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AB 17:47-56 (2012)  -  DOI:

Swimming activity of migrating Chinook salmon in a regulated river

Caleb T. Hasler1,*, Brent Mossop2, David A. Patterson3, Scott G. Hinch4, Steve J. Cooke

1Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
2BC Hydro, 6911 Southpoint Drive, Burnaby, British Columbia V3N 4X8, Canada
3Fisheries and Oceans Canada, Science Branch, Pacific Region, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
4Centre for Applied Conservation Research, Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada

ABSTRACT: Adult Pacific salmon Oncorhynchus spp. have a fixed amount of energy available to fuel their freshwater spawning migration, so they must optimize their activity in a manner that conserves energy to ensure successful spawning. The flow regime in the Puntledge River in British Columbia, Canada, is regulated for hydropower production, and this has resulted in alterations in discharge and water temperature. The purpose of this study was to assess the relative changes to locomotory activity in Puntledge River summer-run Chinook salmon O. tshawytscha at varying discharges, temperatures, and reaches. Coded electromyogram (EMG) radio transmitters were used to evaluate aerobic swimming-muscle activity of free-swimming fish. Because transmitter calibration was not possible, a standardized EMG (SEMG) value was used to relate relative activity to variability among individuals, reaches, encountered temperatures, and discharge variables. A random forest algorithmic modeling analysis was used to account for the non-independence of predictor variables and activity values repeatedly recorded on the same fish. The model accounted for 57.6% of the variance in SEMG and revealed that individuals accounted for most of the variation in SEMG, followed by reach, temperature, and discharge. These findings indicate that individual variability in swimming strategies, migratory behaviors, and habitat use may influence swimming activity to a greater degree than river conditions. If such findings are confirmed in other regulated systems, this would have important implications for how alterations in flow and their biological consequences are evaluated.

KEY WORDS: Adult Pacific salmon · Upriver migration · Energy use · Electromyogram · EMG ·  Individual variation · Temperature · Discharge

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Cite this article as: Hasler CT, Mossop B, Patterson DA, Hinch SG, Cooke SJ (2012) Swimming activity of migrating Chinook salmon in a regulated river. Aquat Biol 17:47-56.

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