Survival of juvenile rainbow trout passing through a Francis turbine

The immediate survival rate of juvenile rainbow trout Oncorhynchus mykiss (fork length, 81 +/- 1 mm) that passed through a Francis turbine at Hb Dam on the Hinemaiaia River in the central North Island of New Zealand was estimated at 95.6 +/- 1.1% (mean +/- SE). The survival rate decreased to 93.1 +/- 1.4% after 24 It and remained unchanged after 96 h. The survival rate was derived using maximum likelihood estimators for a tag-recapture model involving three releases of 200 fish of similar average length, and the mortality due to handling was estimated using a control of 200 similarly sized fish. The high survival of juvenile rainbow trout (< 80 mm) passing through the Francis turbine at Hb power station provides a safe route for fish migrating downstream from Hb Lake into the Hinemaiaia River and Lake Taupo.