SEATTLE -- The

must take precautions -- including shutting down sonar use if marine mammals are spotted near training exercises -- when using the sound-wave technology or explosives off the Northwest coast,

says.

The Navy requested authorization for the training exercises under the Marine Mammal Protection Act because noise from mid-frequency sonar and explosives may affect the behavior of some animals or cause temporary hearing loss.

Environmentalists said NOAA's safety measures are ineffective because animals can be harmed outside of the monitoring zone and some marine mammals most vulnerable to sonar are extremely difficult to spot.

More than a dozen groups sent a letter last month urging NOAA to limit training exercises in the Olympic Coast National Marine Sanctuary, about 3,300 square miles of rich marine ecosystem off the Washington coast.

"Remarkably, not a single square inch of habitat has been put off limits to sonar use," said Michael Jasny, a senior policy analyst with the Natural Resources Defense Council. "That would be conservation management 101, and it's intensely disappointing that the sanctuary did not receive special treatment."

The Navy last month approved a plan to expand training and weapons testing in the sea and air in the

, the principal training ground for units based in Washington state. The area off the Northwest coast is used by about 32 species of marine mammals including whales, dolphins, seals, sea lions and the sea otter, as well as birds, fish and other animals.

The Navy's plan increases the number of training exercises and includes new weapons testing including guided missile submarines. Most of the exercises will take place 10,000 feet in the air, said Sheila Murray, the Navy's northwest environmental public affairs officer.

Jim Lecky, director of NOAA's Office of Protected Resources, said the activities are not new and have been occurring for decades without problems.

The agency believes the safety measures "are appropriate, and the level of risk that animals are exposed to are low," Lecky said, adding that most of the Navy's exercises are outside of the sanctuary.

NOAA said it does not expect Navy training exercises to result in serious injury or death to marine mammals.

Under NOAA's measures for the areas off Washington, Oregon, and northern California, the Navy must establish a safety zone around vessels that use sonar, shut down sonar use if marine mammals are seen within designated safety zones. It also is not allowed to detonate explosives when animals are detected within a certain distance.

Murray said the Navy worked closely with NOAA to develop the measures.

People have the misperception that marine mammals will be washing up on beaches, Murray said. "The Navy has been training here for well over 60 years, and we don't see that now."

The Navy's environmental review estimated that active sonar exposure will disrupt behavioral patterns of about 129,000 marine mammals each year, though none will be killed.

The safety measures "will reduce the number of animals affected but not reduce it to zero," said David Bain, a researcher in Seattle, who has studied the effect of noise on harbor seals, sea lions, killer whales and other mammals in Washington. "The best way is to work in areas where they don't hang out."

-- The Associated Press