Wildlife

Sonar Can Literally Scare Whales to Death, Study Finds

Naval sonar has been linked to mass strandings of otherwise-healthy whales for nearly two decades, but the precise mechanisms of how it affects whales has eluded scientists. Now, researchers have explained key details of how this disruptive signal triggers behavior in some whales that ends in death.

Previously, necropsies of beaked whales from multiple stranding incidents found nitrogen bubbles in their body tissues, a hallmark of decompression sickness, or "the bends." This dangerous condition also affects scuba divers when they rise too rapidly from deep water; it can cause pain, paralysis and even death.

Whales are adapted for deep-sea diving, and beaked whales are the record-holders for the longest and deepest dives. But the new research explains how sonar in certain frequencies disorients and terrifies some beaked whales so much that the experience overrides an important adaptation for deep diving: a slower heartbeat. Extreme fear accelerates a whale's heart rate, which can lead to decompression sickness; the intense pain of this condition incapacitates the whales, so they strand on beaches and eventually die.