Research Document - 2010/123

Status of Cultus Lake Sockeye Salmon

By M.J. Bradford, J.M.B. Hume, R.E. Withler, D. Lofthouse, S. Barnetson, S. Grant, M. Folkes, N. Schubert, and A-M. Huang

Abstract

The sockeye salmon (Oncorhynchus nerka) population from Cultus Lake, British Columbia, was assessed as endangered in 2003 as a result of a long term decline in abundance that began in the 1970s. Recovery measures that include a conservation breeding program, harvest management and a predator control program in Cultus Lake have been implemented. This report reviews the current status of the population and the efficacy of the recovery measures. We found that that status of the population has not improved since 2003 largely because of poor smolt-recruit survival, and the average number of spawners remains at about 1000 fish. Harvest rates have been reduced since the 1990s and the predator control program appears to have increased the survival of juveniles in the lake. Supplementation releases of juveniles from the captive breeding program to the lake have resulted in increasing numbers of returning hatchery adults, but their success as spawners in the wild remains unknown. Modelling suggests that under the current low smolt-recuit survival rates, recovery is only possible with the successful implementation of all recovery measures. We conclude that the recovery of the Cultus Lake sockeye salmon population is highly uncertain and that continued monitoring is needed to determine if the recovery actions are indeed reducing risks to the population.

Complete document (PDF, 487 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.