Ship noise-induced temporary hearing threshold shift in the Chinese sucker Myxocyprinus asiaticus (Bleeker, 1864)

The study objective was to explore the effects of noise generated by a 2000 hp containership on the reaction of Chinese sucker Myxocyprinus asiaticus. The noise was played back for various durations (1, 2, 4, 8, 24h) at 142.8dB re 1Pa. Immediately after the noise exposure, hearing abilities of the fish were tested using the auditory evoked potential (AEP) protocol and compared with the response to a control group with no noise exposure. After 1h noise exposure no significant differences were found compared to control fish; however, significant auditory threshold shifts began to occur at 800Hz after 2h of noise exposure. After 24h of noise exposure, significant auditory threshold shifts were found at all tested frequencies (100-3000 Hz) when compared to control fish. Recoveries were also measured until the auditory thresholds returned to the hearing levels of the control fish. Auditory thresholds of all Chinese suckers fully returned to control levels within 96h of recovery time. The results indicate that ship noise exposure can lead to threshold shifts in Chinese sucker and that these threshold shifts are temporary, referred to as temporary threshold shift (TTS).