Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4186
Title: Interactive impacts of water diversion and climate change for juvenile Chinook salmon in the Lemhi River
Author: Annika W. Walters, K. K. Bartz, Michelle M. McClure
Publication Year: 2013
Journal: Conservation Biology
Keywords: Oncorhynchus tshawytscha, Endangered Species Act (ESA), low flow, carrying capacity, juvenile survival,

Freshwater habitat alteration contributes to salmon declines across the Pacific Northwest. In the Lemhi River, Idaho, water diversion causes shifts in the quantity and timing of stream flow, and climate change will further impact stream flow and temperature. Shifts in flow and temperature regimes can influence juvenile salmon growth, movement, and survival. We examined the potential impacts of water diversion and climate change on juvenile Chinook salmon survival and carrying capacity in the Lemhi. Spring flow and summer temperature were good predictors of juvenile survival, with higher flow and lower temperatures associated with increased survival. Water diversion decreased predicted juvenile survival by 75% due to lowered flow, while climate change scenarios led to further reductions in survival, ranging from 48 to 69% in a 30 year time frame, primarily due to increased temperatures. Carrying capacity estimated under diverted flows was 21 to 53% lower than under undiverted flows. Incorporating climate change produced additional decreases in capacity for the drier of 2 climate models examined. Together, these results indicate that climate change will likely pose an additional stressor that must be considered when evaluating the effects of anthropogenic actions (positive or negative) on salmon population status. Thus, this type of analysis will likely be critical for informed conservation decision-making, particularly that which seeks to mitigate the negative impacts of human activities.

Theme: Recovery, Rebuilding and Sustainability of Marine and Anadromous Species
Foci: Describe the relationship among human activities and species stock status, recovery, rebuilding and sustainability.
Characterize vital rates and other demographic parameters for key species, and develop and improve methods for predicting risk and viability/sustainability from population dynamics and demographic information.