Ship noise can have negative impacts – on both humans and marine life.
Noise on ships
Continuous noise onboard ships can have an adverse impact on human health. IMO adopted, in 2012, a regulation in the International Convention for the Safety of Life at Sea (SOLAS) to require ships to be constructed to reduce on-board noise and to protect personnel from noise, in accordance with the Code on noise levels on board ships. The Code sets out mandatory maximum noise level limits for machinery spaces, control rooms, workshops, accommodation and other spaces on board ships.
The International Labour Organization’s Maritime Labour Convention (MLC 2006) also has requirements with respect to preventing the risk of exposure to hazardous levels of noise on board ships.
Underwater noise and impact on marine mammals
Studies have shown that underwater-radiated noise from commercial ships may have both short and long-term negative consequences on marine life, especially marine mammals. The issue of underwater noise and impact on marine mammals was first raised at IMO in 2004. It was noted that continuous anthropogenic noise in the ocean was primarily generated by shipping. Since ships routinely cross international boundaries, management of such noise required a coordinated international response.
Guidance on reducing underwater noise
In 2014, IMO's Marine Environment Protection Committee (MEPC) approved guidelines on reducing underwater noise from commercial shipping, to address adverse impacts on marine life. Given the complexities associated with ship design and construction, the Guidelines focus on primary sources of underwater noise, namely on propellers, hull form, on-board machinery, and various operational and maintenance recommendations such as hull cleaning.
Review of the guidelines
Following instruction from the MEPC in 2021, the IMO Sub-Committee on Ship Design and Construction (SDC) in January 2023 agreed the revised guidelines, for submission to the Marine Environment Protection Committee (MEPC 80) in July 2023.
The draft guidelines recognize that commercial shipping is one of the main contributors to underwater radiated noise (URN) which has adverse effects on critical life functions for a wide range of marine life, including marine mammals, fish and invertebrate species, upon which many coastal Indigenous communities depend for their food, livelihoods and cultures. The draft revised guidelines provide an overview of approaches applicable to designers, shipbuilders and ship operators to reduce the underwater radiated noise of any given ship. They are intended to assist relevant stakeholders in establishing mechanisms and programmes through which noise reduction efforts can be realized.
The draft guidelines include updated technical knowledge, including reference to international measurement standards, recommendations and classification society rules. They also provide sample templates to assist shipowners with the development of an underwater radiated noise management plan.
The draft guidelines will now be submitted to the Marine Environment Protection Committee (MEPC 80), which meets from 3-7 July 2023, for approval.
The draft guidelines were developed by a correspondence group with further work completed by a working group which met during the Sub-Committee session.
The correspondence group was re-established, to report back to SDC 10 in January 2024, to address the remaining work under the agenda item. It was, in particular, tasked with revising a flowchart on the URN Noise Management Planning process to reflect the Revised Guidelines, and the underwater noise management plan included in appendix 3, to be used as a tool for raising awareness. The group will also finalize and prioritize the provisional list of suggested next steps to further prevent and reduce underwater radiated noise from ships.
The Sub-Committee agreed a work plan which envisages, among other things, identifying ways to implement the Revised Guidelines and increase awareness and uptake; organizing an expert workshop on potential co-benefits and trade-offs that may exist between the reduction of underwater radiated noise from ships and energy efficiency; and developing a plan of action for further work.
Global Partnership for Mitigation of Underwater Noise from Shipping
IMO is currently designing a new project, the GloNoise Partnership project, which aims to address the issue of underwater noise from shipping. The project is currently in a preparatory phase and is expected to launch in mid-2023, subject to approval and funding by the United Nations Development Programme (UNDP) and the Global Environment Facility (GEF). If approved, the project is expected to receive $2 million in funding under the GEF International Waters focal area, and will be executed by IMO over a period of two years.
The GloNoise Partnership will focus on building capacity in developing countries to implement the Guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life.
Particularly Sensitive Sea areas and routeing measures
The issue of underwater noise and its effects on marine life is also taken into account through IMO adopted “Particularly Sensitive Sea Areas” (PSSAs). These are areas considered to deserve special protection, due to their recognized ecological or socio-economic or scientific significance, and which may be vulnerable to damage by ships. Ship routeing measures can be proposed for adoption in connection with a PSSA, to protect marine life.
IMO has also adopted a series of routeing measures to protect whales and other cetaceans from ship strikes during breeding seasons, by keeping ships away from specified areas. So these measures may also have a positive effect in terms of reducing the impacts of underwater noise. (Click for the article: Routing for Whales.)
Noise from dredging
Noise has also been discussed in the context of the work of the London Convention and Protocol on the protection of the marine environment from pollution from dumping of wastes and other matter. Dredging activities – dredged material is the main source of permitted wastes dumped at sea under these treaties - are also a source of anthropogenic noise.
The World Dredging Association (WODA) has submitted technical guidance on underwater sound in relation to dredging activities to the London Convention and Protocol Scientific Groups, providing advice to decision-makers, stakeholders and scientists on how to manage impacts of underwater sound, primarily from dredging.
Ship underwater radiated noise technical report and matrix (MEPC 74/INF.28 - Canada)
- Download the 2014 IMO Guidelines on reducing underwater noise from commercial shipping (these will be updated in 2023).
- Submission on IMO's work on anthropogenic underwater noise to the 2018 nineteenth meeting of the United Nations Open-Ended Informal Consultative Process on Oceans and the Law of the Sea, on "Anthropogenic underwater noise" (18-22 June 2018).
- Expert Workshop on Underwater Noise and its Impacts on Marine and Coastal Biodiversity (2014) – report and submissions can be downloaded here.
- Understanding Anthropogenic Underwater Noise (Canada) - https://www.tc.gc.ca/eng/anthropogenic-underwater-noise.html
- Listen to whale sounds and whale calls being masked by the sound of a large ship passing by a pod on the Port of Vancouver website.
- Ocean noise page (NOAA) - https://oceanservice.noaa.gov/facts/ocean-noise.html
- Underwater sound in relation to dredging (Central Dredging Association (CEDA))
IMO and the Oceans: IMO’s work to address noise from commercial shipping and its adverse impact on marine life is relevant to the UN Sustainable Development Goal (SDG) 14 on the oceans.