Underwater noise can de classified according to its source:

  • physical source: wind, storms, waves, turbulence, earthquake, seabed, icebergs etc.;
  • biological source: sounds produced by animals or as a result of their movement;
  • anthropogenic source: human activities (boats, geological exploration, military activities etc.).

A number of recent studies have shown that marine noise caused by marine traffic continues to increase. From 1950 to 2000, low-frequency sound doubled every ten years. The cause is related to the number of boats, which trebled, and their ever-increasing size.

While we need to remain particularly cautious in assessing the impact that noise has on marine mammals, a number of scientific studies provide accounts of behavioral changes.

Anthropogenic marine noise is a form of pollution that, while widely recognized, is almost entirely unregulated. We know that a number of species of fish and marine mammals are very sensitive to noise and use it to orientate themselves, find food, locate partners, avoid predators and communicate with each other. It has been shown, for example, that there is a relationship between the noise from human activities and bycatch and ship strike events, the noise preventing animals from detecting fishing nets and boats.

As we industrialize our seas, the problem of marine noise pollution is growing. A number of noise sources combine, particularly marine traffic, oil and gas exploration and production sites for these raw materials, dredging, construction work and military activities, and are the reason for the huge increase in noise levels in seas everywhere. In the last ten years, studies show that certain types of marine noise can kill, injure and deafen whales and other marine mammals as well as fish. In particular, there is a proven link between multiple marine mammal strandings and deaths and exposure to military sonar. It has also been shown that certain animals affected do not strand themselves but die at sea. Lastly, it has been found that intense noises have a damaging effect on various species of fish that are caught for commercial purposes, and notably results in habitats lost, limited reproductive abilities and a greater susceptibility to illness. One study even revealed that fishermen’s catches were reduced from 45 to 70% by the use of air cannons.

As with other types of pollution that require multilateral regulation, marine noise pollution is a cross-border issue. Major sources of marine noise, such as military sonar and marine transport, can be propagated over hundreds of kilometers.


Management options

The current level of understanding in relation to the issue of underwater noise is still too limited to enable adequate and effective management options to be implemented. However, in response to this growing problem, a number of intergovernmental bodies have acknowledged that marine noise constitutes a threat to the marine environment and are thus calling for the precautionary principle to be adopted when managing activities that create noise across the world’s oceans.

Regarding noise from marine traffic, a real-time mapping system has been conducted in French waters of the Pelagos Sanctuary and published online by SINAY in the framework of the National Research Program of the French Part to the Agreement.

While risks to marine mammals are believed to exist in the Pelagos Sanctuary, a consultative process concerning construction at sea, is in place within it. A request for works permits must first be filed with the supervising authority, which then refers to the concerned Part of the Pelagos Sanctuary for its opinion. This Part consults the specific groups involved, who give their advices on the issue.

Concerning military sonars, Italian Part of the Pelagos Sanctuary, has issued a unilateral proclamation that they will not use within the area.

Lastly, as regards seismic exploration (seeking oil and other materials) and the major risk of temporary or permanent deafness or damage to echolocation systems, the Pelagos Sanctuary as a SPAMI may give a negative opinion on this issue.

In October 2007, at the Third Meeting of the Contracting Parties to the ACCOBAMS Agreement, the participants made various recommendations for management measures relating to underwater noise:

  • Prohibiting the use of military sonar within the Sanctuary, especially because of the presence of Cuvier’s beaked whales, a species that is particularly sensitive to acoustic disturbances.
  • Prohibiting seismic exploration within the Sanctuary. Ensuring that large fin whale habitats are protected, as the species is known to be sensitive to this type of noise, but also to in order protect other species.
  • Creating a buffer zone to stop seismic noise, which would extend to the west, parallel to the Sanctuary, and offer additional protection to sperm whales.
  • Working with the International Maritime Organization and marine transport and ferry companies in order to change the routes of certain shipping lanes, so that they avoid species that are sensitive to such noise (and for whom there is a risk of collisions)
  • Carrying out new research into shipping lane routes. Monitoring boats’ movements using surveillance systems such as automatic identification systems and monitoring other acoustic activities using strategically placed passive acoustic monitoring buoys.
  • Encouraging the Permanent Secretariat of the Pelagos Sanctuary to enter into discussions with the marine transport companies operating in the area to persuade them to use noise-limiting technology on vessels.
  • Strengthening the current stranding network, enabling it to carry out autopsies that are deemed necessary in order to detect gas and fat embolic syndrome, lesions caused by ship strikes etc. (as well as training activities and the creation of a tissue bank).

For the record, it is worth noting that the issue was also the subject of a number of international recommendations issued by organizations including ASCOBANS (2003), IWC (2004), the European Parliament (2004), IUCN (2004) etc.

In addition, the Pelagos Sanctuary is a member of ACCOBAMS / ASCOBANS working group on anthropogenic noise. 

It is clear that the international community actively supports multilateral efforts to combat marine noise pollution, which is a dangerous threat to the marine environment. We believe that it is incumbent on the relevant UN groups, particularly the signatories of the United Nations Convention on the Laws of the Sea (UNCLOS), to build on this desire and lead the movement to investigate ways of regulating marine noise, which is polluting the planet’s oceans.