Photo by: Jason Ching

For folks passionate about native fish, the upper Klamath River basin is a prime destination. The degree of endemism, or fish found only in the basin, is remarkable—and other native fish species in the basin display interesting life histories that will intrigue any fish enthusiast.

Redband Trout are perhaps the most diverse fish species in the Klamath basin, in terms of the varying spawning and rearing strategies that they exhibit. They are also the most important recreational game fish and the only remaining subsistence fishery for the Klamath Tribes.

The Williamson and Sprague Rivers and other feeder streams to Upper Klamath Lake are known worldwide for their exceptionally large Redband Trout, which grow to salmon-size thanks in part to Upper Klamath Lake’s enormous productivity. Researchers, fishery managers, and anglers knew that these fish used the lake but the exact timing of that usage and where exactly they moved throughout the system was unknown.

Now, thanks to recent research led by Dr. Jonny Armstrong and PhD student Nick Hahlbeck of Oregon State University, in collaboration with Oregon Department of Fish and Wildlife, the lives of adfluvial Redband Trout in the basin are now better understood (adfluvial describes fish that use a lake for feeding and rearing, but spawn in rivers).

Dr. Armstrong and colleagues found that these large Redband Trout generally spend portions of the winter, spring, and fall in the lake where they achieve most of their annual growth by exploiting favorable conditions. However, over the course of each year, the fish make two migrations to tributary rivers and streams and other coldwater habitats adjacent to the lake: once during summer months to escape poor water quality conditions, and once during the winter or spring for spawning purposes.

This movement between distinct habitat features may provide important insight into how fish populations will adapt their behavior to mitigate impacts of a warming climate on local watersheds.

The work of Armstrong et al also identified important Redband Trout spawning areas that were previously unknown. This has helped landowners and groups like Trout Unlimited and the U.S. Fish and Wildlife Service more efficiently prioritize restoration efforts. Continued research and monitoring of these populations will assist resource managers, Tribes, restoration groups and anglers in protecting and conserving Redband Trout in the upper Klamath basin.