The United States Navy has agreed to cut its use of a controversial low-frequency sonar system, which could be harming marine mammals, especially whales and dolphins, an environmental group has said.
Deep-diving whales are most affected
The Natural Resources Defense Council (NRDC) says the decision is the result of a deal hammered out after the group sued the navy over the issue.
Now the military would substantially reduce its use of the system during peacetime, restricting it to certain areas along the eastern coast of Asia, the NRDC said.
Last week, zoologists said they believed many unexplained strandings and deaths of marine mammals could be caused by sound waves from underwater military sonar equipment.
Reduced test area
According to a report carried in the journal Nature, the sonar signals may cause bubbles in the animals' tissue, in much the same way as divers can suffer decompression sickness known as "the bends".
Although the agreement with the navy is not yet permanent, since it must first be approved by a federal magistrate, environmentalists are hailing it as a "groundbreaking" accord.
The new system, which emits a very loud, low frequency sound that can travel for hundreds of kilometres, was due to be tested in oceans worldwide.
Under the agreement it will now only be used in a small fragment of the world's oceans - approximately 2.4 million square kilometres (0.9 million square miles).
There will be further seasonal constraints to give added protection to migrating whales.
However, none of the restrictions apply during wartime.
"This agreement safeguards both marine life and national
security," Joel Reynolds, director of the Marine Mammal Protection Project at the NRDC said.
"It will prevent the needless injury, harassment, and death of countless whales, porpoises and fish, and yet allow the Navy to do what is necessary to defend our country."
Military sonar has been very much in the news recently, with zoologists describing how 14 whales died during a naval exercise in the Canary Islands.
About four hours after "the onset of mid-frequency sonar activity" all 14 stranded themselves and then died on the beaches of Fuerteventura and Lanzarote, the Nature report said.
On Monday conservations presented an 85,000-signature petition to Nato's Brussels headquarters demanding that the bloc implement an immediate ban on all use of the sonar system.
Images copyright and courtesy of Guayarmina Brito.