Seas alive with sound of whale song

The seas off Britain and Western Europe are alive with the sound of whale song, a highly sensitive US hydrophone system has revealed, writes Nicholas Schoon.

Even the rarest and largest of the whales, the blue, is often heard in Atlantic waters beside the UK.

The mysterious vocalisations of the great sea mammals have been recorded using arrays of hydrophones fixed to the sea-bed as deep as 10,000ft. They were laid in the North Atlantic to detect Soviet nuclear submarines heading out on patrol or returning to port.

Now the whale sounds they picked up have been made available to US and British scientists who are highly enthusiastic about their value in studying numbers, ecology and behaviour.

The blue has the loudest song; a pure basso profundo tone lasting some 15 seconds at between 10 and 20 hertz (cycles per second). In air it would be too low for the human ear to hear, although you might feel the atmosphere rattle.

Christopher Clark, head of bioacoustics research at Cornell University in New York State, said: ''You can have a hydrophone in the Caribbean picking up a blue whale singing off Newfoundland, a couple of thousand miles north.

''Whenever you listen on these arrays you can hear between 10 and 100 singing across the North Atlantic. Some days it's like going into the woods on a spring morning and hearing all the birdsong.''

The sound is thought to be used to attract mates, but because it is heard out of the mating season, can carry huge distances in deep water and echoes off islands and coasts, Dr Clark believes the song is also a navigational aid.

Two years of listening to the recordings have shown there are populations of blue, fin, humpback and minke whales which remain all year round in the waters off Britain and Norway. But the numbers of blue, once hunted to the brink of extinction, are still small: in the entire North Atlantic there are only thought to be around a thousand.