The Colorado Department of Wildlife launches kokanee salmon research at Blue Mesa



From The Telluride Watch:

The research will examine several issues: how many kokanee fingerlings are consumed by predator fish on their way to Blue Mesa Reservoir shortly after they’re released from the Roaring Judy Hatchery; the population, life cycle and diet habits of lake trout; the amount of predation by perch which were illegally planted in the reservoir several years ago and have a self-sustaining population; and continued assessment of kokanee population trends. The reservoir is a very productive fishery, upon which the DOW has relied for many years as the primary water for kokanee salmon production in Colorado. But during the last 10 years the kokanee population in the lake has dropped precipitously primarily due to predation by lake trout. Rainbow trout survival has also declined significantly because of lake trout predation.

The first part of the research will look at survival of kokanee fingerlings after they’re released from the Roaring Judy Hatchery. Each spring, some of the fish are eaten by brown trout as they make their way down the East River and Gunnison River and into the reservoir. The young fish were released the evening of April 27 and biologists electro-fished at spots in the Gunnison River on April 28; the stomach contents of the caught brown and rainbow trout caught will now be examined.
 At various locations throughout the reservoir during May, nets will be set to catch other fish, to determine the amount of kokanee they’re eating. All samples will be submitted to researchers from Colorado State University who will conduct a diet analysis.

“The intent of this work is to assess predation on kokanee,” said Dan Brauch, aquatic biologist for the DOW in Gunnison. “The more we can learn about the extent of all predation the better we can manage the reservoir for multiple species.”

More Aspinall Unit coverage here.