CLMI: How to Keep the Oceans Quiet
A world once filled with mostly marine and fish noises is transforming into one of mostly human noises ... and the marine life that lurks beneath can't live like that.
Aurora Ellingboe | a Learn4Life CLMI fellow
In 2020, when the pandemic decelerated international shipping, humpback whales returned home to the Glacier Bay in Alaska to spend the summer days feasting. They soon discovered what it was like to have peaceful waters filled with mostly marine noises. Normally, the sound of fishing vessels, commercial shipping, and cruise ships fill the bay.
When scientists found a trend across the world’s oceans, it appeared non-coincidental. In Vancouver waters, the pandemic cut down noise pollution by 50 percent from the few months before. Scientists attributed the phenomena to the reduction of local ferry traffic, cargo ships traveling slower, and cargo ships decreasing in size.
Whales of all types rely on sound to survive on a daily basis. Scientists suspected that a decrease in noise pollution could help endangered killer whales hunt Chinook salmon through the use of a technique called “echolocation” in what was once an increasingly suitable environment.
But, three years later, the pandemic years have been ever-changing, and noise pollution decibels are rising yet again. A world once filled with mostly marine noises is transforming into one of mostly human noises, and the marine life that lurks and floats beneath cannot hear one another. What are the consequences when marine life loses its hearing and is faced with deteriorating health, especially when fish populations are declining faster than they are rebounding?
What is “Ocean Noise?”
According to the National Ocean Service, ocean noise refers to …
[S]ounds made by human activities that can interfere with or obscure the ability of marine animals to hear natural sounds in the ocean.
Ocean noise varies from vessel traffic and individual ships and boats to oil and gas industry activities, military sonars, commercial sonars, military explosive devices, and construction.
The problem, however, is that regular, organic ocean noise is crucial. Clownfish, conceived on coral reefs, spend the first part of their lives drifting on the open ocean waters. Once the blind clownfish larvae grow large enough to swim against the ocean waves, they swim to their coral reef relying on the crackling, snapping sound of the corals – that's if the clownfish can hear them over human “ships, seismic surveys, air guns, pile drivers, dynamite fishing, drilling platforms, and speedboats.” But clownfish are not the only marine animals suffering from ocean noise.
Most ocean fish adapted to rely on sound to travel. Visual signs dissipate following tens of yards, while chemical signs vanish following hundreds of yards. Ocean organisms use sound because sound travels thousands of miles within the ocean. Dolphins refer to other dolphins using special names, toadfish like to hum, bearded sills trill, and whales sing. Sound influences zooplankton and jellyfish too.
Ocean life has since adapted to ocean noise by moving away from it, but not all show the same success with the task. Sometimes, marine life leaves altogether. A 2002 study showed that the installation of acoustic harassment in the ocean correlated with a decline of the killer whale species. On the other hand, some whales stop singing altogether when they hear human-made noises in the water.
The damage is physical too. Temporary sounds can cause chronic hearing injury. Fish can regrow cells necessary to hear, but marine mammals cannot. One of the loudest sources of noise in the sea is military sonar. Military sonar resulted in bleaching in some dolphin species, but it also caused brain hemorrhage and embolisms, killing several dolphins close to the source of the sound.
Ocean noise affects most to all of ocean life. Ocean noise interrupts marine organisms’ behavior, physiology, and reproduction, increasing risk mortality. Through use of sound, marine organisms can warn of danger, find food, sense their surroundings, communicate, attract mates, navigate, and avoid predation. Human behaviors are ultimately stealing from marine animals’ way of life. This unnatural disruption of marine life is called acoustic masking.
Solution: Underwater Noise Management
Human beings could reduce noise pollution in a handful of different ways. Most of these solutions are simple, but they do could require help from policymakers. In a recent first, the European Union created new rigorous standards to reduce ocean noise pollution – but, that’s up to the Member countries to implement individually ...
The new limits mean, that to be in tolerable status, no more than 20 percent of a given marine area, can be exposed to continuous underwater noise over a year Similarly, no more than 20 percent of a marine habitat can be exposed to impulsive noise over a given day, and no more than 10 percent over a year.
At the moment, there’s not much evidence that’s being done aggressively, even though it’s the first step of “its kind at a global level.” In the United States, there’s been very little legislative success of even awareness. Rep. Rick Larsen (D-WA) introduced a bill in the House in 2022 to establish programs to reduce the impacts of vessel traffic and underwater noise on marine mammals - but, there were barely 5 co-sponsors and the legislation was only introduced and has never went any further than the lower chamber of Congress.
According to the National Park Service, two ships traveling at a lower speed than one fast ship, produce less disturbing noise for whales. Even if the slower ships take longer to make a trip, they produce less cumulative sound exposure level (“CSEL”), the amount of noise a whale is exposed to in a day. Implementing speed regulations or policies can help reduce CSEL whales receive every day. Older propellers produce more “cavitation,” or the process whereby miniscule bubbles form around the blade, driving out a deafening screeching sound. The development and installation of new, quieter ship propellers and maintenance of clean, polished propellers and insulated engines are the simple and much popular solutions for reducing ocean noise; but cutting down a ship’s speed is the easiest solution to date. What are we waiting for?