When more than a dozen healthy whales and dolphins beached themselves near the Bahamas in March 2000, scientists investigating the event concluded that intense underwater noise or explosions were to blame. Six beached whales in the group ultimately died, exhibiting signs of trauma to organs associated with hearing, sound production, and air intake. One researcher said the animals that died appear to have experienced the equivalent of a terrible headache - bad enough to send a human to the hospital. The stranding occurred in the same area where the U.S. Navy was testing sonar systems designed to detect submarines operated by unfriendly nations. While it's too soon to tell whether the Navy's testing caused the noise that harmed the animals, the incident adds to the growing concerns of many scientists and environmentalists about the effects of increasing amounts of noise in the oceans.

This human-generated noise is coming from many different sources, including commercial enterprises (such as shipping and hydrocarbon exploration and production), military operations, and research programs conducted by the Navy and academic scientists. And evidence is mounting that some of this noise could interfere with breeding, feeding, migration, and other life-sustaining functions of marine mammals that rely on low-frequency sounds.

The Navy's research on ocean acoustics is already under intense scrutiny. Much of the other scientific research that uses sound in the oceans also falls under rigorous regulation. But while these experiments do contribute to ocean noise, they create only a small fraction of the sounds that could adversely affect marine mammals. Meanwhile, the much more frequent and potentially damaging sounds associated with commercial and military operations - and even whale-watching boats - remain unregulated.

It's time for the government to consider more consistent policies and laws to protect marine mammals from all types of harmful noise. A recent report from the National Research Council concluded that Congress should consider the regulation of sounds - regardless of their source - that are likely to disrupt behaviors critical to the survival of marine mammals. For example, the noise generated by oil drilling has been shown to cause gray whales to alter their swimming patterns. If this forces the whales to migrate closer to shore, making them more vulnerable to predators such as killer whales, then oil activities could have a significant impact on gray whale populations. The government should work with scientists to identify all sources of human-generated noise that, because of intensity, duration, or proximity to marine mammals, could be seriously damaging or life-threatening.

Any new regulations need to be consistent and fair. Under current law, for example, a marine scientist would need to get a federal permit to study the way a whale responds to the sounds of prerecorded ship noise. Because there is so much concern about potential harm to whales, these permits are hard to obtain and researchers are subject to a lengthy review process. But when commercial operators, or even other scientists, actually run ships producing exactly the same sounds in the same location, they do not need research permits.

Unfortunately, few data are available to help regulators determine which types of noise are the most dangerous. Research conducted in the past has been narrowly focused on obtaining specific information about the short-term effects of a single type of sound on a few species. A much more concerted effort is needed, involving biologists, acousticians, engineers, and statisticians, to conduct systematic studies that focus on learning more about the basic hearing capabilities of marine mammals, especially large whales, and how these animals use and respond to different kinds of sound.

There is no doubt that existing policies regarding marine mammals and sound in the ocean are well-intentioned, but they are wildly inconsistent. Ship-borne ocean commerce and national defense programs are so important to our nation that we are unlikely to want to inhibit them substantially. With that in mind, we must decide how far our society is willing to go to protect marine mammals from human-generated noise. The government should then make sure that the ensuing regulations are both fair and effective.