Restoration of Fish Populations In a Water Storage Reservoir

Scope of Services:

An innovative coupling of nutrient addition and biomanipulation strategies was applied to successfully restore fish populations in an aging reservoir.  Kokanee and rainbow trout were historically abundant, but the population collapsed over two decades, coinciding with trophic depression and the onset of competition for food with threespine stickleback that were illegally introduced. Treatment resulted in a 94% decline in abundance of the unwanted stickleback due to predation by introduced cutthroat trout, re-establishment of three age classes of kokanee, and sustained abundance of rainbow trout.  The trout supported a revitalized recreational fishery.

Relevance of the Project:

Scope of work was similar to CEAA requirements pertaining to water withdrawals. The treatments that were designed and tested are now core strategies that are required for maintaining lake function along with water withdrawals for power production within the water use permit.