The Decibel - Whales, extinction and the sounds of underwater noise pollution

Episode Date: November 3, 2025

North Atlantic right whales are nearing extinction, with fewer than 400 left in the world. We know what is killing them: getting hit by shipping boats, entangled in fishing lines and the impacts of climate change — which is changing the location of their food sources. But now, researchers think that human-made noise in the ocean may be having an effect too.Jenn Thornhill Verma is an environmental journalist who has been reporting on the plight of the North Atlantic right whales as part of her Entangled series for The Globe and Mail, in partnership with the Pulitzer Center’s Ocean Reporting Network. She explains how scientists are starting to understand how these whales communicate and how loud noises we’re making may be driving them closer to extinction.Underwater animal and environmental sounds courtesy of NOAA (National Oceanic and Atmospheric Administration). Passive Acoustics Group. 2021. Stfr_Multisound_NOAA_PAGroup_01. https://www.fisheries.noaa.gov/national/science-data/sounds-oceanQuestions? Comments? Ideas? Email us at [e-mail] Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Hi, Jen. Thanks so much for coming on the show. Hi, Cheryl. Thanks for having me. So, Jen, you're an environmental journalist, and we've got a piece of tape here from one of your reporting trips. Let's take a listen. This is late March of earlier this year. I'm on a research survey vessel. They're surveying North Atlantic right wells off the tip of Cape Cod in Massachusetts. So we're hearing a walkie-talkie exchange between one of the researchers that's outside on the flybridge observing the whales and the other that's in the wheelhouse inside documenting what they're seeing. We've only just started the survey and boom our first sighting of the day. And it's my first sighting. It happens to be a mother and her calf. Come back, please. Did you say mom cat? I come to learn later they're able to ID that this is not

And she's a 31-year-old adult female and really a seasoned mother because this happens to be her fifth calf. Copy that. Yeah. So let's start getting close to this animal. So just slowly there are about 150 meters away. We're moving on. So you're on this trip as part of a project you've done for the globe in partnership with the Pulitzer Center's Ocean Reporting Network about these whales. How did you feel when this was happening?

Yeah, I mean, not only was it my first North Atlantic right well sighting, and keep in mind, I had been months into this investigation for the Entangled series for the Globe. But, you know, I'm a mother to three little ones. So I think, for starters, that struck me as recognizable, this kind of synchronized movement between the mother and calf. But what also made it emotional for me at that time was every sighting of a North Atlantic Right Well and a calf is a victory because, for so long. I mean, these whales have been dying faster than they can reproduce. And the fact that

they've already made it here to these feeding grounds in Cape Cod Bay, where they have relative safety, is a big marker of success because they've had to, you know, go through so many different risks just to get here. And they happened to be the first mother calf pair spotted in the 2025 calving season. And they were the first documented to reach the Cape Cod feeding grounds. Wow, that sounds really special. I didn't hear the whales in the clip. Did the whales make noise when they were at the surface? Not that I could hear. I mean, you could certainly see that they came up to the surface to breathe and they relatively stay at the surface. But no, I mean, you really can't hear anything from the whales above the natural sounds in the environment. You can hear in the clip this

low engine rumble. So that's what I'm hearing. And I think, you know, that runs in sharp contrast to what we would hear underneath the water. So what does the ocean sound like under the water? I think many people might think that it's quiet, and I don't doubt that some parts of it are like the poles, but there's lots of natural sounds in the marine environment. You've got this everyday chitter-chatter between species that happens at different frequencies. And then the... there's the natural sounds of things like rain, thunderstorms, storms that see, even, you know, earthquakes. And in winter sounds of ice.

Okay, so it's really noisy down there. Is that a problem for the whales when they want to talk to each other? With natural sounds, which isn't noise to them, no, but the real problem is that we've seen a contribution of human-made or man-made noise that is a problem for the whales at the same frequency that they're communicating. And for a whale that's already in decline, it's putting further stress and it could contribute to their path toward extinction. The struggle for North Atlantic right whales to hear one another is an indicator of something greater at play. And the same noise that's drowning out whale calls is disrupting the fish we eat and the ecosystems that protect our coastlines. And so the question is, can we turn down the volume on an ocean we're making too loud or too polluted with man-made noise for life? to thrive. Okay, Jen, I'm going to pass the mic off to you for this episode. So I'm Cheryl Sutherland. And I'm Jen Thorne Hill Verma, and this is The Decibel from the Globe and Mail.

