Some of the equipment used in the Cultus Lake project.

Determination of Cultus Lake Sockeye Run Timing and Survival

Out-Migrating Smolts and Returning Adults - 2004-2005
Cultus Lake sockeye were classified as “Endangered” by COSEWIC in May 2003. This stock is difficult to protect because it is unclear how the timing of migration overlaps with that of the economically-important, southern British Columbia, sockeye fishery. The Pacific Salmon Commission funded a project to address this issue using acoustic tags implanted in hatchery-reared smolts.

• Video of the Cultus Lake data (MOV Format)

A total of 466 tagged sockeye smolts were released into Sweltzer Creek, immediately downstream of Cultus Lake in May and June of 2005. Using the POST array, the route, timing, and survival of out-migration was measured within Cultus Lake, the lower Fraser River, and the marine environment. Additionally, “sleeper” tags were implanted in the larger smolts and will re-activate in 2007, providing data on the in-migration of adults surviving to return.

Survival was very low in the Fraser River in 2005. Only 10-14% of the tagged smolts left the river to enter the Strait of Georgia-- approximately one-sixth of that observed in 2004. In contrast, ocean survival within the Strait of Georgia was comparable to or higher than that measured in 2004, at approximately 37%. Low survival was not observed in other stocks of the Fraser River. The cause of mortality for the Cultus Lake sockeye is not known, but deserves careful study given the endangered status of this stock.

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