Do you hear what they hear?

As humans, we rely heavily on our five senses – hearing, touch, smell, taste, and above all sight. Ours is a primarily visual world; light, dark, colors, words, signals, faces… all of this input informs every moment of our day. Language is how we communicate but sight is how we remember each moment and experience our world.

How far can sound travel in the ocean?It’s very different underwater. One of my favorite things to do underwater is close my eyes and listen to the snaps, crackles, groans, and pops of all the creatures chattering back and forth. Underwater, hearing is like sight on the surface. Visibility though the water on a good day is 150 feet – for us and for the animals that live underwater. So although many underwater creatures have great eyesight, mainly they rely on sound. Sound is their sight, how they sense the world, how they communicate, how they get information about their environment. Water is a bafflingly efficient conductor of sound; some of these sound signals can even travel thousands of miles underwater, delivering important signals across vast oceans.

In the middle of the 20th century, sound levels in the ocean began to change. Major shipping of goods began to spur ship movement around the globe. Companies began exploring the ocean floor for resources and mapping. Ship traffic, seismic exploration, and sonar noises began to ramp up the volume in the world’s oceans.

Imagine you are going about your business all day with a persistent flashing light or large visual disturbance, and you have no way to get away from it. All this sound causes a cacophony of noise in the ocean, disturbing navigation patterns of social animals, and causing mass strandings and disrupting their natural behaviors, even going so far as to cause bleeding in the ears of marine mammals that rely on their hearing for coordination of movement with their pod to feed or migrate. This can lead to elevated stress level in animals which can affect no only their movements, but their reproductive patterns (who wants to breed when their stressed out?), and feeding behavior (stress can cause loss of appetite in most species). This is what it is to live in the ocean now, in the age of 60,000 container ships motoring across the water at any given moment, seismic explosions that reflect loud noises off the seafloor searching for oil and gas deposits, and naval vessels deploying sonar to detect targets even when no threat is imminent.

The good news is that noise pollution isn’t like other pollutions. Once the noise stops, it’s gone. There is no filtration that needs to happen, no lingering after-affects, no cleanups, no oil booms, nothing. And reduction in noise has already been shown to lower stress levels in certain species of whales. A long-term study of east coast Right Whale stress hormones revealed that in the days following the 9/11 attacks when many non-essential marine traffic was halted security measures, stress hormones in these whales dropped significantly. Why? Because the noise level dropped for a few days. Once the travel ban was lifted, stress levels returned to normal.

Great, another one of those massive problems that need fixing, what can I do? Lots, actually. Simple things like buying products made locally that don’t need to be shipped overseas. If you own a boat, keep the hull and propeller clean and your engine space well insulated, as well as travel at efficient speeds that will both limit fuel consumption and reduce propeller cavitation noise and turn off your depth sounder when you don’t need it. More broadly, encourage ship building companies to design quieter engines and hulls, as well as ask shipping companies to follow lower speed limits to reduce engine noise in less efficient vessels. Contact your congressperson to ask them to propose or support legislation to reduce off-shore drilling and exploration, and encourage more responsible actions from oil and gas companies. Encourage the use of passive sonar monitoring in place of active sonar testing and promote the development and use of potentially less disruptive marine vibroseis to replace seismic seafloor mapping and exploration where appropriate.

Most importantly, educate yourself and others about this problem that many are still unaware of. The most important thing you can do is spread the word. (Be sure to listen to the clips in each of the ocean noise examples to get a taste of what the underwater world can sound like every day to some animals). And remember, no one in the ocean is deaf or silent. Many marine species are blind by design, but not one entity cannot hear the symphony of sounds that we – as a species on this shared planet – create.

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