North Atlantic Great Wells, they're not as well known as other species like humpbacks or orcas, and if you do know them, you probably only know them because they've encountered tragedy. I had a chance to go out on the water, on Cape Cod Bay, and talk to Mark Baumgartner. He's a senior scientist, biologist at the Woods Hole Oceanographic Institution. And when we joined him on a research boat in late March, he talked about how people just generally don't think about this species. Keep reminding people, hey, there are right whales out there. One of the things that right wells suffer from is out of sight out of mind. Most people on land have no idea what a right It looks like they don't hear anything about them.

It's just a constant sort of reminder. These animals are out there. There aren't very many of them, and they're really in danger. The reason researchers know so much about this population, and it's quite unique, is that they follow their life history by taking photographs, they take genetic samples, and the whales are tracked in something called the North Atlantic Rightwell Catalog that's maintained by the New England Aquarium. And there, the whales, some 833 have been documented overall. And then the current population at about 384, they all have ID numbers and names.

One of the interesting things about North Atlantic right wells is that they have these white colossities or rough patches of skin that is like a whale's unique fingerprint. And in the case of Nosset, she has a colossity that looks like a lighthouse. So she's named after Nosset Lighthouse on Cape Cod. The other way in which researchers identify these whales is unfortunately through scarring. So if they've been through entanglements, for example, or they have propeller wounds or scars, those also can be telltale indicators that you're looking at a particular whale. And Nosset, we mentioned when we see her, it's with her fifth cat. We know, for example, that only two of the four previous calves have been seen in recent years,

and that's also really telling that although you have a calf like Nasset, who's a seasoned mother, she continues against all odds to reproduce, you are seeing that the survivability, unfortunately, of the calves is quite poor. The North Atlantic Great Well is a species at risk in Canada. that's endangered in the United States. And what that means is that they've reached a threshold in their population where any unnatural death is going to contribute to that species decline. And there's different categories that researchers use

to be able to assess how healthy a population is. And, you know, endangered, this is one where you don't want to be at because, you know, the next step is extinction. For this species, natural deaths are really rare. And, you know, at their peak, about 15 years ago, they were still nowhere near their one-time abundance. You know, 500 years ago, there were 10 times the peak that they'd reached then at 500. They're now at 384. And they continue to face a whole gamut of different threats.

And I talked to Susan Parks and ecologist at Syracuse University about that. I don't know any North Atlantic right well that doesn't have a tragic life. story if they're, you know, made it to adulthood. Getting people to care and have hope, if you just see a whale on the beach, you don't know anything about it, like it's upsetting. But if you know that that was a 15-year-old animal that just had her first baby and had like suffered all these horrific injuries for, you know, like it makes it a lot viscerally more upsetting. Right whales are sometimes called the urban whale because they are swimming relatively close to shore. And because of that, they face great risks, you know, particularly

from entanglements in fishing gear and then also marine vessel strikes. The other factor is climate change and that has shifted the right whale's preferred food where there are an abundance of food there also has happened to be an abundance of these threats.

2017 was a really important year for the whales and also for policymakers and it's because that's the year that they had 17 whales die in Canadian and and U.S. waters from fishing gear entanglements and ship strikes, vessel strikes. That's when the National Oceanic and Atmospheric Administration, NOAA, from the U.S. government,

would declare an unusual mortality event. And it was a significant death for a species that was already in trouble, because since 2010, it was already facing a decline. It had peaked at about 500 individuals in the population at that time. and then for a decade after that was just in decline. And in 2017, that was probably the first time I had ever heard of what a North Atlantic right well was. And I would say that's probably true of any Canadians. I come from Newfoundland Labrador.

If you go out on a whale watching boat, you're very likely going out to see the charismatic humpbacks, right? I mean, this is not a particular species that I would have seen close to shore growing up in western Newfoundland. And when I think that news headlines struck, it was alarming because all of a sudden this whale I'd never heard of was being caught in fishing gear and struck by vessels. And you could see this real conundrum. I mean, I grew up in fishing communities and, you know, you talk to people on the wharf. Nobody wants to hurt a whale. And yet here was examples again and again and again on both sides of the border where that was happening. Fast forward to now, and as if the fishing gear entanglements, the vessel strikes, and the added problem of climate change weren't enough, now researchers are learning about a new and rising but lesser known threat, ocean noise pollution.

