One morning, on a beach in the Bahamas, whale researcher Ken Balcomb discovered a stranded whale. With the help of assistants, he tried to push it out into deeper water, but it came back to shore. Then the researchers discovered another whale down the shore, and another. That day, 17 beaked whales—a species that normally lives in very deep water—showed up on beaches around the Bahamas, and died.
Balcomb wanted to find out why. When he sent specimens of the whales to a lab, scans showed evidence of hemorrhaging around the brain, and blood around the ears. The problem, he eventually learned, was extreme noise—sonar tests from Navy warships had driven the whales to try to get out of the water.
The story of the mass beaching, one of many around the world, is part of a new documentary called Sonic Sea, which explains how human sound is transforming life in the oceans. Over the last half century, as cargo shipping and deep sea oil exploration has increased, background noise in the ocean has doubled roughly every decade.
A single massive container ship—four football fields long—can put 190 decibels of sound energy in the water, louder than the sound next to a speaker at a rock concert. At any given time, there are 60,000 commercial ships in the ocean. "The sound is completely inescapable," says Michael Jasny, director of the Marine Mammal Protection Project at the Natural Resources Defense Council, one of the producers of the documentary.
"The most important thing to understand in thinking about noise in the ocean is that the ocean is a world of sound," Jasny says. "Marine mammals, fish, and other marine species have evolved to depend on hearing as their primary sense. There's a good reason for this—a mature blue whale can scarcely see its own flukes [tail] in the water, and yet blue whales can communicate with one another across entire ocean basins."
While light can't travel far through ocean water, sound can: In one experiment, researchers who made a sound in the Indian Ocean were able to detect it in both Washington State and in the Atlantic Ocean. In another study, researchers who were listening to whale sounds in the middle of the Atlantic Ocean couldn't hear the whales anymore when noise started from oil and gas drilling in West Africa.
"The sea is being industrialized, and that is having a sweeping impact on the acoustic world that whales and other marine life have to thrive in," Jasny says.
The constant wall of sound impacts how marine organisms search for food, communicate, navigate through the ocean, and almost every other aspect of life. Right whales, an endangered species living in the North Atlantic, can no longer hear each other as much as 80% of the time. It's a relatively recent change; since some whales can live 200 years, some of them grew up in a quiet ocean.
The good news: Better technology can dramatically reduce the noise. Oil and gas drillers, for example, usually use airguns with massive dynamite-like explosions to map the sea floor. But it's possible to use marine vibroseis, a technology that's thousands of times less invasive, instead. Some shipping companies are beginning to use technology for quieter ships. In Washington, ferries are now using quieter propellers (which, what do you know, also happen to be more efficient and save fuel). Ships can also reduce noise just by slowing down. Since it's typical to wait three days at a port after arrival, some experts argue that there's no reason to go faster.
"This is a problem that can be solved," Jasny says. "The only good thing about ocean noise pollution is that noise disappears once you stop making it—it doesn't linger behind very long in the environment like other pervasive pollutants do."
In 2014, the International Maritime Organization adopted voluntary guidelines for quieter ships. "Now the trick is to get those guidelines implemented—to get shipping lines and to get ports to take actions to reduce noise," he says.
Sonic Sea will premiere on the Discovery Channel on May 19.