Under the sea, human-made noise is threatening animals’ soundscapes and ecosystems

Imagine that you live in murky darkness, and sound is the primary sense by which you find dinner, avoid danger, and keep your offspring close. Perhaps you are a sperm whale relying on Morse-code like clicks to find your pod, or a dolphin who uses echolocation to evade sharks. Maybe you’re a cleaner shrimp that advertises its services to reef fish by clapping. Or a male plainfin midshipman who hums to attract a mate.

Storms, waves and wind are the natural soundscape playing in the background. But now there’s the constant roar of cargo vessels, the piercing ping of sonar travelling for dozens of kilometres, and the blasts from oil and gas exploration sounding off like gunshots echoing on top of each other.

Since whales and many marine animals use sound to see, this would be like being caught in the inescapable glare of a blinding spotlight – with no idea of its source.

For humans, that kind of noise spikes blood pressure, steals sleep, increases anxiety, and makes it near impossible to think straight. The European Environment Agency estimates that noise pollution contributes to 48,000 new cases of heart disease and 12,000 premature deaths each year. And the World Health Organization has declared the rising, incessant cacophony of the modern world to be a public health crisis – an environmental problem second only to air pollution in the harm it causes.

All that blasting, pounding and rumbling is damaging our ocean life as well. International studies suggest an ever-growing list of harms caused by human-generated noise: dolphins catch less prey, disoriented whales struggle to avoid ship strikes, turtles temporarily lose their hearing, muddled lobsters cannot right themselves. Even coral reefs and seagrass appear to degrade when exposed to noise.

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Scientists worry that noise is potentially damaging entire ecosystems, by changing the behaviour and harming the health of the inter-connected animals living there.

“This is the most pervasive and unregulated pollution in marine systems,” says Kieran Cox, a marine biologist at Simon Fraser University, who studies aquatic soundscapes.

At the current rate, noise emissions from global shipping will double roughly every decade, according to Scandinavian research published last year. Without intervention, the ocean will only get noisier as melting Arctic ice opens up shipping lanes, and deep sea mining projects expand.

The timing could not be worse. Our human clang and clamour is silencing a vulnerable ocean just as new technology has become available to help scientists hear and protect its diverse inhabitants.

If we listen, one message already comes through loud and clear: the humans need to keep it down. “If we don’t get a handle on noise pollution, many of these species may disappear,” says Karen Bakker, geography professor at the University of British Columbia, and the author of book, The Sounds of Life. “Even if we could figure out how to talk to them, there’d be no one left to talk to.”

Lindy Weilgart was decoding whale chatter at Cornell in 1993 when she heard about plans to place loudspeakers in the middle of the Monterey Bay National Marine Sanctuary, off the coast of Northern California. The US$35-million project, designed to study climate change, was being discussed enthusiastically at staff meetings; financed mainly by the United States military, nearly a dozen universities would participate and prominent names were involved.

The project involved blasting a low-frequency grinding sound for 20 minutes every four hours across the Pacific Ocean to a receiving microphone in New Zealand. Sound travels roughly four times faster in water than over land, and faster still in warm water; over many years, the research team would record how climate change was heating the sea.

At the time, Dr. Weilgart was a 32-year-old postdoc, without the international expertise she is known for today. She had just returned from a year travelling the Pacific with her then-husband and their two kids, a 10-month old and 5-year old. They were following the route charted by historic whaling maps to record the staccato clicks that families of sperm whales used to talk to each other. At the time, studying whale communication was well-established science; early research supporting the idea that underwater noise might be causing serious, inadvertent harm to those same whales had received much less attention.

“I couldn’t let it go,” Dr. Weilgart says. She thought about how, sometimes, to observe the whales in their natural environment, they would slip quietly into the water so they didn’t disturb the pod; even a slight splash from flippers would startle the large mammals. “I know how sensitive they are. How were they ever going to cope with this noise – every four hours?”

Speaking out, she says, “was not a good career move.” But Dr. Weilgart returned to Dalhousie University, unable to stay quiet. For a month, she sent faxes to environmental groups and journalists, and raised the issue in email discussions with marine biologists. The ensuing controversy led to media coverage, public outrage and a threatened lawsuit until the project was amended: The speaker was moved from the sanctuary and would only transmit sound for two years. Not a perfect win, but Dr. Weilgart decided it was good enough.

“Remember, they weren’t solving the effect of climate change, they were just measuring it,” she recalled this summer, sitting in her home in Herring Cove, N.S., recently home from presenting her latest paper on noise pollution at the United Nations.

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Today, Dr. Weilgart, 62, is the Senior Ocean Noise Expert and Policy Consultant with OceanCare, a non-profit conservation group based in Switzerland. But back then, she did not realize how prescient she was. A few years after the Monterey loudspeaker made headlines, naval ships using sonar off the coast of Greece and the Bahamas left a wake of whale beachings. The animals had hemorrhaged in their brains and hearts. Some were bleeding from their eyes. Dr. Weilgart says researchers believe the panicked animals suffered decompression sickness; the sound disrupted their dive patterns so they didn’t surface for air. The dramatic images of dying, stranded whales put noise pollution on the public’s radar.

