It's war in the water - scientist

While the world is focused on the dramatic campaign to stop Japanese whaling in Antarctic waters, conservationists are focused on a less known threat to marine mammals. And this time the target is the US Navy.

Protesters have until Monday to file comments against a National Marine Fisheries Service (NMFS) plan to allow the Navy to use active sonars [which emit intense sound and listen for echoes; passive sonar detects ambient noise] and explosives during anti-submarine warfare exercises off the Gulf of Mexico, Hawaii, Southern California and the Atlantic Seaboard. The service is charged with enforcing the Marine Mammal Protection Act.

The Navy's "take"- an umbrella term for deaths, plus injuries such as deafness and disruption to breeding, feeding and migration - caused by active sonar, ship strikes and explosions would affect whales, dolphins, seals and other marine animals 31 million times between 2014 and 2019.

"The numbers are staggering," says Giulia Good Stefani, an attorney with the National Resources Defence Council's (NRDC) Marine Mammal Protection Project. "The 31 million instances is a 1300 per cent increase in harm from the past. In California they've gone from saying they were going to harm 700,000 marine mammals to 8.8 million. On the east coast the increase is similar." Underwater explosions are to increase to 50,000. "One scientist we talked to said it's like a war in the water."

The council, allied with Earthjustice and other US and foreign conservation groups against the NMFS proposal, says the new rules would cause 5000 serious injuries and more than 1000 deaths, "a toll three times higher than the impacts of any previous Navy plan".

"The Navy and the NMFS have changed the modelling they use to predict the effects of sonar on the behaviour of marine mammals," explains Steve Mashuda, an attorney with the San Diego office of conservation group Earthjustice. "For years they assumed the onset of temporary hearing loss occurred at 198 decibels [dB]. They've now lowered that to 178dB.

"So the amount and the extent of harm jumps dramatically." Mashuda says 31 million instances does not mean 31 million animals. Instead, it is likely the same animal will be impacted more than once.

This is bad news for whales and other marine mammals, which are heavily dependent on their hearing ability to survive. Permanent deafness would leave victims "essentially dead in the water," says Good Stefani.

Low-frequency noise from the Surveillance Towed Array Sensor System measures 230dB, louder than a fighter jet at take-off, and registers 140dB [which the NRDC says is "a hundred times more intense than the level known to alter the behaviour of large whales"] at 640km.

The NMFS estimates the take would include 60,000 instances of temporary hearing loss among grey whales off the California coast. "Yet there are less than 20,000 grey whales left," says Good Stefani. "So you're talking about temporary hearing loss to some whales several times a year or to every single grey whale left."

Naval exercises, involving US and Nato warships using active sonar, have "definitively caused or been associated with multiple stranding events of whales and other marine mammals around the world," dating to 1996, according to Earthjustice.

After 17 whales beached during a US Navy exercise off the Bahamas in 2000, marine autopsies found they had haemorrhaged in and around the ears. Sound conducting tissue was also damaged. The NMFS and Navy found the injuries were caused by "acoustic or impulse trauma, most likely" from MFA sonar.

Inevitably, the threat to whales is driven by US national security. Active sonar is used to hunt diesel-electric submarines, which can run very quietly and are favoured by many Asian nations [Indian ships using active sonar in the Andaman Sea may have killed 40 whales in January].

The NRDC and its allies would like the Navy to avoid sensitive habitats at specific times, use passive sonar to detect marine animals before exercises, and employ computer models to determine how salinity, ocean topography and temperature affect sonar impulses. Otherwise the Navy risked pushing whales and other endangered species towards extinction.