Assessment of factors limiting Klamath River fall Chinook salmon production potential using historical flows and temperatures

Product Type: Open-file Report

Year: 2006

Author(s): Bartholow, J.M. and J.A. Henriksen

Suggested Citation:
Bartholow, J.M. and J.A. Henriksen. 2006. Assessment of factors limiting Klamath River fall Chinook salmon production potential using historical flows and temperatures: U.S. Geological Survey Open-File Report 2006-1249. 111 p.

Abstract

We parameterized and applied a deterministic salmon production model to infer the degree to which river flows and temperatures may limit freshwater production potential of the Klamath River in California. Specific parameter requirements, data sources, and significant assumptions are discussed in detail. Model simulations covered a wide variety of historical hydrologic and meteorologic conditions for 40+ years of environmental data. The model was calibrated only qualitatively, appearing to perform well in predicted outmigrant timing, but overestimating growth. Egg-to-outmigrant survival was near that reported for other rivers north of the Klamath River. Predicted production potential appeared to be determined by multiple causes involving both regularly occurring habitat-related constraints and irregularly occurring exposure to high water temperatures. Simulated production was greatest in years of intermediate water availability and was constrained in both dry and wet years, but for different reasons. Reducing mortality associated with limitations to juvenile habitat, if possible, would be expected to have the highest payoff in increasing production. Water temperature was important in determining predicted production in some years but overall was not predicted to be as important as physical microhabitat. No single mortality cause acted as a true “bottleneck” on production…