Environmentalists Push for New Measures to Tackle Underwater Noise

Propeller cavitation
Propeller cavitation is one of the leading sources of underwater noise (SNL.no / CC BY SA 4.0)

Published Jan 29, 2023 10:23 PM by The Maritime Executive

Environmentalists are pushing for tough measures to address the impact of underwater noise from ships on marine life, a problem that is on the rise - particularly in the Arctic.

With studies confirming that underwater noise from shipping is on the rise and continues to roughly double each decade, a group of 20 not-for-profit organizations under the auspice of the Clean Arctic Alliance are pushing for stringent measures to tackle the problem of underwater noise from ships on Arctic wildlife.

The renewed push for tackling underwater noise - which mainly emanates from the propellers and engines of ships - puts more pressure on the maritime industry to develop technologies to mitigate the problem. 

The environmental and conservation organizations want the International Maritime Organization’s (IMO) Sub-Committee on Ship Design and Construction (SDC) that is meeting in London this week to develop compulsory measures that will force shipping companies to reduce underwater pollution that is having adverse impacts on the health of marine wildlife including whales, dolphins and fish.

The organizations believe that the voluntary nature of the IMO’s underwater noise guidelines is the biggest barrier to their implementation. In effect, the UN body must come up with a program of action and identify next steps, including recommendations for compulsory measures during this week’s meeting.

Although in 2014 the IMO developed Guidelines on the Reduction of Underwater Noise from Shipping, the NGOs argue that the last eight years have shown that the voluntary guidelines fail to effectively mitigate the problem.

“The non-binding nature of the current guidelines, which have not been updated since 2014, appears to have led to a de-prioritization of the need for action by the shipping sector – and this is resulting in increasing noise levels in the ocean, including the Arctic – where underwater noise from increased shipping is having a much greater impact,” said Dr Sian Prior, Clean Arctic Alliance Lead Advisor.

The organization stresses that the IMO must agree to the development of mandatory measures such as the preparation and implementation of noise management plans and requiring ships to achieve quantitative underwater noise targets.

“In addition to global measures, even more stringent regional measures to reduce acoustic pollution from vessels in areas such as the Arctic will be necessary,” said Sarah Bobbe, Ocean Conservancy Arctic Program Manager.

For many marine organisms, sound is the most important means of communication. Because vision is very restricted under water, basic functions such as navigating, finding prey and partners can be hampered without good hearing ability. This is of particular importance for marine mammals.

The push for tough measures to tackle shipping's underwater noise pollution follows shortly after a  new study published in ScienceDirect, which found that that underwater noise from shipping continues to roughly double each decade. The Arctic and the Norwegian Sea are the worst affected areas.

The study shows that the largest contributors are containerships, bulkers and tankers, which emit 75 percent of the noise. The findings show that in the list of top 100 noisiest vessels, containerships occupy the first 50 places and represent 80 percent of the entries. 

The increased noise emissions from containerships may be partly because of the increased number of vessels or their increased average size, although noise also depends on operating speed. For bulk carriers, gas tankers and vehicle carriers, the research shows that over 90 percent operate with speeds above their estimated cavitation inception speed, which leads to large underwater noise emissions.

The lack of tangible IMO-led measures has seen some countries move towards regulating underwater noise in their waters, a route that risks leading to differing sets of regulations throughout the ocean - thus creating a lack of clarity and certainty for the shipping industry.