Unfortunately for many whales, dolphins and other marine life, the use of underwater sonar (short for “sound navigation and ranging”) can lead to injury and even death. Sonar systems, first developed by the U.S. Navy to detect enemy submarines, generate slow-rolling sound waves that top out at around 235 decibels; the world’s loudest rock bands top out at only 130. These sound waves can travel for hundreds of miles under water and can retain an intensity of 140 decibels as far as 300 miles from their source. While little is known about any direct physiological effects of sonar waves on marine species, evidence shows that whales will swim hundreds of miles, rapidly change their depth—sometimes leading to bleeding from the eyes and ears—and even beach themselves to get away from the sounds of sonar.

In 2003, the National Resources Defense Council (NRDC) spearheaded a successful lawsuit against the Navy to restrict the use of low-frequency sonar off the coast of California. Two years later, a coalition of green groups led by NRDC asked the federal courts to also restrict testing of more intense, harmful and far ranging mid-frequency types of sonar off Southern California’s coastline. The groups cited Navy documents which estimated that such testing would kill some 170,000 marine mammals and cause permanent injury to more than 500 whales, not to mention temporary deafness for at least 8,000 others. Coalition lawyers argued that the Navy’s testing was in violation of the National Environmental Policy Act, the Marine Mammal Protection Act and the Endangered Species Act. Two lower courts upheld NRDC’s claims, but the Supreme Court ruled that the Navy should be allowed to continue the use of some mid-frequency sonar testing for the sake of national security.

Environmental groups are still lobbying the government to curtail testing, at least during peacetime, or to at least ramp up testing gradually to give marine wildlife a better chance to flee affected areas. “The U.S. Navy could use a number of proven methods to avoid harming whales when testing mid-frequency sonar,” reports the International Fund for Animal Welfare (IFAW)’s Fred O’Regan. “Protecting whales and preserving national security are not mutually exclusive. For more information, visit nrdc.org.