Research Ecologist, Northwest Fisheries Science Center, NOAA Fisheries
Unraveling Effects of Climate Change on Freshwater Stages of Columbia River Salmon
Climate affects organisms through an intricate web of ecological interactions and evolutionary responses, all mediated by local habitats. With collaborators at the NWFSC, I have explored some of these interactions and population-specific environmental sensitivities in Columbia River salmon. Because of the complex life history of salmon, each life stage confronts unique environmental challenges. Recognizing this complexity, we have focused on identifying life-stage-specific and population-specific responses of Columbia River spring/summer Chinook and sockeye salmon to variation in climate. Based on a unique 20-year PIT-tag study of 13 Snake River Chinook populations, we identified strong but complex effects of variation in temperature and flow on juvenile growth and survival. We have linked these patterns in survival to hydrological projections of climate change in these streams, and used life-cycle models to evaluate potential consequences of climate change for population viability. Scenarios of climate change produced declines in abundance and increases in extinction risk in all populations, but the relative risks among populations depended on the climate change scenario. Shifting to the adult stage, I explored the history of upstream migration timing in sockeye salmon. Sockeye salmon now enter the lower Columbia River ~11 days earlier, on average, than they did in the 1940s. Based on recent studies of migration survival at various river temperatures and 60 years of daily fish counts and temperature, I developed a model to simulate historical selection pressure. When combined with plastic responses to yearly variation in environmental conditions, this model greatly improves our ability to predict variation in return timing. I am currently working on uniting evolutionary and plastic responses to environmental conditions throughout all freshwater stages into a single model to predict how climate change will modify the fitness landscape. Ultimately, the extent of changes in climate and community dynamics will determine which salmonid life histories remain viable in the Columbia River Basin.
I received a Bachelor's degree from Harvard College and a Ph.D. from the University of Washington, Department of Zoology. I then completed a Post-doctoral Fellowship at the University of Chicago before joining NWFSC in 2004. I concentrated on the effects of climate change on butterfly ecophysiology and range shifts, before addressing these same issues in Pacific salmon.
My primary research goal since coming to NWFSC is to quantify the effects of climate change on population viability of Pacific salmon, considering both ecological and evolutionary responses. To do this we have been working on describing the sensitivity of juvenile freshwater growth, survival and migration timing of Snake River Chinook salmon, primarily, to environmental conditions, and projecting the impacts of climate change on population viability. I am currently extending this project to include impacts on adult migration timing and pre-spawn survival in various Columbia River salmonids.
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