U.S. Navy sonar 'danger' to whales

The sonar uses the same frequency humpbacks use in their communication

WASHINGTON -- The U.S. Navy has been given the go ahead to use a powerful low-frequency sonar system to help it detect enemy submarines, a move environmentalists say will lead to increased marine mammal deaths.

The Commerce Department's National Marine Fisheries Services paved the way for the U.S. Navy to use the system after granting the Navy a five-year exemption from the Marine Mammal Protection Act.

The Navy says the $300 million (£191 million) system, called the Surveillance Towed Array Sensor System, or Surtass LFA, is important to national security because other nations such as Russia, Germany and China are developing super-quiet submarines to avoid traditional detection.

The National Marine Fisheries Service (NMFS) said the system would not cause serious damage to marine life. It said in a statement: "Marine mammals are unlikely to be injured by the sonar activities and ... the sonar will have no more than a negligible impact on marine mammal species and stocks."

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But environmentalists say the system will "harass" marine mammals and in particular endanger whales as they are susceptible to sonar interference. The mammals rely on sound for communication, feeding, mating and migration.

Michael Jasny, a senior policy analyst for the U.S. Natural Resources Defense Council, told CNN: "The National Marine Fisheries Service is painting around the edges of a very ugly picture. The Navy has been given the green light to deploy the system worldwide, and NMFS is just whistling in the dark about the impacts the use of this sonar will have.

"There is growing evidence that intense sounds impact marine mammals in a number of ways such as increased whale strandings, temporary and permanent deafness and changes in whale breeding behaviours."

The intense low-frequency sonar can travel several hundred miles and the transmissions are on the same frequency used for communication by many large whales, including humpbacks.

Each of the sonar's 18 speakers transmits signals as loud as 215 decibels, equivalent underwater to standing next to a twin-engine F-15 fighter jet at takeoff, the Navy says. The speakers will sweep 80 percent of the world's oceans.

Environmentalists argue that with the convergence of sound waves from each of the speakers, the intense effects of the system would reach farther, as if the signals were 235 decibels.

Environmentalists fear the sonar will cause whales to beach themselves

Some biologists believe whales are irritated by sounds louder than 110 decibels and that a whale's eardrums could explode at 180 decibels.

Fisheries officials outlined protective measures calling for Navy personnel to visually scan for marine mammals and sea turtles and to shut down the sonar whenever they are detected. Detection is expected to be almost 100 percent effective from a distance of 1.1 nautical miles away.

The Navy says it will restrict the sonar's routine use to at least 12 nautical miles away from coastline and outside biologically important areas.

"The decision is far too broad to provide any meaningful protection for whales, dolphins and other marine life," Jasny said.

Environmentalists' fears are partly based on the Navy's deployment of a powerful mid-range sonar in March 2000 during a submarine detection exercise in the deep water canyons of the Bahamas.

At least 16 whales and two dolphins beached themselves on the islands of Abaco, Grand Bahama and North Eleuthera within hours, The Associated Press said.

Scientists found haemorrhaging around the brain and ear bones -- injuries consistent with exposure to loud sounds -- among eight dead whales.

Twelve Cuvier beaked whales beached themselves in 1996 in Greece during NATO exercises using a similar low-frequency sonar, but the whales decomposed before scientists could investigate.