Proof that whales flee sonar
Research may explain mass strandings of marine mammals including dolphins
Scientists have proved that whales flee from military sonar used to hunt submarines, providing a possible explanation for studies that have connected naval exercises around the world to unusual mass strandings of whales and dolphins.
Beaked whales, the most common casualty of the strandings, were shown to be highly sensitive to sonar. But a second study also revealed unexpectedly that blue whales, the largest animals on Earth, which have suffered a 95 per cent decline in the past century, also abandoned feeding and swam rapidly away from sonar noise.
The strong response observed in the beaked whales occurred at noise levels that were well below those allowed for US Navy exercises.
"This result has to be taken into consideration by regulators and those planning naval exercises," said Stacy DeRuiter, at the University of St Andrews in Scotland, who led one of the teams in the study.
Sarah Dolman, at the Whale and Dolphin Conservation charity, said: "For whales and dolphins, listening is as important as seeing is for humans - they communicate, locate food and navigate using sound.
"Noise pollution threatens vulnerable populations, driving them away from areas important to their survival, and at worst injuring or even causing the deaths of some whales and dolphins."
Dolman said there was an urgent need to re-evaluate the environmental impacts of military activities. The US Navy part-funded the studies, but said the findings showed behavioural responses, not actual harm.
Nonetheless, Kenneth Hess, a navy spokesman, said: "We will evaluate the effectiveness of our marine-mammal protective measures in light of [the] new research findings."
Unusual mass strandings, where multiple species of whale and dolphin beach at several locations simultaneously, have soared since military sonar was introduced in the 1950s.
Beachings can be fatal to these marine mammals.
Beaked whales are the most common species caught up in unusual mass strandings, perhaps because they are more scared by noises sounding like killer whales.