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USGS Mendenhall Postdoctoral  Research Fellowship Program

14-24. Using the Past as a Prelude to the Future to Improve Assessments of Climate on Native Salmonids across the United States

We are seeking a postdoctoral candidate to develop a research project that will contribute to a broader retrospective analysis aimed at evaluating the ability of our forecast models to “backcast” possible climate-effects on inland salmonids of the United States.  This analysis may be possible because historical data for streamflows, stream temperature and long-term salmonid population data exist in a number of watersheds throughout the country.  Rather than providing tools to forecast distant future conditions, the intent of the research is to help managers plan for the next 5 to 10 years using the past as a guide to the future. The results of this analysis will serve to: 1) inform managers as to how climate has affected their current management scenario, 2) identify what climate conditions might lead to accelerated changes in species and habitat interactions, and 3) guide conservation and restoration activities in key areas and 4) improve our bioclimatic models.

Salmonids are often considered to be a keystone species for aquatic and terrestrial ecosystems, and are an important early warning indicator of ecosystem health in the face of climate change. Although the potential threats from climate change are now widely recognized, we are now starting to see the consequences of changes that have occurred over the last 50 years.  Salmonids are especially vulnerable to climate-induced warming in freshwater ecosystems because: 1) they require streams and lakes with cold, high quality habitats, which are easily fragmented by thermal or structural barriers; 2) their distributions and abundances are strongly influenced by temperature and stream flow gradients; and 3) they have narrow tolerances to thermal fluctuations in cold waters. Moreover, many native salmonid populations are already small, highly fragmented and isolated from genetic exchange, thereby increasing their vulnerability to stochastic disturbances (e.g., wildfire and debris flows) due to limited ability to adapt through migration.

Our previous work has focused on predicting the effects of climate change on key habitat characteristics that may be altered under different climate change scenarios. These include potential increased summer water temperatures, increased fall and winter flooding, reductions in summer base flows, and increased risk of disturbance events, such as wildfire and debris flows. We have developed predictive bioclimatic models that link contemporary patterns of occurrence and abundance to stream conditions derived from hydrologic and temperature modeling (Isaak et al. 2010; Jones et al. 2013; Al-Chokhachy et al. In press).  Our models suggest potentially large reductions in native trout across the Rocky Mountains during this century, but lack details regarding how changes will manifest in different watersheds (Isaak et al. 2012).

We hypothesize that combined analysis of historical population monitoring datasets (e.g., abundance, distribution, genetics) along with climate, stream temperature and discharge and disturbance data can be used to reconstruct and quantify climate-driven population dynamics of salmonids over the past 20-50 years in selected, data-rich watersheds.  Applicants are encouraged to develop a research approach that relies on advanced quantitative methods for time series data that are needed in the joint analysis of the diverse data sets.  Successful completion of the reconstructions will form the basis for vulnerability assessments that provide information regarding where conservation actions are taken to maximize population resilience and resistance. The reconstructions will also provide a much-needed framework for both testing our forecasting models and for improving and expanding the models to incorporate additional climate-related processes.

The postdoctoral fellow will have access to existing datasets that have been collected for multiple projects that address the effects of climate change on western native trout across multiple states and jurisdictions. The analyses, modeling and forecasting of this project will be undertaken in collaboration with a multidisciplinary research group that brings decades of knowledge to the issue.  The successful candidate will also actively participate in a larger consortium that includes researchers from various state, federal and non-governmental organizations across the western United States.


Al-Chokhachy, R., J. Alder, S. Hostetler, B. Gresswell, and B. Shepard. In press. Thermal controls of Yellowstone cutthroat trout and invasive fishes under climate change. Global Change Biology.

Isaak, D.J., C.H. Luce, B.E. Rieman, D.E. Nagel, E.E. Peterson, D.L. Horan, S. Parkes, and G.L. Chandler. 2010. Effects of climate change and wildfire on stream temperatures and salmonid thermal habitat in a mountain river network. Ecological Applications 20:1350-1371.

Isaak, D.J., C.C. Muhlfeld, A.S. Todd, R. Al-Chokhachy, J. Roberts, J.L. Kershner, K.D. Fausch, and S.W. Hostetler. 2012. The past as a prelude to the future for understanding 21st-century climate effects on Rocky Mountain trout. Fisheries 37:542-556.

Jones, L.A., C.C. Muhlfeld, L.A. Marshall, B.L. McGlynn, and J.L. Kershner. 2013. Estimating thermal regimes of bull trout and assessing the potential effects of climate warming on critical habitats. River Research and Applications DOI:10.1 002/rra.2638.

Proposed Duty Station: Bozeman, MT; West Glacier, MT

Areas of Ph.D.: Fisheries, aquatic ecology, ecology, ecological modeling, biology (candidates holding a Ph.D. in other disciplines but with knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet one of the following qualifications – Research Ecologist, Research Fishery Biologist.

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of theposition will be made by the Human Resources specialist).

Research Advisor(s): Jeff Kershner, (406) 994-5304,, Clint Muhlfeld, (406) 888-7926,; Robert Al Chokhachy (406) 994-7842,, Steve Hostetler (541) 737-8928,, Greg Pederson (406) 994-7390,

Human Resources Office Contact: Lisa James, (916) 278-9405,

Go back to Summary of Opportunities

U.S. Department of the Interior, U.S. Geological Survey
URL: Kershner.htm
Direct inquiries to Rama K. Kotra at
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Last modified: 19:09:57 Tue 23 Jul 2013
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