Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8948
Title: Relationships between Chinook salmon swimming performance and water quality in the San Joaquin River, California
Author: Brendan Lehman, David D. Huff, Sean A. Hayes, Steven T. Lindley
Publication Year: 2017
Journal: Transactions of the American Fisheries Society
Volume: 146
Issue: 2
Pages: 349-358
Keywords: Chinook salmon,water quality,swimming performance,predation risk,river ecosystems

There is currently only a limited understanding of the relationship between water quality and predation on Pacific salmon Oncorhynchus spp. smolts.  We addressed the hypothesis that poor water quality will decrease smolt swimming performance and presumably predator-evasion capabilities.  Predation is a major factor affecting salmon smolt survival throughout the San Joaquin River and the Sacramento-San Joaquin Delta of California.  Prior studies have quantified predation rates, but the effect of water quality on predator evasion capability has not previously been evaluated.  We quantified the swimming performance of juvenile Chinook salmon O. tshawytscha in relation to water quality variables.  The maximum swim speeds (Umax) of 45 hatchery-reared smolts (7.1-9.9 cm FL) were measured in controlled (laboratory) and field environments by using a mobile swim tunnel respirometer; measurements were obtained before and after the fish received a 2-d exposure to the lower San Joaquin River while being held in flow-through cages.  To sample across a diversity of environmental conditions, we conducted trials during a 6-week period that coincided with the peak smolt migration.  Regression models were constructed to evaluate relationships between swimming performance and four water quality covariates (water temperature, turbidity, dissolved oxygen, and conductivity).  We found negative relationships between Umax and both temperature and turbidity, and we described these relationships graphically.  Our findings suggest that water quality management strategies with the potential to improve salmon smolt survival include managing temperatures and suspended sediment concentrations to optimize the swimming capacity of migrating smolts and possibly improve their ability to evade predators.

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Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Characterize relationships between habitat and ecosystem processes, climate variation, and the viability of organisms.
Characterize the interaction of human use and habitat distribution, quantity and quality.