Effects of Ocean Noise

Strong evidence now demonstrates that loud underwater sounds can prove fatal to whales. There is still much to learn about the effects of noise on the marine environment, which may prove to be even more devastating than currently realised. What we know for certain, however, is that underwater noise poses a serious threat to marine life.

The effects of ocean noise on whales range from disturbance to temporary hearing loss to permanent physical damage and even death, with exposure to increasing noise levels. The effects of shipping noise are likely to be limited to disturbance. However, even disturbance can have potentially serious consequences if, for example, whales leave their feeding grounds or cannot echo-locate or communicate effectively.

The ways in which sound can disturb whales and the impact that this has on their lives is still not well understood. Some whales appear to move to avoid the noise of ships, others change their behaviour by making longer or louder calls in the presence of noise, while others show no obvious reaction. However, we cannot say that there is no effect just because we do not observe a reaction. Even in people, the stress induced by living in a noisy environment is not always apparent in their observed behaviour.

The effects of underwater noise pollution on whales

Loud ocean noise can undermine the acoustic signals of whales by “masking” them, reducing the whales' ability to detect relevant sounds in the presence of other sounds of similar frequencies. The dramatic increase in background noise levels can be harmful to whales because it reduces their ability to hear predators, detect prey, navigate migratory routes, and communicate with others.

Some very loud manmade noises may also force whales to surface from deepwater. There is some evidence that, together with the effects of noise, this can cause injuries similar to decompression sickness or “the bends” – the illness that can kill scuba divers who surface too quickly. Intensive sound waves or shockwaves from explosions, drilling or seismic activity can also cause physical damage.

Mass Whale Strandings

Military high-intensity sonar testing fields have also been directly linked to a number of mass whale stranding incidents. Stranded whales in the vicinity of sonar testing areas have provided clear evidence of the potentially fatal effects of sonar.

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IFAW NRDC Underwater Noise Report