When it comes to North Atlantic right-will language, researchers are really now just learning more about how sophisticated their repertoire is. In fact, they still don't know very much, and I talk to Mark Baumgartner about that. They're kind of like humans. They, like, you don't talk all day long. There are long stretches of the day where you don't talk for a variety of reasons. Right whales are a little like that. They'll talk for a few minutes, a few tens of minutes, and then they'll shut up. And they might shut up for hours.

We actually don't know a lot about that. But for those of us who have sort of been around Wrightwells and recorded their sounds, we have a sense that that's kind of what they're doing. And a lot of time, they're just quiet. When North Atlantic Wright Wells do communicate, it's complex. They can groan, moan, and call. One call we do know quite a lot about is the up call, and I think that has to do with the frequency with which it's used. It's a social call. It's a contact call. And not only do researchers now believe that it's hello, it's actually self-identifying.

So it's hello, I'm Jen. And it's a particularly important call for identifying one whale to another, and so generating a lot of social activity. For right whales, we get them all. Like males will make the up call, females will make the up call, females will make the up call. That's Mark Baumgartner again. It's a really simple call. It goes and it's it's really easy to recognize in the pitch tracks. It's really easy to recognize by here. An up call is a call that you know as the word implies starts low and ends on a higher pitch. Another way that Mark talked about how North Atlantic right wells you sound is to communicate about food. One strategy is for every, every whale for himself.

You just go out, and if you find food, great, if you don't, tough luck. Right whales probably couldn't exist if they did that. Probably when one animal finds food, he kind of blabs about it and brings in maybe other animals. And then they start blabbing, and like, when we find right whales, we don't tend to find one or two right whales. We find these, like, 10 or 20 right whales. times a hundred right whales. Well, did they all just find this one place by accident? No,

they've used sound to communicate to one another to sort of cast a bigger net to bring other animals in. What Mark is talking here about whales congregating to find food is not unusual. And a great example of this is the aggregation that was seen off of New York and New Jersey last year. Researchers had never seen that before. And there was a high percentage of the whales that congregated on Hudson Canyon. So you had a case where a few wills found a great feeding ground and communicated that very likely to others and formed an aggregation.

In addition to the upcall, scientists now have identified another vocalization called gunshotting. And I spoke to Hanson Johnson, a research scientist at the Anderson Cabot Center for Ocean Life at the New England Aquarium. And he told me about lacrosse. We recognized him as an older male, and he was engaged in this really interesting surface behavior called head pushing, where they sort of lift their heads and then bring them down with some force and create a little bit of a wave in front of them. And he was just doing this repeatedly, repeatedly, repeatedly, and then he would do a shallow dive for a short period and then come back up and continue head pushing, head pushing.

pushing, head pushing. And you could see this really distinct pattern in the gunshots, very regular gunshotting. And then when he would go down and dive, the gunshotting was replaced with this really complex and intricate series of moans. And it just really was eye-opening the level of complexity. And then he came back up to the surface and started gunshotting again. and did this for hours, and it's sort of this coordinated dance all by himself. While North Atlantic right wells make loud sounds, you know, they're calling out hay to one another through the upcalls, they're gunshotting as we're hearing, they're moaning and groaning. The other discovery that researchers have made is that when it comes to mothers and calves, they have

quite delicate vocalizations, and they liken it to whispering. We were actually trying to get more information on mother-calfeer acoustic behavior, because that I felt was really a gap. That's Susan Parks again. Pregnant females are numerically the most frequent animal that's migrating down the coast, close to shore, and we really didn't know if their acoustic behavior was the same as other animals that we've studied in their habitats, and so we didn't know if they were going to be detectable with passive acoustics.

monitoring. Maybe when they were pregnant, but when they had a young calf, you know, I was very curious whether they would be as chatty or whether they'd sort of be quieter to sort of avoid detection from other whales or potential predators for the calf. I spoke to Susan because she had an opportunity to listen in on the same whale, Harmonia, at multiple ages when she was one, nine, when she was pregnant and had her second calf, and again at 15 years old. And so Harmonia was a really interesting part of that study in that she was tagged on the calving grounds when she was pregnant and so we have a really nice recording of her and she was making lots of sort of louder contact calls so the up call she was producing those yeah a few weeks later we tagged her again

but this time she had a young calf with her and so she had given birth in the intro and just the sound production from her with the young calf was just totally different switched to these really sort of almost like quiet grunt sounds instead of these upcalls. That finding that mothers and calves whispered to one another or acoustically hiding became a really important finding because if noise is disruptive to adults, imagine how disruptive it is to a mother-calf pair who are quietly communicating.

