Energetic Consequences of Stranding of Juvenile Atlantic Salmon (Salmo salar L.)

An effect of hydropower and hydropeaking regulation in rivers is stranding of fish. Those fishes that survive stranding may experience stranding as a stressful situation. In four experimental stranding experiments (each with 6 individuals in 10 control and 10 treatment replicates), the energetic consequences of two forms of stranding (i.e. trapping and beaching) of juvenile Atlantic salmon (Salmo salar) were investigated in summer and winter. Restricted food access in the experimental channels ensured that effects of hydropeaking could be revealed. Mean fish length ranged between 60 mm and 110 mm among experiments. Both during the winter and summer experiments fish did not grow in length, neither in the control nor in the treatment channels and fish lost body mass as well as body fat in all experiments (body fat in summer trapping experiment not determined). The four experiments revealed similar results: stranding did not affect growth or energy content. Despite the severity of the stranding and the resulting mortality, which was especially high during summer, no stranding related effects on fish performance could be detected.