title: Increasing hydrologic variability threatens depleted anadromous fish populations.
abstract: Predicting effects of climate change on species and ecosystems depend on understanding responses to shifts in means (such as trends in global temperatures), but also shifts in climate variability. To evaluate potential responses of anadromous fish populations to an increasingly variable environment, we performed a hierarchical analysis of 21 Chinook salmon populations from the Pacific Northwest, examining support for changes in river flows and flow variability on population growth. More than half of the rivers analyzed have already experienced significant increases in flow variability over the last 60 years, and this study shows that this increase in variability in freshwater flows has a more negative effect than any other climate signal included in our model. Climate change models predict that this region will experience warmer winters and more variable flows, which may limit the ability of these populations to recover.
authors: Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA.
authors: Eric J
authors: EJ
authors: Ward
authors: Washington Department of Fish and Wildlife, 600 Capitol Way N, Olympia, WA, 98501, USA.
authors: Joseph H
authors: JH
authors: Anderson
authors: Fisheries Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA.
authors: Tim J
authors: TJ
authors: Beechie
authors: Fisheries Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA.
authors: George R
authors: GR
authors: Pess
authors: Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA.
authors: Michael J
authors: MJ
authors: Ford
keywords: anadromous fish; climate change; endangered species; environmental variability; hydrologic variability; salmon; winter storms