Cooperative Fish and Wildlife Research Units Program: Oregon
Education, Research and Technical Assistance for Managing Our Natural Resources

In the Upper Klamath Basin (UKB), redband trout (Oncorhynchus mykiss newberrii) support the only remaining subsistence fishery for the Klamath Tribes and serve as an important proxy for the conservation of Chinook salmon (O. tshawytscha), a traditional First Food for the Klamath Tribes that is slated for reintroduction after the removal of several downstream dams. While two major conservation plans guide the restoration and management of UKB fisheries, neither plan incorporates disease and invasive species impacts, both of which are critical drivers of the Basin’s ecological balance. This project addresses this gap by examining the role of the parasite C. shasta in influencing species distributions within the Basin. Previous research suggests that C. shasta may confine invasive trout to cooler, spring-fed habitats while allowing native salmonids to coexist under intermediate temperatures. Under certain conditions, C. shasta may act as a “beneficial enemy” by limiting invasive trout presence, indirectly supporting native salmonid populations. For this project, we are analyzing the prevalence of C. shasta, native redband trout, and invasive trout in relation to specific habitat features using spatial data sets, and modeling their distributions based on water temperature and other environmental variables. These findings will inform fisheries risk assessments under future climate scenarios, providing data essential for adaptive management strategies that support the resilience of UKB’s native fish populations and the cultural and subsistence needs of the Klamath Tribes.