Humboldt-Universität zu Berlin - Albrecht Daniel Thaer-Institut für Agrar- und Gartenbauwissenschaften

Abstract: The trade-off between remaining stationary and being active has consequences for the survival and growth of fishes. Recent advancements in telemetry tools have enabled researchers to assess activity patterns of free-swimming fishes using tri-axial accelerationsensing acoustic transmitters. This study describes the summer activity patterns of muskellunge (Esox masquinongy) in an 8 km reach of the Rideau River, Ontario between 1 June and 20 August 2010. Acceleration measurements indicated that muskellunge tended to remain inactive for much of the time. The effect of time of day (i.e., diel patterns), water temperature, and fish size were also examined. Activity was lowest at dawn, increased throughout the day, peaked at dusk, and declined at night. Activity also declined above temperatures of 25 °C and was lower for larger muskellunge. A comparison of fish captured with rod and reel versus boat electrofisher failed to reveal a significant difference in behaviour. The results of this study illustrate the utility of accelerometer transmitters for studying the behavioural ecology of free-swimming fishes. The results also confirm that muskellunge are generally sedentary during the summer period, but do exhibit reasonably pronounced diel activity patterns