The Radiating Sound Signals of Golden Pomfret Farming in a Large Cage

The radiating sound characteristics of golden pomfret farming in a large cage powered by wave energy and photovoltaic generation are studied. Radiating sound signals in time and spectral domain of fish in the cage are measured during 24 hours. The testing contents include: the fish are in a quiet free-swimming state, the fish are excited by outside interference of a large ship, and are stimulated by feeding. The conclusions are as follows: the external disturbance caused by the power equipment and small fishing boats have no obvious effect on the vocalization of fish; When the golden pomfret are in the state of quiet and free-swimming late at night or early in the morning, they do not eat and send the sounds weakly or even keep silence, and average SPL(sound pressure level) of the ocean background is about 70dB. During the feeding process, the fish produce knocking and chewing sounds with frequency band ranged from 300-1100Hz, and the center frequency is 670Hz. The highest SPL in the spectrum is about 88dB. When the fish are disturbed by an passing large ship and feeding activities occur at the same time, the highest SPL is about 103dB with the central frequency of 630Hz. The radiating sound of the fish is superimposed with the interference signal of 100-2400Hz. The results show that under strong background noise, the sound production of fish can be measured by passive sonar. The studies are helpful for mastering time and frequency characteristics of the radiating sound by fish in the large cage. The main purpose of this study is to provide a reference for analysis and evaluation of the correlation between the biological behavior and acoustic ecology of the ocean.