Preliminary exploration of underwater noise impact on Japanese eel (Anguilla japonica) elvers

With the rapid increase in the construction of offshore wind farms and other coastal engineering projects, people begin to realize that anthropogenic underwater noise such as pile driving and underwater explosions can have an adverse impact on marine life. The Japanese eel (Anguilla japonica) is an important economic fish species in China, Japan and South Korea due to its high-quality meat. As most Japanese eel elvers for aquaculture are caught in estuaries or seashores, eel farms are often located close to these locations. Therefore, various underwater noises from coastal constructions and ship traffic may influence local eel aquaculture. In this paper, we observed the behaviour of Japanese eel elvers - with body-length from 8 to 10 cm - under exposure to a controllable underwater noise, and we studied the single frequency and noise impact on Japanese eel elvers. Results showed that the Japanese eel elvers were sensitive to the noise of 600-800 Hz, and particularly to 700 Hz. With the increase of noise pressure level, elvers showed significant avoidance with respect to the sound source, and also that they move at a faster speed than originally.