Relative activity of brook trout and walleyes in response to flow in a regulated river
activity, trout, walleye, telemetry, habitat, flow regimes, strategy, ecology
Journal or Book Title
North American Journal of Fisheries Management
Coded electromyogram telemetry transmitters were used to examine the effects ofvarying flows on the relative activity of brook trout (Salvelinus fontinalis) and walleye (Sandervitreus) in a regulated river. The relative activity levels of two brook trout and two walleyes werecontinuously monitored for a minimum of 24 h, and measurements were compared with river flowvalyes logged at nearby gauging stations. Generally, fish relative activity levels mimicked patternsof flow change, peaks in activity level corresponding to peaks in flow. Mean relative activity wasgenerally greatest at extreme high (> or = 25 m3/s) and low < 15 m3/s) flows. High flows mayhave elicited hyperactivity (increased activity) as fish sought suitable refugia, increased activity tohold position in the water column, or increased feeding activity on increased levels of driftinginvertebrates. Hyperactivity at low flows may have been caused by relocation due to habitat lossor ease of movement at lower flow regimes. Physiological telemetry provides researchers with amethod of quantifying the immediate effects of flow changes on fish. Increasing our knowledge ofthe effects of river regulation on fish is essential to the development of more effectivemanagement strategies that balance ecology and economics.