Is it true that military sonar exercises actually kill marine wildlife?
-- John Slocum, Newport, RI

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 topping 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.

These rolling walls of noise are no doubt too much for some marine wildlife. 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 (sometime leading to bleeding from the eyes and ears), and even beach themselves to get away from the sounds of sonar.

In January 2005, 34 whales of three different species became stranded and died along North Carolina’s Outer Banks during nearby offshore Navy sonar training. Other sad examples around the coast of the U.S. and elsewhere abound, notably in recent years with more sonar testing going on than ever before. According to the nonprofit Natural Resources Defense Council (NRDC), which has campaigned vigorously to ban use of the technology in waters rich in marine wildlife, recent cases of whale strandings likely represent a small fraction of sonar’s toll, given that severely injured animals rarely make it to shore.

In 2003, 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 and including the International Fund for Animal Welfare (IFAW), the League for Coastal Protection, Cetacean Society International, and Ocean Futures Society upped the ante, asking the federal courts to also restrict testing of more intense, harmful and far ranging mid-frequency types of sonar off Southern California’s coastline.

In filing their brief, 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. “The decision places marine mammals at greater risk of serious and needless harm,” says NRDC’s Joel Reynolds.

[link to www.scientificamerican.com]