The sonar threat.

Byline: The Register-Guard

It's becoming increasingly apparent that submarine-detect- ing sonar systems can be lethal to whales, and the U.S. Navy should make whatever adjustments are necessary to protect marine mammals.

The linkage between whales and sonar isn't hard to figure. Marine mammals depend on sound to navigate, find food, locate their mates, identify predators and communicate. Flooding their ocean habitat with unnatural, high-intensity sound unavoidably affects them. Anyone with a house, a teenager and a stereo system should understand the dynamics.

A scientific study published last year determined that whales and other marine mammals can be killed or harmed by sonar. It theorized that the animals can become frightened by the man-made sound and surface too quickly, causing nitrogen in the blood to gassify, which can cause internal bleeding.

Four environmental groups recently sent a letter to Navy Secretary Gordon England, citing numerous instances in which whales have beached themselves during nearby Navy maneuvers - often hemorr- haging blood through their ears and eyes.

The groups - the Humane Society of the United States, the Natural Resources Defense Council, the Ocean Futures Society and the International Fund for Human Welfare - emphasized that they recognized the importance of sonar to national security. But they rightly pointed out that the military should be able to carry out its vital mission, while at the same time taking care to observe environmental laws and to protect marine wildlife.

The Navy can do several obvious things to limit the damage to whales caused by sonar - especially in a post-Cold War environment when our admirals aren't living in fear that a Soviet nuclear submarine will suddenly surface off U.S. waters and flatten San Diego.

The Navy should start by not training or testing in those easily identifiable regions of the ocean attractive to concentrations of marine mammal species known to be sensitive to sonar systems. Scientists also recommend that the Navy establish safety zones around sonar-trans- mission vessels and, perhaps most importantly, reduce the strength of sonar signals.

The environmental groups contacted the Navy after a recent incident in which 200 melon-headed whales, a species that usually stays in deep water, herded together off the coast of Hanalei Bay in Hawaii. It turned out that the Navy had been using sonar in nearby exercises at the time.

Fortunately, local boaters kept vigil over the whales and herded them back to sea. Only one whale beached itself and died.

The Navy disputes claims that sonar was involved in incident, but the technology has been implicated in numerous strandings around the world. For example, investigators for the National Marine Fisheries Service concluded that Navy ships testing sonar in the Bahamas probably caused mass strandings of whales and dolphins several years ago.

In their letter, the environmental groups threatened legal action against the Navy. But it shouldn't take the threat of litigation to make the U.S. Navy fine-tune its sonar program to protect whales and other sensitive marine mammals.