Effects of Sound Intensity and Frequency on Negative Phonotaxis in Adult Bighead Carp

To provide a theoretical basis for sound barrier technology for fish, the effects of sound intensity and frequency on negative phonotaxis in adult bighead carp, Hypophthalmichthys nobilis, (weight 1.42–2.20 kg, body length 45.1–54.8 cm) were tested using underwater sound equipment in a pool with sound absorbing material to reduce sound reflection. There were two primary findings: (1) The cumulative times that fish remained in the high, medium and low sound intensity areas were significantly different (p < 0.001). The cumulative time decreased as sound intensity increased, demonstrating negative phonotaxis by the test fish towards high sound intensity. The cumulative time that fish remained in the high sound intensity area was less than in the control area and the difference was highly significant (p < 0.001). This strongly negative phonotaxic response can be exploited in developing sound barriers for guiding fish. Negative phonotaxis could be used to guide fish away from hazards and along migration routes, to help prevent exotic fish invasion, and to improve spawning success by preventing migration into tributaries where habitat has been severely impacted by dams or other human activities. (2) Adult H. nobilis respond differently to different frequencies of single-frequency sound. Higher-frequency sound (300–1000 Hz) produced a stronger negative phonotaxic response than lower-frequency sound (50–200 Hz), and the difference in cumulative times was highly significant (p < 0.001). Thus, high-frequency sound is more effective than low-frequency sound for producing negative phonotaxis. This research demonstrates that negative phonotaxis is affected by sound intensity and frequency. However, for a given application and target species, additional research should be carried out to determine the most effective combination of acoustic parameters.