Movement and summer habitat of brown trout (Salmo trutta) below a pulsed discharge hydroelectric generating station

Radiotelemetry was used to investigate detailed movement and summer habitat of brown trout Salmo trutta (size range 157-488 mm TL, n = 18) in the Kana naskis River, Alberta. Flows in the Kananaskis River respond to pulsed dail y discharge from an upstream hydroelectric generating facility (range 0.15- 25 m(3) s(-1)). Wetted area available for brown trout doubled during period s of high flow. Fluctuating river levels did not appear to influence the de gree to which brown trout moved within the study site. However, there was e vidence that brown trout used cover and pools more as discharge increased. During high flow conditions, brown trout used similar depths (63 cm), and s ignificantly lower surface water velocities than during low flow conditions . Brown trout also moved closer to shore into interstitial spaces among woo dy debris and root complexes during high flow. Pool habitats were used most often compared with all other habitat types combined. Pools with large woo dy debris accounted for 75% of all habitat observations. Woody debris was u sed more often than all other cover types. Results of the study indicate th at the effects of river regulation on brown trout appear to have been moder ated by woody debris in pools and along river banks, which provided refuge from high water velocities during periods of high flow. Copyright (C) 1999 John Wiley & Sons, Ltd.