Rainbow Trout and Brook Trout Mortality from High Voltage AC Electrofishing in a Controlled Environment

Twelve groups of 250 hatchery rainbow trout (Salmo gairdneri) and brook trout (Salvelinus fontinalis) were electroshocked in hatchery raceways and monitored for 15 days. The mean immediate, delayed, and total mortality was less than 2% at all alternating current voltages tested (350, 700, and 760 volts). Radiographs of surviving trout showed that only a small percentage (<3%) had dislocated or fractured vertebrae. Excessive delayed mortality from the use of high-voltage alternating current to sample trout populations in waters with low conductivity should be of little concern for most management activities.