Using the past as a prelude to the future to assess climate effects on native trout across the United States Active

Future climate change is expected to dramatically alter the structure and function of freshwater ecosystems that support salmonid species. The response of salmonids to climate change will vary through space and time and manifest in both known and currently unknown ways. A potentially rich source of understanding of how salmonids interact with climate lies in a unified retrospective analysis of observed climate and population data in diverse habitats across the United States. Through research and management partners, tens of thousands of sampling events have occurred and continue to occur across the ranges of native salmonid species. This project is capitalizing on existing fish population and climate data from the recent past (1950-current) to: 1) test species-climate hypotheses, 2) identify mechanisms linking species to climate drivers, 3) validate current forecasting models, and 4) improve monitoring programs, vulnerability assessments, and risk assessment tools. An inherent benefit of this approach is the use of empirical climate and species population data, thus minimizing the uncertainty associated with extrapolations and climate projections. Currently, this project is assessing the spatiotemporal spread of invasive hybridization between introduced rainbow trout and native cutthroat trout in the Northern Rockies; conducting a retrospective analysis of how climatic variation and human stressors have impacted bull trout populations; and assessing the invasion dynamics of non-native brown trout in Montana’s rivers and streams.

Funding: USGS National Climate Change and Wildlife Center, USGS Mendenhall Fellowship Program.

Collaborators: Drs. Ryan Kovach, Robert Al-Chokhachy, Ben Letcher, Steven Hostetler, Jeff Kershner (USGS)