Evaluation of Underwater Noise Levels Caused by Ships Movement in the Kakinada Bay Area

With the increase in the number of ship operating in the oceans, shipping traffic is identified as a major contributor to the increase in the ocean noise levels. Shipping radiated noise have led to a longer term and broad scale effects with a concentration of sound generation in coastal areas and along wider shipping lanes. The primary noise sources from the ship are the propulsion system, operational machinery and the flow around the hull. This noise, often unintentional and unwanted, can have significant impacts on marine life, affecting communication, navigation, and behavior of marine species. With the current knowledge being limited in some areas, the issue became a major concern with studies focused on understanding the sources of noise, developing measurement techniques and exploring mitigation measures. In the present paper, efforts were exerted to evaluate the underwater noise levels due to various ship types movement within the Kakinada port waters which is also an important location near to coring wildlife sanctuary. The port facilitates various types of vessel operations including large cargo ships, barges and many fishing boats. The background underwater radiated noise (URN) levels measured were around 120-130 dB re 1µPa in the region. The vessel operation increased the URN by over 20-40 dB re 1µPa higher than the background noise levels. Mitigation means need more assessment of their effectiveness due to vast remaining uncertainties. In addition, a better standardization is required aligned with a more effective governance of the activities producing noise. One way is by increasing awareness of the issue by the decision-makers and implementing the underwater noise management plan to assist the authorities.