Modeling of Low-frequency Source Levels from Fishing Vessels Using an Acoustic Observatory in the East China Sea

For the past few decades, there has been a focus on the ocean ambient noise in research, one of which is the effect of human-generated noise on marine mammals. The shipping noise has been considered as the main contributor, especially in coastal areas. Less concern has been paid to the research on the underwater radiated noise (URN) from fishing vessels at frequencies below 100 Hz. In the present work, the URN from six fishing vessels measured with an opportunistic bottommounted acoustic observatory in the East China Sea was chosen for the analysis. Inspired by the methodology of RANDI-3, a modified URN model to predict the spectral source levels (SSLs) of fishing vessels at third-octave frequencies below 100 Hz was proposed, in which the corresponding SSL could be expressed as a function of frequency and ship length. Finally, we applied this modified model to estimate the SSL of a reference fishing vessel. The results show that this modified URN model has certain credibility for six fishing vessels as well as other fishing vessels within certain limits.