Effects of Short-Term Flow Fluctuations on Displacement of, and Habitat Use by, Brown Trout in a Small Stream

Induced peaking flows that increased discharge 4–100 times (up to 350 L·s–1) in a small stream did not displace brown trout Salmo trutta (mean total length ≥ 67 mm) downstream. Coarse substrate was thought to be essential by creating low-water-velocity microniches. In the available habitat, brown trout were significantly associated with certain depths, water velocities, substrate, and cover. Larger fish occupied areas with deeper water and more cover than did yearling brown trout. Short-term changes in flow did not influence habitat use. Fluctuating flows increased emigration slightly, especially at night.