Effects of regulated discharge on burbot migration

Abstract

Burbot Lota lota movement and river discharge were studied in the Kootenai River, Idaho, U.S.A. and British Columbia, Canada, downstream of Libby Dam, Montana, U.S.A. A total of 24 adult burbot with transmitters were tracked from 1994 to 2000, for analysis of a travel distance of ≥5 km in ≤10 days termed ‘stepwise movement’. Of 44 ‘stepwise movements’, significantly greater movements during pre‐spawning and spawning were observed when average daily discharges from Libby Dam were <300 m3 s−1, with a mean of 176 m3 s−1, similar to pre‐dam conditions. Burbot travelled at a greater rate during all seasons (3·36 km day−1) at discharges >300 m3 s−1(mean = 1·84 km day−1) than at discharges >300 m3 s−1 but no difference was found for the pre‐spawning and spawning period. Burbot that started ‘stepwise movements’ in low discharge conditions frequently stopped during low discharges.