IT’S time to find out once and for all if noise pollution in the oceans is really harming whales and dolphins, a prestigious American scientific panel says.
Concerns that ships and underwater sonar equipment are deafening marine mammals have affected military exercises, and are beginning to impede scientific research. A report last week by the US National Research Council recommends that a single federal agency should be charged with tackling the problem.
People have long been worried that the cacophony produced by ships and sonar might confuse animals that use sound to communicate and navigate. The report says that while extremely loud noise can damage animals’ ears, there is a dearth of information on whether the ocean is actually getting noisier. The effect of a larger number of boats could be offset by quieter engines.
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There is “at least an indirect causal relationship” between military exercises and fatal beachings of beaked whales, the panel found. But the secrecy surrounding military exercises and the fact that no one tracked the whales during the sound exposure means no one knows exactly how the sonar might cause whales to beach. Beachings have happened when the US Navy has used its mid-frequency sonar, which operates between 1 and 10 kilohertz. Seismic surveys that fire loud blasts of sound at the ocean bottom, and the Navy’s new low-frequency active sonar (100 hertz to 1 kilohertz) which tracks submarines over larger distances, have also raised concerns.
But the law is struggling to keep up. For example, Peter Tyack at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts has developed a high-frequency “whale-finder” sonar that operates outside the hearing range of baleen whales. But last month, a court blocked Tyack’s permit to carry out tests with the equipment after environmentalists complained that his research into sonar, including the whale-finder, could be harming whales.
Yet Tyack’s sonar is designed to protect whales by checking whether any are nearby before sounding using lower-frequency noise begins. It also uses the same frequency as the unregulated fish-finding sonars used by fishing boats. “To regulate one and not the other makes no sense,” he says.
“A federal body should help avoid this,” says the chair of the committee, George Frisk, an acoustic engineer at WHOI. Because the oceans are a common resource, international regulations would be the best way to tackle the problem in the long term, he says.