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Last Updated: Thursday, 18 May 2006, 10:09 GMT 11:09 UK
Project to probe impact of sonar
Orca, AP
Cetaceans now navigate an "acoustic fog" say scientists
A team of scientists from Scotland is proposing to carry out experiments on killer whales in the wild in order to study their reaction to sound.

Biologists from the University of St Andrews in Fife want to work out at what frequencies and volume the orcas show signs of stress.

Sound is considered as important to some marine mammals as sight is to us.

Some scientists believe that military sonar - powerful sound waves - could be harming whales and dolphins.

The issues are examined on Thursday in the BBC Radio 4 programme Costing the Earth.

A few metres below the waves, sound is the only way to communicate, navigate or hunt.

Yet oceans are now full of background noise from shipping, drilling and naval exercises. Cetaceans (whales, dolphins and porpoises) have to swim through what some researchers described as "acoustic fog".

Sonic stress

A report released in February by the Inter-agency Committee on Marine Science and Technology said research into the effects of sound in the oceans on marine mammals should be commissioned by the UK government.

The report identified 13 cases of strandings by whales and dolphins which appear to have been linked to specific sources of noise; most of those sources involved naval vessels.

Post-mortem evidence gathered after a number of whales beached themselves during military exercises in the Canary Islands four years ago indicated the presence of tiny gas bubbles in the animals' internal organs, particularly the liver, which scientists believe is linked somehow to sonar.

A team from the Sea Mammal Research Unit at St Andrews wants to attach transmitters to a pod of orcas off Norway and study their behaviour as they turn up the sonar.

When they show signs of stress by swimming away or not feeding, the sound would be stopped.

The researchers argue this is the only way to prove exactly how sound waves affect cetaceans so they can advise navies or geologists how to avoid harming marine mammals.

But some animal welfare groups are uneasy, saying the research only yields results when the animal begins to suffer.

Costing The Earth is on BBC Radio 4 on Thursday at 2100. The programme is repeated on Friday at 1500.

Research needed on marine sound
13 Feb 06 |  Science/Nature
Whale stranding cases 'increase'
09 Mar 05 |  Science/Nature


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