Conventional and EMG telemetry studies of upstream migration and tailrace attraction of adult Atlantic salmon at a hydroelectric installation on the Exploits River, Newfoundland, Canada

Conventional and electromyogram (EMG) radio telemetry studies have documented occurrence of tailrace attraction and residency, and associated energy cost, for migratory wild Atlantic at a power plant on the Exploits River, insular Newfoundland, Canada. All fish demonstrated some degree of tailrace attraction and turbine discharge was the primary factor resulting in 'false attraction'. In 2002, residency times were generally less than 1 h, although some fish demonstrated residency between 71 and 118 h. In 2004, after plant refurbishing, fish took from 6 to 11 days to reach the power plant and remained in the tailrace area from 3 to 12 days. Frequent entrances into the tailraces indicated fish were demonstrating a searching behaviour to find the upstream migration route. In 2003 and 2004, EMG data were collected from 3 fish in each year migrating to, and past, the tailraces. An Energy Index was calculated integrating EMG signal and time spent at each location to estimate potential energetic cost. Relatively high-energy expenditure was associated with tailrace attraction and residency in both years. In 2003, fish spent highest energy at the lowest tailrace (first encountered in their migration) while in 2004, there were also high-energy costs associated with a new generating unit. In both years, high EMGs both just below and above the power plant suggested these reaches were arduous and difficult to pass.