Credit: By Simon Johnson, The Telgraph, www.telegraph.co.uk 15 March 2011
Offshore wind farms are one of the main reasons why whales strand themselves on beaches, according to scientists studying the problem.
Environmentalists have blamed submarines’ sonar and a ground-breaking study has confirmed that sonar does disturb the navigation of whales but it has suggested that offshore wind farms, as well as oil rigs, and even passing ships, posed an even greater threat.
Scientists at the University of St Andrews studying beaked whales, a species that frequently becomes beached in Britain, concluded that they were extraordinarily timid creatures that were scared “by virtually anything unusual”, despite being the size of a rhinoceros and weighing the same as a London bus.
The findings suggest that more strandings can be expected as ministers are planning a major expansion in the number of offshore wind farms, especially off the coast of Scotland, which is an area where whales congregate to feed.
In an attempt to gauge the effect of different noises on beaked whales, scientists played sonar sounds to whales in the wild and tracked their responses using an electronic tag attached to the mammals.
The tag measured all the sounds heard by the whales and their subsequent swimming movements.
Prof Ian Boyd, the project’s chief scientist, said: “There has always been an association with sonar and the stranding of beaked whales, but now we really have proof this is the case.
“The sonar sounds that are used in naval anti-submarine exercises to detect submarines probably makes the beaked whales ‘get herded’ and pushed ashore. “But, maybe even more importantly, we have discovered that beaked whales are scared by virtually anything unusual.”
He said other sounds were more dangerous than sonars because they could be heard constantly. This might affect the feeding and reproductive cycles of whales.
“The general levels of sound that humans make in the ocean from all sorts of sources like ships, oil and gas exploration and renewable energy may be a much more serious problem for beaked whales and some other sensitive species,” he said. The research showed the whales were much more responsive to lower levels of sonar than previously thought, and that they moved quickly to avoid the sound.
Prof Boyd concluded that in some unusual circumstances they are unable to escape the area, become confused and disorientated and end up stranded.
Although the beaked whales in the trial had heard sonar before, they were still frightened by it and did not appear to have developed any form of “immunity”.
Now the link between noise pollution and strandings has been proven, he said he hoped new, quieter ships could be designed and their sonar could be switched off when not in use.
About a dozen whales – usually beaked or sperm whales – become stranded in Britain every year.
The Hebridean Whale and Dolphin Trust, a charity that monitors whales off the Scottish coast, branded the report “crucial” and said scientists were only now beginning to appreciate the mammals’ sensitivity to noise. A spokesman said she was concerned about “loud or persistent” sounds being added to the seas every year in the form of more ships and wind farms.