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
Life and Style
love + sex A new study has revealed the average size - but does that leave men outside the 'normal' range being thought of as 'abnormal'?
Arts and Entertainment
TV
Voices
The Palace of Westminster is falling down, according to John Bercow
voices..says Matthew Norman
Sport
Steve Bruce and Gus Poyet clash
football
News
Graham Norton said Irish broadcaster RTE’s decision to settle was ‘moronic’
TV
Arts and Entertainment
Jake and Dinos Chapman were motivated by revenge to make 'Bring me the Head of Franco Toselli! '
arts + ents Shapero Modern Gallery to show explicit Chapman Brothers film
Arts and Entertainment
Kurt Cobain performing for 'MTV Unplugged' in New York, shortly before his death
music Brett Morgen's 'Cobain: Montage of Heck' debunks many of the myths
ebooks
ebooksA special investigation by Andy McSmith
Life and Style
life
Sport
Brendan Rodgers
football The Liverpool manager will be the first option after Pep Guardiola
News
Amazon misled consumers about subscription fees, the ASA has ruled
news
Arts and Entertainment
Myanna Buring, Julian Rhind-Tutt and Russell Tovey in 'Banished'
TV Jimmy McGovern tackles 18th-century crime and punishment
Arts and Entertainment
Paul Whitehouse as Herbert
arts + ents
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: Lettings and Sales Negotiator - OTE £46,000

£16000 - £46000 per annum: Recruitment Genius: This is an opportunity to join ...

Recruitment Genius: Home Care Worker - Reading and Surrounding Areas

£9 - £13 per hour: Recruitment Genius: This is a great opportunity to join a s...

Recruitment Genius: Key Sales Account Manager - OTE £35,000

£25000 - £35000 per annum: Recruitment Genius: Have you got a proven track rec...

Recruitment Genius: Sales Executive - OTE £40,000

£15000 - £18000 per annum: Recruitment Genius: This is a great opportunity for...

Day In a Page

Syrian conflict is the world's first 'climate change war', say scientists, but it won't be the last one

Climate change key in Syrian conflict

And it will trigger more war in future
How I outwitted the Gestapo

How I outwitted the Gestapo

My life as a Jew in wartime Berlin
The nation's favourite animal revealed

The nation's favourite animal revealed

Women like cuddly creatures whilst men like creepy-crawlies
Is this the way to get young people to vote?

Getting young people to vote

From #VOTESELFISH to Bite the Ballot
Poldark star Heida Reed: 'I don't think a single bodice gets ripped'

Poldark star Heida Reed

'I don't think a single bodice gets ripped'
The difference between America and Israel? There isn’t one

The difference between America and Israel? There isn’t one

Netanyahu knows he can get away with anything in America, says Robert Fisk
Families clubbing together to build their own affordable accommodation

Do It Yourself approach to securing a new house

Community land trusts marking a new trend for taking the initiative away from developers
Head of WWF UK: We didn’t send Cameron to the Arctic to see green ideas freeze

David Nussbaum: We didn’t send Cameron to the Arctic to see green ideas freeze

The head of WWF UK remains sanguine despite the Government’s failure to live up to its pledges on the environment
Author Kazuo Ishiguro on being inspired by shoot-outs and samurai

Author Kazuo Ishiguro on being inspired by shoot-outs and samurai

Set in a mythologised 5th-century Britain, ‘The Buried Giant’ is a strange beast
With money, corruption and drugs, this monk fears Buddhism in Thailand is a ‘poisoned fruit’

Money, corruption and drugs

The monk who fears Buddhism in Thailand is a ‘poisoned fruit’
America's first slavery museum established at Django Unchained plantation - 150 years after slavery outlawed

150 years after it was outlawed...

... America's first slavery museum is established in Louisiana
Kelly Clarkson: How I snubbed Simon Cowell and become a Grammy-winning superstar

Kelly Clarkson: How I snubbed Simon Cowell and become a Grammy-winning superstar

The first 'American Idol' winner on how she manages to remain her own woman – Jane Austen fascination and all
Tony Oursler on exploring our uneasy relationship with technology with his new show

You won't believe your eyes

Tony Oursler's new show explores our uneasy relationship with technology. He's one of a growing number of artists with that preoccupation
Ian Herbert: Peter Moores must go. He should never have been brought back to fail again

Moores must go. He should never have been brought back to fail again

The England coach leaves players to find solutions - which makes you wonder where he adds value, says Ian Herbert
War with Isis: Fears that the looming battle for Mosul will unleash 'a million refugees'

The battle for Mosul will unleash 'a million refugees'

Aid agencies prepare for vast exodus following planned Iraqi offensive against the Isis-held city, reports Patrick Cockburn