Factors influencing the survival of outmigrating juvenile salmonids through multiple dam passages: an individual-based approach

Ecology and Evolution
Timothy ElderAngela L Strecker

Abstract

Substantial declines of Pacific salmon populations have occurred over the past several decades related to large-scale anthropogenic and climatic changes in freshwater and marine environments. In the Columbia River Basin, migrating juvenile salmonids may pass as many as eight large-scale hydropower projects before reaching the ocean; however, the cumulative effects of multiple dam passages are largely unknown. Using acoustic transmitters and an extensive system of hydrophone arrays in the Lower Columbia River, we calculated the survival of yearling Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) passing one, two, or three dams. We applied a unique index of biological characteristics and environmental exposures, experienced by each fish individually as it migrated downstream, in order to examine which factors most influence salmonid survival. High outflow volumes led to involuntary spill in 2011 and created an environment of supersaturated dissolved gas concentrations. In this environment, migrating smolt survival was strongly influenced by barometric pressure, fish velocity, and water temperature. The effect of these variables on survival was compounded by multiple dam passages compared to fish passing a sing...Continue Reading

References

Dec 13, 2005·Biological Reviews of the Cambridge Philosophical Society·David DudgeonCaroline A Sullivan
Dec 7, 2007·Ecology·D Richard CutlerJoshua J Lawler
Jul 9, 2008·The Quarterly Review of Biology·Julian D OldenN LeRoy Poff

Methods Mentioned

BETA
PCA

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