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Military Sonar Blamed for Mass Dolphin Strandings
Mass strandings of dolphins and whales could be caused because the animals are rendered temporarily deaf by military sonar, experiments have shown.
Tests on a captive dolphin have demonstrated that hearing can be lost for up
to 40 minutes on exposure to sonar. Hearing is the most important sense for
dolphins and other cetaeceans, and losing it is likely to cause them to
become disorientated and alarmed.
The finding by the Hawaii Institute of Marine Biology may explain several strandings of dolphins and whales in the past decade. Most strandings are still thought to be natural events, but the tests strengthen fears that exercises by naval vessels equipped with sonar are responsible for at least some of them.
The study also suggested, however, that dolphins and whales would usually be
able to swim away fast enough and far enough to escape any ill effects from
sonar.
To induce deafness in the Atlantic bottlenose dolphin, Tursiops truncatus,
the sonar device would have to be loud, close and would need to last for at
least two minutes.
This should give the animals plenty of time to escape but in some circumstances noises can be caught in "underwater sound traps", Aran Mooney, of the University of Hawaii, said.
Sound can become trapped if a layer of warm water lies over cold water. When sound created in the warm zone reaches the cold water it can bounce back instead of travelling though it. This, Dr Mooney said, would have the effect of trapping the sound in the warm layer, where it would bounce around "like a ping-pong ball", giving whales and dolphins little chance of escaping it.
Similar effects could be experienced in parts of the sea with mountains and ravines, where the sound would bounce back and forth.
Dr Mooney said that this could explain three of the best-known strandings that have been linked to military sonar - in the Bahamas, the Canaries and Hawaii - because all three regions had a mountainous underwater topography.
In the Bahamas in March 2000, 16 Cuvier's beaked whales and Blainville's beaked whales and a spotted dolphin beached during a US navy exercise in which sonar was used intensively for 16 hours.
Sound traps might also go some way to explaining why there are only a few mass strandings compared with the frequency with which sonar is used by navy vessels.
"The big question is what causes them to strand," Dr Mooney said. "What we are looking at are animals whose primary sense is hearing, like ours is seeing. Their ears are the most sensitive organ they have.
"What we found was if you play sound you can cause temporary hearing loss. The sounds have to be surprisingly loud and they have to be repeated over an extended period of time - two to three minutes.
"In that time you would expect them to swim away as fast as possible. They have to be within 40 metres of a ship, but when you have certain oceanographic conditions it's hard for the animals to get out of the way."
Observations by researchers while carrying out the tests, which are reported in the journal Biology Letters, showed that even though the dolphin involved was well accustomed to man-made noises and disturbances, it suffered subtle behavioural changes, which could cause further confusion.
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14 Comments so far
Show AllSonar should simply be banned, it is obviously very harmful to cetacean life. It should be banned globally, along with depleted uranium munitions, cluster bombs, and landmines. If the UN had any real power to represent the aspirations of most of the world's people, these bans would already doubtless exist. Why not an article detailing precisely WHY this sonar is so urgently needed by the US (and other?) navies? Instead we get article after article showing that it is likely that sonar has some connection to the whale and dolphin strandings, at least some of the time. It's always as though the burden of proof is on yet another threatened species to prove its endangerment from the latest techno-military nightmare. But of course the US Navy doesn't care, nor does the US military-industrial-entertainment complex. So the whales and dolphins will go on committing mass suicide so the oligarchs can continue with their deluded dream of world domination. How sad.
Is there anything - social or natural - that the US war machine and the resource extraction that fuels it, isn't destroying?
Yes, the wealth of its leaders.
haven't weapons and tactics moved beyond the need for cold war submarine games, if they were ever justifiable? stop blasting these torturous waves through the oceans and these innocent animals...
Could be caused is not caused.
Yes, but could be caused might include caused.
The military has known the effects of SONAR for decades, they just don't care.
I found several corpses of Atlantic bottlenose dolphins on the shore of the Chesapeake Bay in Norfolk (home of the worlds largest naval installation) in the 1980s. The military denied it could have been SONAR but look now.
As I have said before, If they would put some admirals in wet suits, take them down and let them endure the sonar just like the cetaceans, then see what they say about it, if they survive, then I would consider that there had been somewhat adequate testing.
However, we sit topside and theorize while the cetaceans are driving themselves ashore with blood oozing from their sense organs and their brains.
I think the sooner humanity self-destructs, the better off the planet will be, but unfortunately, like the Israelis with their "Sampson Option," we will, no doubt, take most of the life on the planet into oblivion with us when we go.
Navy friends tell me that nuclear subs, appropiately called "Boomers", have a sonar boom loud enough to knock out a scuba diver. At the "Tongue of the Ocean" where Boomers train, there have long been cetacean strandings in the near Bahamas.
It has become "us vs them". "Us" being the MIC and "them" being the whales and dolphins, long lived creatures with larger brains than people have.
Maybe it's a good thing that the HMS Matapan (D43) was turned into razor blades afterall.
The military always seems to get top priority over everything else. We humans truly are a murderous lot.
The darn military is at war with the Earth and the entirety of life.
t_g
We have mass strandings of various dolphin varieties along our Southern Ocean, mainly in Tasmania. We are asking questions, but are never getting answers.
Suppose, there is a dense traffic of submarines along our southern shores - begs the question: WHY??? Who the hell is going to attack us from there? As Australia barely has any serious naval hardware, or formidable enemies - anyway, not from the SOUTH! - dare I say it might be the US Navy dirtying our waters? We are allies, after all. Are they training for an invasion of a waterlogged country? Landing on the beaches of... where? Somewhere along South America?
Just as an aside: a couple of months ago a Qantas jet plunged a couple of thousand metres (!) mid-flight right above a military base in Western Australia and had to make an emergency landing. Passangers had blood pouring out of their ears, noses, etc. and were scared stiff, of course. People were asking questions, of course, so there was an investigation (sort of...). They have uncovered, that the jet just plunged. Just so. No military involvement, whatsover. No lasers, or sounds, or anything. Pls forgive an elderly lady not familiar with technical data... But I am suspicious, nevertheless.
Arent' we the peachiest of species!? Always killing.