title: Burst swimming in areas of high flow: delayed consequences of anaerobiosis in wild adult sockeye salmon.
abstract: Wild riverine fishes are known to rely on burst swimming to traverse hydraulically challenging reaches, and yet there has been little investigation as to whether swimming anaerobically in areas of high flow can lead to delayed mortality. Using acoustic accelerometer transmitters, we estimated the anaerobic activity of anadromous adult sockeye salmon (Oncorhynchus nerka) in the tailrace of a diversion dam in British Columbia, Canada, and its effects on the remaining 50 km of their freshwater spawning migration. Consistent with our hypothesis, migrants that elicited burst swimming behaviors in high flows were more likely to succumb to mortality following dam passage. Females swam with more anaerobic effort compared to males, providing a mechanism for the female-biased migration mortality observed in this watershed. Alterations to dam operations prevented the release of hypolimnetic water from an upstream lake, exposing some migrants to supraoptimal, near-lethal water temperatures (i.e., 24°C) that inhibited their ability to locate, enter, and ascend a vertical-slot fishway. Findings from this study have shown delayed post-dam passage survival consequences of high-flow-induced burst swimming in sockeye salmon. We highlight the need for studies to investigate whether dams can impose other carryover effects on wild aquatic animals.
authors.affiliation: Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, Ottawa, Ontario K1S 5B6, Canada; 2Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada; 3InStream Fisheries Research, Vancouver, British Columbia V5M 4V8, Canada.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Burnett
authors.forename: Scott G
authors.initials: SG
authors.lastname: Hinch
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Braun
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Casselman
authors.forename: Collin T
authors.initials: CT
authors.lastname: Middleton
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Wilson
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Cooke
mesh_terms: D061725:Accelerometry / Q000662:veterinary; D000693:Anaerobiosis; D025041:Animal Migration; D000818:Animals; D001955:British Columbia; D005260:Female; D060106:Lakes; D008297:Male; D045483:Rivers; D012474:Salmon / Q000502:physiology*; D013550:Swimming; D014872:Water Movements