Underwater noise
Criteria by type of participant
Ship owners
Ports
SHIP OWNERS
Performance indicator's objective:
Reduce underwater noise made by ship operations to reduce impacts to marine mammals.
Notes:
- Green Marine Europe recognizes that underwater noise may potentially impact a broader range of aquatic species other than just marine mammals. While the initial objective of this indicator covers marine mammals, future development of this Performance Indicator may expand its scope.
- Green Marine Europe recognizes that for most ships, under most operational conditions, cavitation is the main source of underwater noise.
- Applicable only for vessels transiting in salt water.
2025 Criteria
Level 1
Monitoring of regulations
Level 2
2.1. Conduct regular hull cleaning and propeller blade maintenance. The participant must keep a record of these actions for each vessel in their fleet.
Note: Hull cleaning and propeller maintenance should at least be done during dry dock.
2.2. Review the list of sensitive areas in Canadian, US and EU waters to determine whether the participant’s vessels transit through or have operations in such areas. Ensure that this information is communicated to each vessel.
Note: See Annex 6-A.
2.3 Participate in voluntary traffic measures, if such measure provides noise-reduction benefits, such as a slowdown, alternative routing or lateral displacement or any equivalent measure(s), in specific zones as identified by a port or governmental authority.
Note: The Particularly Sensitive Sea Area (PSSA) in the North-West Mediterranean will limit the speed at 13 knots.
Level 3
3.1. Actively participate in providing whale sighting data in European waters through a logbook, a recognized application such as a European version of the US app Whale Alert or the REPCET system (outside mandatory zones for French ship owners), or any other whale sighting research project.
Note: If sightings are recorded in a logbook, the data should be shared with a recognized central database, and reported to a coastal authority, with both done when available.
3.2. Develop and adopt a Marine Mammal Management plan (MMMP) in order to reduce the potential adverse effects of vessels, especially within known sensitive marine areas, as identified in Criterion 2.2.
Note: See Annex 6-B.
3.3 Study what is/are the fleet’s most relevant vessel(s) in terms of underwater noise emissions by working with ports, engineering societies, classification societies or scientific research projects to estimate noise emissions. A ranking could be made across the entire fleet.
Note: e.g., “relevant” could mean:
- Oldest vessel(s) as far as their life duration is sufficient to implement quieting technology
- A series of sisterships
- Vessel(s) having the longest transit time in areas important for marine mammals
- Vessel(s) planning to undertake a drydock or technical stop within 2/3 years
- Vessel(s) whose retrofitting of URN device(s) is/are the most feasible
It is up to the ship owner to justify why the selected vessel(s) would be the most relevant for this study.
Level 4
4.1 Incorporate applicable vessel quieting technologies during retrofits and new vessel construction, including for the vessel(s) identified in 3.3, by increasing propeller diameter and/or number of blades, optimizing wake and inflow, reducing excitation into the steel structure, etc.
Note: Refer to published documents like the IMO and the SNAME MVEP Guidelines, available in the Members section of the Green Marine website. This criterion is applicable only for ship owners ordering/designing new vessels (keel laid after Jan 2018) or conducting retrofits of propulsion systems or other equipment that contributes significantly to underwater noise.
4.2 Support/collaborate on scientific research on underwater noise leading to the estimation of relative ship noise levels for at least one vessel in the company's fleet.
Note: Collaboration with a (bio)acoustician is essential to obtain reliable data. The estimation(s) of relative ship noise can be determined as per IMO 2014 guidelines or a classification society’s referential.
4.3 Train the bridge crew members on board with an expertise certification on marine mammals to avoid cetaceans.
Note: This certification can be a recognized Marine Mammal Observer training or a customized in-house training developed with a relevant expert.
If there are no trained crew members on board, then an observer must be on board instead.
Further requirement applying only to commercial or service vessels in transit time sailing faster than 10 knots and not using full wind propulsion:
Fulfill one of the following 3 criteria:
4.4 If it has acoustic benefits, demonstrate that at least one vessel within the company’s fleet voluntarily and systematically implements at least a 10% speed reduction compared to BAU, in at least one (as defined in the MMMP) Cetacean Critical Habitat, or any other area identified by port or governmental authorities, and demonstrate no increase of usual speed during the rest of the voyage.
