As the world’s oceans get busier, they are also getting a lot nosier. The increase in noise has an alliance of wildlife groups concerned about the effect on marine mammals. The world’s oceans and seas are becoming noisier as a result of increases in the number and size of vessels; a rise in seismic surveys and because of the new generation of military sonars, the alliance recently said at the United Nations Environment Programme’s Convention on Migratory Species conference in Rome.

The alliance is concerned that the cacophony of sounds pervading the seas are increasing threats to marine mammals who use sound, sometimes over great distances, to communicate, forage for food and find mates. The alliance is urging governments and industry to adopt quieter engines for ships, tighter rules on the use of seismic surveys in oil and gas exploration and new, less intrusive sonar technologies by the various militaries around the world.

The International Fund for Animal Welfare’s report Ocean Noise Turn It Down, found that: the distance over which blue whales can communicate has been cut by 90% as a result of increased noise levels; airguns used in seismic surveys generate colossal sounds peaking at up to 259 decibels and can be repeated every 10 seconds for weeks or months on end; there are an estimated 300 naval sonar systems world-wide able to generate pressure sound waves of more than 235 decibels and increasingly new kinds of low frequency sonar are being developed and deployed.

The alliance also expressed concerns that rising levels of carbon dioxide, the result of the burning of fossil fuels, may be aggravating noise levels from increased human activities. Researchers at the Monterey Bay Aquarium Research Institute in the United States are also suggesting that increasing ocean acidity may be making the marine environment noisier. The changing chemistry of seawater means that currently the water is 10 % less absorbent of ‘low’ frequency sound than it was prior to the Industrial Revolution.

Mark Simmonds Science Director of the Whale and Dolphin Conservation Society, explains, ”Underwater, man-made noise, is already triggering a kind of acoustic fog. In addition there is now evidence linking loud underwater noises with some major strandings of marine mammals…”.

He said there was also emerging evidence that certain tissue damage in cetaceans is linked to noise, with a probable mechanism being that startled animals exhibit unusual diving behaviour and suffering something similar akin to a human diver getting the ‘bends’.

The European Community and its member states have submitted a draft resolution to the 9th Conference of the Parties to the UNEP-CMS this week urging members of the treaty to consider a wide range of measures to tackle underwater noise. Measures being suggested include ‘noise protection areas’ in enclosed seas and sea basins; greater monitoring of noise and noise databases that list where man-made sounds are coming from.


The Whale and Dolphin Conservation Society: www. wdcs. org
WDCS Oceans of Noise Report: www. wdcs. org/publications. php
The International Fund for Animal Welfare: www. ifaw. org

IFAW Ocean Noise Turn It Down – A report on ocean noise pollution.

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