Infrasound produces flight and avoidance responses in Pacific juvenile salmonids

Abstract

A 10‐Hz frequency sound caused flight or avoidance responses in juvenile spring chinook salmon Oncorhynchus tshawytscha and rainbow trout O. mykiss. Groups of fish were placed in 3‐m diameter circular tanks with a water depth of 1 m. The sound source was a 25‐cm diameter aluminium tube with a piston in one end. The piston was driven back and forth by an eccentric coupling to an electric motor at a frequency of 10 Hz and with peak to peak amplitude of 4 cm. The sound source was turned on for 5 s when the fish was within 1 m. Initial tests always resulted in a strong flight response, but after three to four tests the fish more typically simply swam away as far as possible from the source. This avoidance response did not habituate even after 20 trials.