Navy subs routinely use sonar - the underwater version of radar - to navigate and to detect potential threats. But the powerful sounds harm whales and dolphins. In fact, some sonar systems can generate 235 decibels. In air, that's as loud as a Shuttle launch. Enough examples of that harm abound to suggest a better balance must be found between the military's need to use sonar and the need to protect marine life.
Last week, more than 60 dolphins beached themselves in the Florida Keys, perhaps because of a nearby Navy sub training exercise. More than 20 have died. Last month, 37 whales of three different species died after beaching themselves in North Carolina. Though Navy officials maintain not enough conclusive evidence links sonar to that unusual mass stranding, they say ships were using sonar in nearby waters at that time. And they have acknowledged that sonar was responsible for a beaching of whales in the Bahamas in 2000.
Just how a sonar signal can disorient or harm a whale or dolphin still isn't exactly clear, but mounting evidence indicates that mid- and low- frequency range sonar can cause them to beach, surface too quickly, or behave in other unusual ways. The International Whaling Commission and other environmental and scientific groups have published reports supporting the possibility that sonar has such effects.
The Navy's training exercises (which account for about 90 percent of sonar use) once were mostly carried out far away from coastlines, and thus not near dense whale populations. But the terrorist threat, which includes the possibility of an enemy attack on a port, and the advent of so-called "silent" subs - which are best detected with sonar and could be used by a potential enemy - have prompted the Navy to move some exercises closer to shore.
Last week, the Bush administration issued a statement opposing international efforts to curb sonar use. That, however, shouldn't rule out unilateral steps in which the Navy could restrict sonar use in training exercises. It should also work voluntarily with other nations along those lines.
As the world's largest funder of ocean research, the Navy has an opportunity to be a better environmental steward. It can help discover more about how sonar affects marine life, and look for sensible solutions.
Researchers at Duke University, for instance, are crafting a system to more precisely predict where whales are located. That technology could put some distance between Navy ships and these majestic animals.