And for a species that is really dependent on that reproducing mother to add calves to a population that is dying from unnatural causes already, it means that, well, they could become separated and in that case, the calf could die. Right, well, scientists have to know where they are. And to do that, they depend on surveys from sea-going vessels, airplanes. And in this case, acoustic feeds from hydrophone mounted buoys or autonomous gliders. Hanson Johnson at the New England Aquarium explained to me what passive acoustic monitoring is. Passive acoustic monitoring is this idea of eavesdropping on whale communication, listening for them to basically figure out. where they are at the ocean. There's many ways to listen in to the whales. And when we went out on a research vessel with Mark Baumgartner, we had an opportunity to see, I think it was the Cadillac version, really, of what you would call this.

Passive acoustic monitoring, in this case, it's relying on these gliders. So they're moving through the ocean independently, but Mark is able to continue to track them on his computer while also listening for whale calls with hydrophones, which is essentially an underwater microphone. The glider has wings on it, and so as the glider is going down, it doesn't just go straight down. It goes down on an angle. It glides, just like an airplane glider. You tow an airplane glider up to altitude. You let it go. It's dropping, but because it has these long wings, it drops forward, and so it can fly forward. Same thing for the glider. It dives forward, and then when it gets close to the bottom, it changes its buoyancy and starts to rise.

Doesn't rise straight up, it rises up. So the glider's always sort of moving in this V-shaped pattern. The gliders are about the length of an average dinner table, and they look like bright yellow torpedoes, almost like mini-submarines. So the glider we're about to pick up has been in the Gulf of Maine all over the past three and a half months. So remember, every two hours, the glider comes to the surface. Not only is it sending home information about, like, this is where I am and this is what I've been doing, it also sends home all that science information, including the whale detections. So they're autonomous in that researchers like Merck can, you know, send GPS coordinates and signal for the glider to go in a particular direction.

And the glider can continue to do that while sending data and sound and information. back to Merck and other researchers so that that information can be used to cue attention to where right whales are located. So gliders are able to be in 24-7 operation. They're weatherproof. They're able to, you know, hear for whales round the clock, meaning that people don't have to do that. I mean, you can imagine that comes with a decent price tag.

There are other methods to detect and record North Atlantic right whales. It requires researchers to deploy hydrophones from a vessel, but it's a much simpler way of being able to do that. Hanson Johnson told me about one of the ways that he's doing that. Well, it's basically just a battery, a small acoustic recorder inside a waterproof box strapped on top of a repurposed lobster buoy that can then just bob around. And the hydrophone is suspended underneath it. So that's an underwater microphone that's suspended underneath it. And so it's a little self-contained, but very inexpensive, sort of low-budget style system for collecting these recordings.

Very different and much less sophisticated than like an ocean glider or, you know, oceanographic mooring or any of these other autonomous systems. Another approach is what Susan Parks use, these D-Tags or devices that are actually attached directly to the index. individual whale. And so very different from gliders or stationary buoys or just dropping a microphone in the water, these are recording devices that temporarily stick to individual whales, kind of like a suction cup, and they capture sounds from the whale's perspective, both, you know, what the whale is saying and also what it's hearing, and then it detaches and floats up for recovery. So the D-Tags were particularly helpful for a whale like harmonia because you can learn about a specific whale's experience. You know, gliders and buoys, they monitor the whole population, but you don't

necessarily know who you're listening to. In this case, you know exactly that you're listening to a tagged whale. Think about this as the difference between wearing a body camera on one person versus setting up a security camera in a room or an area. You get really different information, and in the case of a tag, you're hearing these delicate sounds that you otherwise wouldn't be able to pick up on the security camera. In addition to listening for the whales, what researchers are picking up is that no matter where the whales are along their migratory path, they're facing man-made noise. For whales to have an increase in man-made noise, at best, it's an annoyance, and at worse, it's a threat to their survival. It inhibits every action that they're trying to make in the ocean.

