Aquatic Ecosystems and Fisheries: Current Research

Quantitative Tools for Evaluating the Effects of Climate Change on the Population Dynamics of Pacific Salmon



Climate variations during the 20th century are now a widely recognized driver of Pacific salmon production. In all likelihood, future changes in climate will continue to structure the population dynamics of Pacific salmon. At this time, however, there is a distinct lack of stock specific information on climate impacts over the entire life-cycle of Pacific salmon as most studies concentrate on either the marine or freshwater environments. To date, nobody has explored the interplay of climate change in the oceans, atmosphere, and continental land mass on the population dynamics of Pacific salmon. Therefore, quantitative models linking existing climate change scenarios to changes in Pacific salmon demographics over their entire life cycle are now needed to assess future climate impacts on the viability of salmon populations throughout their range.

The initial focus of this work is on patterns of covariations in time series of marine survival rates for populations of coho salmon originating in Washington State. Marine survival estimates for more than 14 years for 25 rearing locations are available over the time period from 1970-2004. Our analysis reveals that western Washington coho populations exhibit a diversity of marine survival responses to common climate forcing, and that coherence in marine survival rates among Washington coho populations is in part related to oceanographic domains. Populations entering Puget Sound and those migrating directly to the Pacific Ocean on the Washington coast represent two separate marine survival groups. These results highlight the fact that biodiversity in salmon populations related to the marine part of their life cycle plays an important role in regional scale salmon productivity, and that this marine biodiversity is dependent in part upon freshwater rearing conditions and/or population origin. Our next step is to investigate relationships between the patterns we have observed in marine survival rates and environmental and biological time series that represent ecologically significant aspects of coho marine ecology.

Our analysis adopts a life-cycle modeling framework that will allow us to project future population trajectories and estimate viability measures such as annual growth, mean abundance, and probability of extinction. Then, we will incorporate various regional climate change scenarios to develop scenarios for future ocean conditions and for stream temperature and flows. Finally, we will estimate how salmon population viability will respond to climate change scenarios.


NOAA Fisheries Northwest Fisheries Science Center

Primary Funding

NOAA Fisheries and Their Environment (FATE) program

Related Publications

For more publications on CIG's research on climate and aquatic ecosystems, please see CIG Publications.