They said the Navy has 14 training exercises planned off the coast of southern California in areas that are rich in sea life, including several species of whales.

Coastal Commission member Sara Wan told reporters there is growing scientific evidence linking sonar sound waves to whale strandings and deaths.

"In a whole variety of ways, it can actually cause them to die, and we have a lot of evidence of that in strandings," she said in a news conference on a cliff overlooking the Pacific Ocean.

The Natural Resources Defense Council, or NRDC, says that the problem is that the military's underwater sonar is so loud, the equivalent of 215 decibels or the noise produced by a fighter jet at takeoff. Whales who stranded themselves after sonar exercises have been found to have internal bleeding around their brains and ears.

The NRDC says that sonar use has been associated with mass strandings.

The coastal commission has said the Navy must take steps to look for whales, avoid using sonar when they are spotted nearby and use only low power sonar tests during times of low visibility when whales may be nearby but unseen.

The Navy has said the California agency did not have authority to impose the safeguards and that it already has measures to protect sea mammals from sonar.

The Pentagon in January exempted the Navy for two years from a law protecting marine mammals so that it could continue training exercises.

The NRDC said it has filed four other lawsuits against Navy sonar training exercises and has won three.