Beaked whales are frightened by unusual noise including soundwaves caused by underwater military sonar used to detect submarines, according to a new study.

Researchers at the University of St Andrews worked on a study in the Bahamas into the effects of sounds on the behaviour of the rarely-seen mammal.

They found that beaked whales are particularly sensitive to unusual sounds.

The team played sonar sounds to whales in the wild and measured their resulting swimming responses using an electronic tag.

Ian Boyd, professor and chief scientist on the study, said: “We showed that the animals reacted to the sonar sound at much lower levels than had previously been assumed to be the case.

“We stopped exposing the animals to the sounds before there were any dangerous effects but it was clear that these whales moved quickly out of the way of the sonars.

“We now think that, in some unusual circumstances, they are just unable to get out of the way and this ends up with the animals stranding and dying.

“There was always a strong association between the death of these strange, little-known animals and naval exercises. We have now shown that this may well be the case.”

However, the researchers are cautious to note that these effects might be caused by noise other than sonar signals.

Prof. Boyd said: “There is a tendency to blame the Navy for every stranding event and that is ridiculous. We are now beginning to understand that some species of whales and dolphins appear to be much more robust to disturbance by sound than others.”