Reactions of cyprinids to infrasound in a lake and at the cooling water inlet of a nuclear power plant

Behavioural effects of infrasound on cyprinids were tested. In Lake Borrevann, Norway, acute avoidance responses, at a distance up to 10 m from a 16 Hz infrasound projector were revealed by echosounding. At 10 m distance, a coarse estimate of the stimulus level (measured as the acceleration component of the particle motions) was c. 10 −3 m s −2 . Habituation was not evident during these tests. Two synchronized infrasound units were also installed 6 m apart in front of a cooling water intake of a nuclear power plant on the River Meuse, Belgium. Echosounding was used to compare the number of fishes entering the intake canal during on–off infrasound sequences. Relative to off‐periods, the reduction of the number of fishes entering during on‐periods was >80% at a distance of 0–12 m from the units. A significant reduction of 48% was observed considering the whole width (54 m) that was monitored. Fish impingement on the mechanical screens during the study revealed that >90% of the fishes entering the intake were cyprinids.