Project Information

Title: Kenai River Sockeye Salmon Restoration R053

Project Year and Number: 1992: R053

Other Fiscal Years and Numbers for this Project: 1997: 97255-CLO, 1996: 96255, 1996: 96255-1, 1996: 96255-2, 1995: 95255, 1994: 94255, 1993: 93015

Principal Investigator (PI): Ken Tarbox (Alaska Department of Fish & Game)

Managing Agency: ADFG

Assisting Personnel: Linda Brannian, Randall Davis, Jeff Fox, Stephen Fried, Bruce King, David Waltemyer

Research Location: Kenai River

Restoration Category: Damage Assessment

Injured Resources Addressed: Sockeye Salmon

Abstract: Sockeye salmon (Oncorhynchus nerka) which spawn in the Kenai River system were injured by the Exxon Valdez oil spill. Greatly reduced fishing time in the Upper Cook Inlet area due to the oil spill caused sockeye salmon spawning escapement levels in the Kenai River system to exceed the desired amount by three times. The biological impact of the oil spill on Kenai River sockeye salmon stocks is expected to be serious. Data collected by NRDA Fish/Shellfish Study 27, Sockeye Salmon Overescapement, indicated greatly reduced survival of juvenile sockeye salmon during the winter-spring rearing period. The extremely high escapement may have initially produced more rearing juvenile sockeye salmon than could be supported by nursery lake productivity. In general, when rearing salmon abundance greatly exceeds lake carrying capacity, the species and size composition of prey resources are altered, which affects all trophic levels. Because of such changes, juvenile sockeye growth is reduced, freshwater mortality is increased, greater proportions of fry remain in the lake for another year of rearing, and smolt condition is reduced and marine mortality is increased. Limiting sockeye salmon fry production by closely regulating the number of spawning adults may be the only way to restore the productivity of these rearing areas. However, the number of adult sockeye salmon returning from the 1989 escapement may be so low that a severe reduction, or complete elimination, of human use of this species may be necessary starting in 1993 to ensure minimum escapements. The goal of this project is to restore Kenai River sockeye salmon stocks injured by the Exxon Valdez oil spill. This will be accomplished through improved stock assessment capabilities, more accurate regulation of spawning levels, and modification of human use. Restoration of Kenai River sockeye salmon stocks will be achieved when average fry, smolt, and adult production can be maintained. Prey resources of rearing lakes must also be restored to normal levels (This will be monitored under another restoration study, which will be based on information obtained from NRDA Fish/Shellfish Study 27).


Proposal: Not Available

Reports:
Final Report: See Project 94255

Publications from this Project: None Available