Silence Please: The Issue of Underwater Sound Pollution


In 2011, 19 pilot whales stranded off the coast of Scotland. This is just one out of many such events that have taken place over the past decades. The reason why these kinds of mass whale strandings occur is, however, unclear. Yet, since the latter half of the 1980s, there has been increasing evidence to back up the theory that military sonar exercises play a role in these strandings. Military sonar exercises and excessive underwater noise are just some of many causes of mass whale strandings. Since this remains such an unknown and undebated topic, it is worth examining the origins of excessive underwater noise, as well as its effects.

When you hear the term underwater noise pollution, the first thing to realize is that it can be noisy underwater too. Underwater noise pollution is essentially (excessive) noise that is produced, transmitted, and scattered in the ocean. While keeping in mind that there are also naturally produced sounds from marine mammals, rain, and the breaking of waves, human activities also produce sound in the ocean. Actually, human produced noise, at excessive levels, can have severe and detrimental effects on the marine environment, especially on marine animals. Oil and gas exploration and exploitation, mining, fishing equipment, navigation, scientific research, defense applications, aquaculture, and seafloor mapping can all produce sounds that travel hundreds or even thousands of kilometers in the ocean.

Underwater noise has several effects. For example, with regard to marine mammals, excessive noise can damage hearing ability, cause physical injury, as well as heightened stress levels, which in turn may weaken the immune systems of marine life. Moreover, marine mammals heavily rely on sound for navigation, communication and to locate food, mates and predators. Finally, underwater noise also affects the behavior in marine mammals, in that it may disrupt breeding, calving, and the use of migration routes and feeding grounds.

As mentioned before, military sonar is said to have caused a number of mass whale strandings all around the world. Even so, progress in regulating underwater noise pollution has been slow. One of the more obvious problems is that underwater noise pollution is a kind of pollutant that most people are not even aware of. In contrast to plastic pollution or CO2 emmissions, humans are not confronted with the effects of sound, meaning it remains an largely unconsidered issue.

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The next step is to ask: What to do? Underwater noise as a pollutant has only relatively recently become an issue on regional, national and international agendas. Therefore, awareness about underwater noise as a pollutant must be raised and spread across different levels and parts of society. It is included in some environmental impact assessment procedures and receives increased attention in international and regional forums. Nevertheless, underwater noise pollution is still far from being a widely recognized pollutant, voluntarily or mandatorily. It needs to become an integral part of environmental policy, which can partly be realized by including underwater noise pollution when conducting environmental impact assessments.

It is important to keep in mind that noise pollution is just one kind of pollution marine animals are exposed to. The integration of underwater noise pollution in environmental impact assessments is an option to successfully incorporate the consideration of underwater noise pollution into the decision-making process, together with other pollutants. Maybe it would even lead to the development of technology mitigating noise emitted.

Kena Hinzen is currently an LL.M. student in Law of the Sea at the Arctic University of Norway. She obtained her LL.B. in International and European Law at the University of Groningen, the Netherlands, in 2015. Her main interests are in the law of the sea, maritime law, and energy law.


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