The oceans are not a silent world, but dynamic, living symphonies of sound. In water, sound travels five times faster, and many times farther than it does in air.
The Sonic Sea
Whales, dolphins, porpoises, and other marine mammals have evolved to take advantage of this perfect sonic medium. Just as we rely on sight to survive, they depend on sound to hunt for food, find mates, and detect predators.
Over the last fifty years, our increasing ocean presence has drastically transformed the acoustic environment of these majestic creatures. Undersea noise pollution is invisible but it is damaging the web of ocean life.
Three Major Causes of Ocean Noise
The leading contributors to ocean noise come from commercial, industrial, and military sources: Shipping, Seismic, and Sonar.
At any given time, there are up to sixty thousand commercial ships traversing our seas worldwide. Cavitation from propellers and the rumble of engines reverberate through every corner of the ocean.
The incessant and increasing cacophony masks whales’ ability to hear and be heard, hindering their ability to prosper and ultimately to survive.
To detect oil and gas deposits beneath the ocean floor, the petrochemical industry uses seismic airguns, the modern form of exploratory dynamite. Ships tow arrays of these guns, discharging extremely intense pulses of sound toward the sea floor.
During seismic surveys, acoustic explosions continue for days or weeks on end. The blasts disrupt critical behavior and communication among whales and can have massive impacts on fish populations.
Sonar is the principal submarine detection system used by the U.S. Navy and other navies of the world. To detect targets, naval warships generate extremely loud waves of sound that sweep the ocean.
Military sonar acts as an enormous predator. When exposed, some whales go silent, stop foraging, and abandon their habitat. Repeated exposure can harm entire populations of animals, and has led to mass whale strandings from the Canary Islands and the Caribbean to Japan.