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How Will Coldwater Fish Survive in a Warming Future? Identifying Life-Stage Specific Use of Coldwater Refugia in the Klamath Basin and Willamette River

Principal Investigator
Jonathan Armstrong


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Oregon’s Upper Klamath Basin is one of the warmest watersheds in the Pacific Northwest. Despite its naturally warm waters, the basin supports abundant redband trout. These are some of the largest-bodied trout in the entire U.S., and are a culturally and economically important species, providing the last remaining subsistence fishery for the Klamath Tribes and drawing recreational anglers. The ability of this coldwater species to survive in one of the region’s warmest watersheds could hold valuable clues for conservation in the face of warming global temperatures, which represents one of the biggest threats to North America’s coldwater fish. Previous research has found that redband trout rely heavily on spring-fed habitats. These springs [...]

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Oregon’s Upper Klamath Basin is exceptionally warm, providing a glimpse of what other watersheds could look like after decades of climate change. Despite exhibiting stressful summer temperatures, the Upper Klamath Basin supports abundant redband trout that are some of the largest-bodied trout in the entire US. Beyond the important subsistence and recreational fisheries these trout support, their ability to thrive in one of Oregon’s warmest watersheds may hold valuable clues for conservation. Our research team has found that redband trout rely heavily on spring-fed habitats and migrate long distances to find them, sometimes 100 miles or more. Redband trout move to spring-fed sites to cool-off during summer and also to spawn during winter, but they never use the same site for both purposes. Further, juveniles appear to survive summer in different spring-fed sites than those used by adults. Thus, redband trout move across the seasons and throughout their life to take advantage of a diverse mix of spring-fed coldwater habitats. In order for our fisheries to remain productive, we need to understand and protect the range of habitats that allow coldwater fish to thrive rather than assuming there is a single “best” habitat. This project will translate these new findings into tangible tools for protecting and restoring coldwater habitats to improve fisheries in the Upper Klamath Basin and beyond. We will work with stakeholders to provide maps of existing spring-fed habitats and the life-stages that each of these assets supports, in addition to maps of impaired spring-fed habitats and the life-stages that they would likely support if restored. These products will be integrated into forthcoming conservation plans that will guide major restoration projects in the next ten years.

Project Extension

typeTechnical Summary
valueNaturally warm watersheds can emulate future climate conditions and provide clues as to what habitat features will make coldwater fishes resilient to coming threats. This project uses the Upper Klamath Basin as a model system to address a key knowledge gap identified by the Northwest CSC Science Agenda: how do freshwater refugia scale-up to function at the population level? Leveraging our ongoing field efforts and long-term data from partners, we will compile a unique dataset quantifying how each life stage in a culturally important fish population uses refugia to survive extreme summer heat stress (i.e., water temperatures >25°C). These data will empirically demonstrate the need for coldwater portfolios, diverse aggregates of refugia that allow populations to complete their life cycle in the face of seasonal heat stress. By statistically modeling the habitat features that make refugia functional for each life stage we will provide a novel tool for conservation planning, enabling our partnering stakeholders—Oregon Department of Fish and Wildlife, Trout Unlimited, and the Klamath Tribes—to more strategically predict the biological returns on proposed habitat investments. Our partners will directly incorporate our empirical data and model predictions into two of the most important restoration plans in the western United States, the Upper Klamath Basin Watershed Action Plan, and the Klamath Anadromous Fish Reintroduction Implementation Plan. These plans will guide future restoration and management in the basin, yet they currently lack robust science on fish habitat use in general, and refugia use in particular. We co-developed this proposal with our stakeholders to address these urgent science needs. As well as research applications, this project will support several early-career scientists, a PhD student, and two undergraduate research assistants.
projectStatusIn Progress

Budget Extension

typeAward Type
typeAward Number

Klamath River, Bob Wick, BLM - Credit
Klamath River, Bob Wick, BLM - Credit


Spatial Services

ScienceBase WMS


  • National and Regional Climate Adaptation Science Centers
  • Northwest CASC



Additional Information


Type Scheme Key
RegistrationUUID NCCWSC 0c7a2669-16e5-48db-941b-5a3884cc54a9
StampID NCCWSC NW18-AJ1339

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