Military exercises blamed for whales stranded on beach

Military exercises involving blasts of underwater sound could be the reason why whales and dolphins become stranded on beaches, a study has found.

Military exercises involving blasts of underwater sound could be the reason why whales and dolphins become stranded on beaches, a study has found.

The blasts from active sonar, used to detect submarines, may cause dolphins and whales to suffer a form of decompression sicknesssimilar to "the bends" suffered by deep-sea divers.

Scientists believe they have found evidence to explain why many strandings of whales and dolphins appear to coincide with naval exercises involving active sonar.

Marine mammologists discovered signs of decompression sickness during post-mortem examinations of whales which beached themselves in the Canary Islands four hours after the start of a Spanish naval exercise in September 2002, where active sonar was used.

Antonio Fernandez, professor of pathology at the University of Las Palma de Gran Canaria, who examined 14 beaked whales found beached in the area where the exercise took place, said the link was circumstantial but strong.

"The detailed examination of the mass-stranded beaked whales in the Canaries in 2002 suggests that naval sonar could induce a condition similar to decompression sickness," Professor Fernandez said. "More research is needed to confirm this mechanism and to determine what level of sound can induce this process in exposed whales and dolphins."

The study, in the journal Nature, also involved government-funded British scientists who have performed more than 2,500 post-mortem examinations on sea mammals stranded off Britain over the past decade.

Paul Jepson, of the Institute of Zoology in London and a member of the Anglo-Spanish team, said: "The link between military sonar and stranded sea mammals has been established. Our study suggests a potential mechanism."

Decompression sickness happens when dissolved gases in the tissues of a diving mammal come out of solution because the animal rises to the surface too quickly. The dissolved gases, mostly nitrogen, form bubbles which can press against nerves and joints to cause severe pain and tissue damage. Dr Jepson said examination of stranded sea mammals in Britain showed that they can experience the effects of decompression sickness, challenging the notion that cetaceans (whales and dolphins) cannot suffer from the bends.

In some beached sea mammals, gas cavities had formed to such an extent in their livers that the texture of the dissected organs looked like aerated chocolate, Dr Jepson added. "A small number of stranded animals had gas bubbles and associated tissue injuries.

"Although decompression sickness was previously unheard of in marine mammals, we concluded that a form of marine mammal decompression sickness was the most likely cause."

The scientists have ruled out bacterial infections or other post-mortem changes to the corpses as the possible causes of the tissue bubbles. But an unresolved question is: how does active sonar causes decompression sickness? The most obvious answer is that the sudden loud noises, greater than any natural underwater sound, may startle whales and dolphins, causing them to surface too quickly.

Beaked whales, such as bottlenose and sperm whales, dive to great depths and normally take many minutes to surface, slowly allowing dissolved gases in their bloodstream to be released into the lungs. Anything that interferes with this carefully evolved behaviour may increase the risk of decompression sickness, leading to disorientation and stranding.

Another possibility, proposed by Dorian Houser, of the US Navy marine mammal programme in San Diego, is that sound waves from active sonar interfere with the way diving sea mammals safely store dissolved gases.

Dr Houser has proposed a mathematical model of how sonic blasts have a direct impact on dissolved gases by vibrating microscopic bubbles in the bloodstream, causing them to expand to a size that can cause tissue damage.

The work, which was largely theoretical, found the diving behaviour of beaked whales, which gulp a large amount of air before a dive, makes them more vulnerable to this effect because levels of super-saturated nitrogen in their bloodstream can more than triple by the end of a dive.

Other sea mammals, such as seals, breathe out before a dive, which allows their lungs to collapse at a shallower depth. This helps prevent nitrogen building in the bloodstream while they are underwater.

