Passive Acoustic Observations in the Shallow Waters of Northwest Bay of Bengal to Study the Effects of Impact Pile Driving on Fish Chorus

摘要

Ambient noise time series measurements were recorded in the shallow water of Northwest Bay of Bengal. A few data sets revealed the presence of impact pile-driving noise. The site is also known for the presence of the species Terapon theraps (Family:Terapontidae), and the fish chorus was recorded during the measurement period. Sound metrics of impact pile-driving noise were calculated to assess their potential impacts on fish chorus. Averaged peak sound pressure level reached 162 dB re 1 mu Pa, and single-strike sound exposure level is about 134 dB re 1 mu Pa-2 s, leading to a cumulative sound exposure level of approximately 148 dB re 1 mu Pa-2 s. The impact pile-driving signal has the highest energy in lower frequency band over 0.05-1 kHz. It is observed that T. theraps fish chorus also displays their pulse repetition rate and swimbladder spectral peaks at lower frequencies. Detailed analysis of the entire data sets indicates that the fishes were exposed to the pile-driving noise, which would have an impact on the chorus made by them.