Navy sonar unquestionably disturbs beaked whales, concludes a new analysis investigating how underwater sound affects these elusive deep-divers. The results, published online March 14 in PLoS ONE, suggest that the current noise levels deemed risky for beaked whales need to be lowered.
During sonar exercises at the U.S. Navy’s underwater test range in the Bahamas, beaked whales stopped their chirpy echolocations and fled the area, experiments employing a huge array of underwater microphones revealed. Other experiments that exposed tagged whales to increasing levels of sound found that at exposures of around 140 decibels, the animals stopped hunting for food and slowly swam toward the surface, heading north toward the only exit of the deepwater basin known as the Tongue of the Ocean. Current regulations rate underwater exposures of about 160 decibels as disturbing.
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