Behavior responses of Blackhead seabream (Acanthopagrus schlegelii) to underwater noise

Underwater noise levels are increasing due to anthropogenic activities, especially in the densely populated coastal area and open ocean. Many studies have been evaluating the effect of anthropogenic noise on marine fish. However, the more information is needed to predict any negative effects. The startle behavior responses of the Blackhead seabream (Acanthopagrus schlegelii) were researched in this paper. The Blackhead seabream held in a rectangular tank, were exposed to a sweep sound of 100-1000 Hz, at root mean square sound pressure levels (SPLrms) starting from 120 dB to 180 dB re1μPa. Two kinds of duration (1-s and 20-s) sweep sounds were used in the test. The behavior responses of the fish were occurred at 136 dB of SPLrms(in both duration), which firstly implicated the auditory threshold of the Blackhead seabream. Under the 1-s sweep sound, the responses of fish were stronger than the 20-s sound. Certain motion parameters, such as swimming speed, the individual number of stay around the sound source and the occurrence number of direction changed, were statistical analyzed. When exposed to the SPLrmsat 136 dB, the average speed of fish was varied significantly (P <;0.05), compared to the data of normal state. With the increased of sound pressure level, the fish showed significant avoidance of the sound source and move faster speed than the original.