“The issue with noise that sets it apart is the enormous potential scale of impact,” says Dr. Weilgart. “It travels so fast and so far. From plankton to whales, everything is impacted by noise.”

Some of that damage has already been done: A recent study by Calgary researchers found that if marine noise pollution had remained at pre-1998 levels, the southern resident killer whale population would be 30 per cent larger today.

Constantly expanding human industry – mainly from shipping, military sonar, and oil and gas exploration – has only made the ocean noisier. Over the last 50 years, the growing fleet of cargo vessels and oil tankers have led to a 32-fold increase in low-frequency marine noise, according to a 2021 paper published in the journal Science. The problem is more serious in high traffic areas, but underwater sound doesn’t stay local. A low-frequency active sonar, Dr. Weilgart says, can be heard at levels known to impact whales across 3.9 million square kilometres – an area roughly the size of India.

To detect oil and gas exploration under the sea floor, Dr. Weilgart explains, companies tow massive arrays of seismic air guns that fire off every ten seconds. The return echo is picked up by hydrophones, to determine what’s under the ocean floor. On land, handling a discharging air gun “can blow your arm off,” says Dr. Weilgart. A fish swimming too close would be ripped apart. For those farther away, one blast fades away just as another follows behind, leaving animals swimming in what scientists have called an “acoustic smog.”

“Try holding this conversation, if we had a mini-explosion going off nearby every 10 seconds,” she says.

The tragedy is that all this noise pollution is coming at a time when we have never been closer to understanding all the conversation that might be happening under the sea. A whale dictionary may not yet exist, Dr. Bakker writes, but scientists are diligently collecting the raw data to create one, and we now have computers smart enough to find patterns in the clicks and squeals of whale chatter that a human might search decades to find.

The work of bioacoustic scientists goes well beyond creating a Google translate for whale-speak. Their research is currently used to protect and restore vulnerable marine ecosystems – necessary for our survival as well – and mitigate human harm in the ocean.

“This is a listening exercise,” says Shane Gero, a marine biologist at Carleton University who has been studying sperm whales for nearly two decades. “We’re stopping to ask what’s important to the whales.”

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Dr. Gero collaborates with CETI, a non-profit research group using artificial intelligence to study whale communication. By sheer luck, this summer they were following a pod off the coast of Dominica when they filmed a rare birth. Drones flying overhead captured the whale family as they took turns supporting and meeting the newborn. The sound was recorded with a microphone underwater, capturing an unprecedented amount of material.

Observing whales isn’t easy: They often surface for 15 minutes, and dive to feed for another 50 minutes. Now the research team had observed an extraordinary moment, bringing them closer to understanding the complex social life of whales – before they, potentially, disappear.

This summer, CETI plans to leave hydrophones in the water permanently to passively record whale sound, compiling enough data to allow a computer algorithm to search for patterns in their communication. The project, says Dr. Gero, will also be able to quantify the human contribution to ocean noise. Bioacoustics is also being used to alert ships to the location of whales in real time in the Gulf of St. Lawrence.

While whales may be the most charismatic sound communicators in the ocean, they are far from the only ones. Science continues to reveal diverse and complex ways that non-human animals communicate in habitats we can’t easily study, and at frequencies we cannot hear. The sounds of sea creatures collected so far account for only a fraction of the ocean’s inhabitants.

Last year, scientists in Canada, the U.S. and Brazil created a digital website called FishSounds to collect recordings of the 1,000 species of fish now known to intentionally make noise to communicate. A growing number of open-access sound libraries are being used to study the effect of human-generated noise on vulnerable species, as well as assess the state of marine ecosystems by the diversity of their soundscapes.

Like a forest on land, a healthy reef is a bustling, chatty place. New research shows that even animals that may not actively make sound themselves still use noise to find safe, food-rich habitats. In a study published last October, Australian scientists used low-cost underwater microphones playing a healthy reef soundscape to successfully attract baby oysters to a restoration reef project.

In Barkley Sound, off the west coast of Vancouver Island, Dr. Cox is overseeing research into kelp clusters. His work shows that, like forests, kelp helps to dampen noise for sea life. But kelp is dying as the water warms, leaving the creatures of the sea even fewer places to hide from the pounding, rumbling, human-noise that torments them.

“We’ve got this data that’s showing us harm,” says Dr. Bakker. “We can detect the harm in real time. Now, we’re going to require a response.”

At a mooring in Lunenburg Harbour, Danielle Southcott and her husband, Julian, are readying their refurbished wooden schooner, Sea Change, for its first sail since they found the 52-foot boat, drying up on land, and made an offer.

