Aquatic Ecosystems and Fisheries: Current Research
Effects of Climate on Juvenile Salmon Survival in the Freshwater Environment
Changing hydrologic conditions associated with climate change have the potential to affect freshwater survival of Pacific Northwest salmonids via a number of impact pathways. Habitat conditions mediate the effects of climate, however, so neighboring populations with differing habitat conditions may differ in their responses to climate change. Here, we explore potential differential responses of the viability of four salmon populations in the Salmon River (ID) and Wenatchee River (WA) basins.
For the Salmon River basin populations, we linked predicted changes in air temperature and precipitation from several General Circulation Models to a local hydrological model to project streamflow and air temperature under two climate-change scenarios. We then developed a stochastic, density-dependent life-cycle model with independent environmental effects in juvenile and ocean stages, and parameterized the model for each population. We found that mean abundance decreased 20–50% and the probability of quasi-extinction increased dramatically (from 0.1–0.4 to 0.3–0.9) for all populations in both scenarios. Differences between populations were greater in the more moderate climate scenario than in the more extreme, hot/dry scenario. Model results were relatively robust to realistic uncertainty in freshwater survival parameters in all scenarios.
Our results for the Salmon River basin demonstrate that detailed population models can usefully incorporate climate-change predictions, and that global warming poses a direct threat to freshwater stages in these fish, increasing their risk of extinction. Because differences in habitat may contribute to the individualistic population responses we observed, we infer that maintaining habitat diversity will help buffer some species from the impacts of climate change.
Currently this work is being extended to the Wenatchee basin in eastern WA using fine scale hydrologic models incorporating stream temperature. Fine scale models are also being developed for several specific sub-basins in the Salmon River basin to help extend and refine the previous studies which used the macro-scale VIC model for hydrologic simulations and regression models for stream temperature.
Hydrologic models for individual basins have been constructed and graduate students conducting fisheries research have been trained in their use. Paper documenting this work is in progress.
NOAA Fisheries Northwest Fisheries Science Center, University of Washington Department of Civil and Environmental Engineering
NOAA Fisheries Northwest Fisheries Science Center
For more publications on CIG's research on climate and PNW aquatic ecosystems, please see CIG Publications.