Noise impact assessment on Indo-Pacific Humpback Dolphin in the habitat of the East Taiwan Strait during the first two pile driving activities of demonstration offshore wind farm

Abstract

Foundation piles of the first two wind turbines were driven off the coast of Miaoli, Taiwan in 2016. However, that area is also the habitat of the critically endangered Eastern Taiwan Strait (ETS) population of Indo-Pacific humpback dolphin (Sousa chinensis). To assess potential noise effects from pile driving on the humpback dolphins, we collected underwater noise data during the construction and found that the sound pressure level (Lrms) at 750m was less than 180dB re 1μPa and the peak sound pressure (Lpk, flat) was less than 190 dB re 1μPa. We also presented recommendations of noise and marine mammal monitoring for future pile driving activities. It includes an exclusion zone of radius 750m from the piling location and the peak sound pressure (Lpk, flat) not to exceed 190~220 dB re 1μPa at 750 m distance, and an observation zone extends to 1500m radius where both marine mammal observers and passive acoustic monitoring are posted. [This work was sponsored by Ministry of Science and Technology of Taiwan (105-3113-E-002 -002 -CC2), Taiwan Bureau of Energy and Industrial technology Research Institution (05HZT56002), and U.S. Marine Mammal Commission’s Research and Conservation Grant.]