Her grand ambitions, however, lie with a sailing vessel of her own design: a newly certified, 100-metre cargo ship that she hopes will someday carry goods around the world. The boat would be the first commercial shipping vessel to travel primarily by sail, augmented by a hydrogen-powered electric engine, producing zero emissions. It will also be relatively silent; even the blades of the propeller feather when not in use so they go with the water and not against it.

Ms. Southcott, and Veer, the shipbuilding company she founded and heads, will soon field contracts from shipyards to build it – and ideally, Veer’s first vessel will be carrying goods by 2025. Ms. Southcott says the company already has letters of intent from prominent retail companies interested in the positive branding a sailing cargo ship would deliver.

“I wanted to build the fastest, meanest container sailing ship I could make,” says Ms. Southcott. But she also envisions a fleet of quiet, zero-emission vessels that transform shipping. “The industry has an astronomical amount of inefficiencies that are not being addressed,” she says.

Ship design, sail technology and precise weather forecasting have helped reinvent sail power. “We did this up until the 1930s with no engines,” Ms. Southcott says, “but people have forgotten.”

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A sailing cargo ship may seem like a fringe idea, but Dr. Weilgart says adapting shipping vessels to use wind power is one of the innovations now presented regularly at international conferences to address ocean noise – the kind of outside-the-box thinking she hopes new rules of the sea will eventually require.

On the noise pollution front, Dr. Weilgart gives Canada full kudos. At the International Maritime Organization, she says Canada has pushed to update international shipping noise guidelines. The Port of Vancouver was the first to incentivize quieter ships by giving them substantial cuts in docking fees. The federal government is working on an Ocean Noise Strategy meant to co-ordinate a national response to address marine noise pollution. And in 2019, Transport Canada launched the $26-million Quiet Vessel Initiative to find research into promising technologies.

Meanwhile, researchers such as Dr. Cox have been mapping marine noise pollution around Canada’s coast to inform policy decisions about boat speed limits and routes through areas near whales and other vulnerable marine life.

Of course, Dr. Weilgart points out guidelines are only suggestions. “If we regulate it,” she argues, “the innovation will come.” Her latest paper, published by the UN Convention on the Conservation of Migratory Species of Wild Animals, argues that we don’t need to wait for more science showing harm when the evidence is overwhelming and proven remedies to reduce noise already exist.

Slowing ships down, even marginally, significantly reduces the noise they make, and, as an added bonus, the fuel they expend. A voluntary slowdown program has been running in the Haro Strait and Boundary Pass on Canada’s west coast since 2017. By encouraging ship operators to slow speeds or avoid key habitats, underwater noise in the foraging area of the southern resident killer whale has been reduced up to 55 per cent.

Improving hull and propeller design, as well as proper maintenance and cleaning, would also reduce noise, Dr. Weilgart writes in her paper. Targeting the noisiest vessels would also make a significant difference – research shows that about 10 per cent of cargo ships account for more than 50 per cent of the acoustical footprint.

A shift to green energy, Dr. Weilgart adds, would reduce the need to drill for fossil fuels. But in the meantime, oil and gas companies could also do less harm by replacing air guns with marine vibroseis, which uses vibration to analyze the ocean floor, and creates sound waves at a lower intensity.

For those of us back on land, Dr. Weilgart suggests that waiting a little longer for our online deliveries would also be an individual act of whale-directed kindness. Perhaps one day, she suggests, we’ll able to expressly choose to have consumer goods shipped with quieter and cleaner ocean considerations.

From her deck at Herring Cove, Dr. Weilgart can watch the stream of cargo ships lumbering past, on their way into the port of Halifax. Sometimes, she sees whales – a visible sign of the collision between their world and ours. “If everything else were perfect, marine animals could maybe cope with noise fine,” she says. “But they are dealing with a gazillion other things. How much more do you think they can handle?”

It’s also worth remembering, says Dr. Weilgart, that the fate of humanity depends on healthy oceans. “We pretend we are self-reliant,” she says. “But every second breath we take comes from the ocean.”

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Following whales in the Caribbean a week after the birth they witnessed, Dr. Gero and his CETI colleagues have yet to see the baby sperm whale again. They are holding off on a name for now, their joy at the new arrival muted by worry: One in three sperm whale calves don’t live past their first year.

Even when their families don’t inhabit busy water highways, the ocean is a risky place for newborns. Sperm whales are also endangered by marine plastic, entanglements in fishing gear, ship strikes, and noise pollution – the clattering echo, Dr. Gero says, of all our human excess.

“We’ve been bad neighbours,” he says. “We’re making that baby’s life a lot harder, simply by ignoring our impact on the ocean.”

Ultimately, a quieter ocean means a better, rest-easy world for humans, fish and baby sperm whales alike.

“She’s out there now,” Dr. Gero says, “swimming around in the face of predators and nets and boats and noise. So what are we going do about it?”

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