Note: AIS data, bridge logbook, or equivalent type of proof could be used for the demonstration.
Note: BAU is the average commercial speed of the year (n-x) before ship owners apply for Level 4.
For vessels equipped with a controllable pitch propeller (CPP), the ship owner must prove with documentation that the speed reduction or other engine/propeller setting point is the best setting for noise reduction impact.
OR
4.5 Obtain a quiet class notation for at least one vessel within the company’s fleet.
OR
4.6 For at least one vessel within the company’s fleet, implement at least two noise reduction technologies in two distinct categories as listed below:
- Propeller noise
- Wake flow modification
- Supplementary treatment and air lubrification system (ALS)
- Machinery treatment
- Other mitigation technology
Note: Refer to Annex 6C for the details within each category and related noise reduction technologies.
Level 5
5.1 Support/collaborate on scientific research on underwater noise allowing the estimation of relative ship noise levels for at least 3 vessels or 15% of the fleet.
Note: Collaboration with a (bio)acoustician is typically essential to obtain reliable data. IMO guidelines could be used as well.
Further requirement applying only to commercial or service vessels in transit time sailing faster than 10 knots and not using full wind propulsion:
Fulfill one of the following 3 criteria:
5.2 If it has acoustic benefits, demonstrate that 15% of the fleet’s vessels (representing at least 10% of the gross tonnage, with a minimum of 3 vessels) voluntarily and systematically implement at least a 10% speed reduction compared to BAU, in at least one Important Marine Mammal Area, Candidate Important Marine Mammal Area (as defined in the MMMP), Cetacean Critical Habitat, or any other area identified by port or governmental authorities; and, demonstrate no increase of usual speed during the rest of the voyage.
Note: AIS data, bridge logbook, or equivalent type of proof could be used for the demonstration.
Note: BAU is the average commercial speed of the year (n-x) before ship owners apply for Level 5.
For vessels equipped with CPP, the ship owner must prove with documentation that the speed reduction or other engine/propeller setting point is the best setting for noise reduction impact.
OR
5.3 Obtain a quiet class notation for 15% of the fleet’s vessels (representing at least 10% of the gross tonnage, with a minimum of 3 vessels).
OR
5.4 For at least 15% of the fleet’s vessels (representing at least 10% of the gross tonnage, with a minimum of 3 vessels), implement at least two noise reduction technologies in two distinct categories as listed below:
- Propeller noise
- Wake flow modification
- Supplementary treatment and air lubrification system (ALS)
- Machinery treatment
- Other mitigation technology
Note: Refer to Annex 6C for details within each category and related noise reduction technologies
PORTS
Performance indicator's objective:
Manage and mitigate underwater noise (UN) sources from ships entering and exiting the port and from regular port activities and operations, maintenance, development, and construction work to reduce impacts on marine species, particularly marine mammals.
APPLICABILITY: Applicable only for ports located in marine (saltwater) environments, including brackish waters such as estuaries.
NOTE:
- Growing evidence shows that UN can adversely impact a broad range of aquatic species like fish, benthic invertebrates, reptiles like sea turtles, etc. Based on its level and frequency, UN can have direct or indirect as well as physiological, auditory, and behavioural effects on exposed species, depending on their sensitivity to noise. Given the current level of knowledge and extent of existing practical approaches to reducing UN impacts on marine mammals, ports can focus their efforts on protecting these species by applying the criteria of this performance indicator. However, they are also encouraged to consider other marine species impacted by UN. Future development may expand the scope of the indicator to include freshwater species and ports in freshwater environments.
- This indicator references the document listed below that can be found on the Members’ Section of Green Marine Europe’s website:
- International Maritime Organization (IMO) Revised guidelines for the reduction of underwater radiated noise from shipping to address adverse impacts on marine life (MEPC.1/Circ.906) (criteria 2.1, 4.3 – See Annex 1 for examples of class notations).
2025 Criteria
Level 1
Monitoring of regulations
Level 2
Fulfill 3 of the 4 following criteria:
2.1 Promote and raise awareness of tenants and ship operators calling at the port about the issue of UN and approaches to managing it by distributing the International Maritime Organization (IMO) revised guidelines, along with any other pertinent information on the effects of UN on marine species and sensitive areas.
