirements of both native and introduced predator-prey combinations are required for intelligent management of western lakes and reservoirs.