Start your day with The Independent, sign up for daily news emails
News
US comedian Bill Mahr
people
Voices
Winston Churchill, then prime minister, outside No 10 in June 1943
voicesA C Benson called him 'a horrid little fellow', George Orwell would have shot him, but what a giant he seems now, says DJ Taylor
Sport
football
News
Rob Lowe
peopleRob Lowe hits out at Obama's snub of Benjamin Netanyahu
PROMOTED VIDEO
News
Davies (let) says: 'Everybody thought we were having an affair. It was never true!'
people'Our friendship flourished online. You can share some very revelatory moments at four in the morning…'
Arts and Entertainment
Over their 20 years, the band has built a community of dedicated followers the world over
music
News
Staff assemble outside the old City Road offices in London
mediaThe stories, the writers and the changes over the last quarter of a century at Britain's youngest paper
Life and Style
The Oliver twins, Philip and Andrew, at work creating the 'Dizzy' arcade-adventure games in 1988
techDocumentary looks back at origins of the computer-games industry
Arts and Entertainment
Krall says: 'My hero player-singer is Elton John I used to listen to him as a child, every single record
music
News
Friends for life … some professionals think loneliness is more worrying than obesity
scienceSocial contact is good for our sense of wellbeing - but it's a myth that loneliness kills, say researchers
ebooks
ebooksA year of political gossip, levity and intrigue from the sharpest pen in Westminster
Arts and Entertainment
The Wu-Tang Clan will sell only one copy of their album Once Upon A Time In Shaolin
musicWu-Tang Clan and The Sexual Objects offer fans a chance to own only copies of their latest albums
News
i100
Environment
Number so freshwater mussels in Cumbria have plummeted from up to three million in the 20th century to 500,000
environment
Life and Style
Models – and musicians – on the catwalk in Dior Homme for the men’s 2015/16 fashion show in Paris
fashionAt this season's Paris shows, various labels played with the city boys' favourite
News
i100
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Sales Consultant - Solar Energy - OTE £50,000

£15000 - £50000 per annum: Recruitment Genius: Fantastic opportunities are ava...

Recruitment Genius: Compute Engineer

Negotiable: Recruitment Genius: A Compute Engineer is required to join a globa...

Ashdown Group: PHP Web Developer / Website Coordinator (PHP, JavaScript)

£25000 - £28000 per annum + 25 days holidays & pension: Ashdown Group: PHP Web...

Recruitment Genius: Estates Projects & Resources Manager

£35000 - £40000 per annum: Recruitment Genius: Based in London, Manchester, Br...

Day In a Page

Iraq invasion 2003: The bloody warnings six wise men gave to Tony Blair as he prepared to launch poorly planned campaign

What the six wise men told Tony Blair

Months before the invasion of Iraq in 2003, experts sought to warn the PM about his plans. Here, four of them recall that day
25 years of The Independent on Sunday: The stories, the writers and the changes over the last quarter of a century

25 years of The Independent on Sunday

The stories, the writers and the changes over the last quarter of a century
Homeless Veterans appeal: 'Really caring is a dangerous emotion in this kind of work'

Homeless Veterans appeal

As head of The Soldiers' Charity, Martin Rutledge has to temper compassion with realism. He tells Chris Green how his Army career prepared him
Wu-Tang Clan and The Sexual Objects offer fans a chance to own the only copies of their latest albums

Smash hit go under the hammer

It's nice to pick up a new record once in a while, but the purchasers of two latest releases can go a step further - by buying the only copy
Geeks who rocked the world: Documentary looks back at origins of the computer-games industry

The geeks who rocked the world

A new documentary looks back at origins of the computer-games industry
Belle & Sebastian interview: Stuart Murdoch reveals how the band is taking a new direction

Belle & Sebastian is taking a new direction

Twenty years ago, Belle & Sebastian was a fey indie band from Glasgow. It still is – except today, as prime mover Stuart Murdoch admits, it has a global cult following, from Hollywood to South Korea
America: Land of the free, home of the political dynasty

America: Land of the free, home of the political dynasty

These days in the US things are pretty much stuck where they are, both in politics and society at large, says Rupert Cornwell
A graphic history of US civil rights – in comic book form

A graphic history of US civil rights – in comic book form

A veteran of the Fifties campaigns is inspiring a new generation of activists
Winston Churchill: the enigma of a British hero

Winston Churchill: the enigma of a British hero

A C Benson called him 'a horrid little fellow', George Orwell would have shot him, but what a giant he seems now, says DJ Taylor
Growing mussels: Precious freshwater shellfish are thriving in a unique green project

Growing mussels

Precious freshwater shellfish are thriving in a unique green project
Diana Krall: The jazz singer on being friends with Elton John, outer space and skiing in Dubai

Diana Krall interview

The jazz singer on being friends with Elton John, outer space and skiing in Dubai
Pinstriped for action: A glimpse of what the very rich man will be wearing this winter

Pinstriped for action

A glimpse of what the very rich man will be wearing this winter
Russell T Davies & Ben Cook: 'Our friendship flourished online. You can share some very revelatory moments at four in the morning…'

Russell T Davies & Ben Cook: How we met

'Our friendship flourished online. You can share some very revelatory moments at four in the morning…'
Bill Granger recipes: Our chef serves up his favourite Japanese dishes

Bill Granger's Japanese recipes

Stock up on mirin, soy and miso and you have the makings of everyday Japanese cuisine
Michael Calvin: How we need more Eric Cantonas to knock some sense into us

Michael Calvin's Last Word

How we need more Eric Cantonas to knock some sense into us