2.2 Promote the provision of marine mammal sighting data by port users, including ship owners and pilotage associations, using a recognized application (e.g., Whale Alert, Whale Report, and the Pelagis Observatory) or a logbook reported to a recognized central database or subject regulator.
2.3 Summarize current knowledge on sensitive habitats and marine species potentially impacted by UN in the area (e.g., using the World Shipping Council Whale Chart) to better understand the extent of the port’s zone of influence on the local soundscape (e.g., operations/ maintenance/construction/development zones, shipping traffic routes, anchorage sites), which may inform vessel traffic management (e.g., slowdown zones, alternative vessel routing).
2.4 Contract a competent and/or experienced marine mammal or protected species observer (MMO or PSO, respectively) during port-related in-water or on-land construction work (below high-water mark) that is known to increase significantly the level of noise in the soundscape, and prioritize daylight periods for noisier work.
Note: Applicable for ports or port tenants engaged in construction or development work. The decision to require the services of a MMO or PSO should be based on the presence of endangered species and sensitive areas.
Level 3
3.1 Implement all applicable criteria listed at Level 2.
3.2 Develop and adopt an Underwater Noise Mitigation and Management Plan (UNMMP), which incorporates a range of noise mitigation options, best practices, and operating procedures for both impulsive and ambient noise-generating activities including port maintenance, construction, and development, shipping traffic, and/or anchorage sites.
Note: See Annex 6-A.
AND fulfill one of the following 3 criteria:
3.3 As part of the UNMMP, establish an ambient UN monitoring program and, to understand local soundscape conditions, analyze and archive the UN data.
Note: The program must be developed in collaboration with a bioacoustician or a specialized firm and specify the objectives, methodology, location of hydrophones, and data collection frequency. If the port is planning time-limited construction, development, or operational changes, additional noise measurements should be taken using the same protocol to see how those activities change the soundscape conditions.
OR
3.4 Offer a recognition program to ship owners who demonstrate efforts to reduce ship underwater radiated noise.
Note: Efforts may include evidence of operational measures, such as hull and propeller maintenance, and participation in speed reduction programs and alternative routing measures.
OR
3.5 Participate in a regional stakeholder group with industry members (e.g., port tenants, other ports in the region, ship owners, shipyards) or an expert working group to advise and facilitate research and development, projects, or programs.
Level 4
4.1 Implement all criteria listed at Level 3.
4.2 Develop and incorporate UN reduction targets into the UNMMP in the port’s jurisdiction and/or surrounding waters based on data obtained from the ambient UN monitoring program in criterion 3.3.
Note: This strategy must include a methodology to measure progress achieved in reducing UN generated at the port and to set realistic noise reduction targets.
AND fulfill one of the following 4 criteria:
4.3 Administer an incentive program for ship owners implementing vessel noise mitigation measures (e.g., offer a discount/berthing fee reduction for ships with a class notation for UN).
OR
4.4 Establish an in-situ acoustic monitoring system with a detailed protocol to collect data on the relative source level of individual ships or on the noise level as contributed by vessel type, and share this data with ship owners.
Note: This criterion is linked with criterion 4.2 from the Underwater Noise indicator for ship owners.
OR
4.5 Within the last five years, support/collaborate on scientific research that includes the measurement of UN from ships and/or other port-related activities.
OR
4.6 Lead or co-lead a permanent regional or local stakeholder group with industry members (e.g., port tenants, other ports in the region, ship owners, shipyards) as well as research and environmental groups and governmental agencies, aiming to share UN-related information, raise awareness, and identify mitigation and management measures relevant at the regional level along shipping routes and in port areas. The group must meet minimally twice a year.
Level 5
5.1 Implement 4 of the 6 criteria listed at Level 4.
5.2 Demonstrate that the UN reduction targets set in criterion 4.2 are met through direct measurement.
Note: If a significant correlation is demonstrated between a proxy variable (e.g., participation rate in a vessel slowdown) and UN reduction, and if approved by Green Marine Europe, the proxy measurement may be used in alternation with direct measurements to demonstrate that targets are on track.
5.3 Demonstrate continual improvement in implementing the UNMMP through the use of noise reduction solutions and technologies that reduce UN.
