Underwater noise

Shipping is one of the main sources of continuous underwater noise, which adversely affects the vital functions of a wide range of marine life, including marine mammals, fish and invertebrate species. Continuous underwater noise can, for example, restrict the communication of marine mammals and drive them out of their habitat. Sound is the primary sensory mechanism used by aquatic organisms for social interaction, reproduction, navigation and the detection of obstacles, prey, predators and other threats. The main sources of noise from vessels overlap with the hearing range and use of sound of different species. Depending on the species, documented effects of underwater noise include developmental disruption, poor body condition, increased predation, reduced offspring survival rates, reduced food intake, DNA fragmentation, behavioural changes, masking problems, and physiological responses. Reducing underwater noise from ships would make a significant contribution to protecting affected species. It would also contribute to achieving the environmental objective in relation to descriptor 11 of the MSFD "Introduction of energy (including underwater noise) does not adversely affect the ecosystem". In addition, there is a close connection in some cases between measures to increase energy efficiency and measures to reduce underwater noise from ships. The issue of noise reduction should therefore be considered from the beginning in the climate protection debate and synergies used accordingly.

IMO guidelines for the reduction of underwater noise from ships

In July 2023, the Marine Environmental Protection Committee (MEPC) of the IMO adopted the revised, non-mandatory guidelines for the reduction of underwater radiated noise from shipping Guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life.  (PDF, 169KB, Not barrier-free file.) in order to reduce negative impacts on marine life.

The guidelines recognize the negative impacts of underwater noise on marine life described above and the role of commercial shipping as a major contributor. In many countries, indigenous coastal people who depend on marine life for food, livelihoods and culture are also harmed by underwater noise.

The revised version replaces the previous guidelines from 2014. It summarises the current state of knowledge and provides an overview of current technical and operational measures to reduce underwater noise from ships.

In order to assist ship owners, two different detailed templates for developing a management plan for the reduction of underwater noise are available. The guidelines help designers, ship operators and administrations to develop appropriate measures and assess the potential impact on the energy efficiency of ships.

EU threshold values and regional agreements

In 2022, the European Union set common threshold values for impulsive and continuous underwater noise for the first time as part of the implementation of the Marine Strategy Framework Directive (MSFD). With regard to continuous noise inputs, the new threshold values stipulate that only 20% or less of the habitat of a target species per month of the assessment year may be exposed to noise levels above the Level of Onset of Biologically adverse Effects (LOBE) (≤ 20%).

LOBE is the noise level above which individuals may begin to experience adverse effects and an impairment of their fitness. Examples of adverse effects include behavioural disturbance, stress, reduced communication space and temporary or permanent loss of habitat.

How these limits can be specified with regard to the target species to be considered, the relevant habitats and LOBE is currently being discussed within the framework of the regional conventions for the protection of the North-East Atlantic (OSPAR) and the Baltic Sea (HELCOM). The BSH is actively involved in the processes at the European and regional level. The threshold values will help to promote the protection and sustainable use of the oceans by requiring EU member states to take them into account in their marine strategies and programmes of measures in future.

Round table "Underwater noise and shipping"

The Round Table "Underwater Noise and Shipping" has been organised and conducted by the BSH together with its partners, the German Shipowners' Association (VDR), the German Federation for the Environment and Nature Conservation (BUND) and the German Shipbuilding and Ocean Industries Association (VSM) since 2023. Among other things, the Round Table is intended to support the implementation of the IMO guidelines and to accompany further work at IMO level and as part of the regional processes at OSPAR and HELCOM. The aim of the Round Table is to bring together all stakeholders involved in issues relating to underwater noise and shipping. The focus is on the exchange of information and technical discussions.

Here you will find the minutes and presentations of the Round Table Underwater Noise and Shipping.