When I talked to Mark, he talked about what it's like from a cocktail party perspective. It's a noisy ocean. It's a noisy ocean just with the biological sounds. But we, of course, as humans, put extra noise in. Like this boat is noisy. And if we get closer up to the shipping lanes where you see these big, big ships, it's astounding how much noise they put into the ocean. And we worry about that, not so much for a ship like this, but the big ships and the volume of traffic puts out so much noise.

It's like being in a cocktail party all the time. Like you just, you have to be close to someone to talk to them. The whales are dealing with that all the time. Another way to think about this, as Susan put it, is it's like being in a constant soupy fog. That like, you know, on a clear day you might be able to see pretty far. but if, you know, you increase the sort of fog in the area, it could get to the point that you just can't see anything like in front of your face or you could still see a kilometer or whatever.

I mean, there can be natural fog. There can be storms and things that are noisy. The whales are not going to be hearing each other during a big storm because the waves crashing and everything are really loud. But I think we're introducing more fog more often acoustically. The sort of the maximum range that they can hear each other is definitely probably shrunk in some of the deeper habitats? Shipping, energy development,

marine construction, sonar. It's noise because it falls in the same frequency that the whales are using for communication. So this could be smaller large boats, wind platform development, seismic activity from oil and gas. It's happening at a low frequency, and it's right in that right-well calling range and hearing range. Susan Parks tells me about this one time when she's listening to what's called a surface active group.

So that's when you've got a group of whales that are engaging in this energetic social behavior. They're making a lot of vocalizations. Often it's the females that are making a lot of those vocalizations. But then a tanker comes along. I mean, you essentially just see this like wall of sound encompassing the entire sound spectrum. and like the boat just kept getting louder and louder. And I really wanted to hear the whale, so I just kept listening. And I think I had a headache for like two days because it just got louder and louder and louder.

And the whales just kept going. But like the surrounding whales that could hear them, that space just kept getting smaller and smaller as the boat got closer. One of the things you frequently hear about, particularly in New England where there's been offshore wind development, is that that's to blame for a lot of the ocean noise pollution and affecting the whale. And I mean, researchers are studying that now, but one thing that I talked to Mark Baumgartner about is that researchers do know that although offshore wind development ramped up during a period when whales were dying, the whales were already dying from known causes. We know the causes of those deaths. We know that it's fishing gear entangments and ship strikes. Along comes offshore wind, we don't see this suddenly, there's a whole new category. of mortality. We don't see mortality that are attributable to offshore wind in any way. So the evidence just isn't there. However, scientists like Mark are working to ensure that wind development is done safely with proper monitoring, including assessing noise levels.

One thing that researchers know, is that ocean noise is having physiological effects on whales. Researchers know that loud or persistent noise triggers stress responses, and I talk to Hanson Johnson about a study of whales and their stress response after 9-11. Researchers were out in collecting fecal samples from right whales before and after September 11th. And the events of September 11th and the subsequent cutting down

of ship traffic and air traffic, created a little bit of a natural experiment where for a brief period of time, right whales were subject to much less noise than they were typically. And that was reflected by a significant decrease in the stress levels of these whales. In addition to stress, there's also physical damage, extremely loud sounds can, cause temporary or permanent hearing damage, and in severe cases, internal injuries. Because of all of the threats on this species, researchers have seen their living shorter lifespans, they're growing shorter, they're taking longer to carry calves, all signs of a species under constant stress.

The issue of man-made noise is so pervasive for Wright- Wells because they can't escape it. In the entirety of the migratory range, they face ocean noise. pollution and yet they depend on sound for every aspect of their existence to navigate to find food to communicate and to bomb with one another for a species that's completely dependent on sound as their primary sense it means that ocean noise is drowning out their very existence when it comes to ways to reduce ocean noise pollution for North Atlantic right whales and other species researchers know of several effective ways of doing that. So not surprisingly, one of those is to remove the threat

entirely. So when you think about shipping or fishing, that means things like rerouting vessels, not all the time, but seasonally or dynamically when whales are present, and in the same way issuing fishing area closures. So the same approaches that can actually reduce other threats, you know, you can reduce ship strikes, for example, you can reduce fishing gear entanglements, will also be effective for reducing ocean noise. I think but the real nut to crack is how do you balance human development with the conservation needs of North Atlantic right wells and researchers talk about, and policymakers too, coexistence.

How do you solve multiple problems at once? Keep noisy activities away from whales in space or time is one of the ways of doing that. I mean, remove the threat entirely. use technology to dynamically manage where the whales are present or where they're known to be. So that's where things like detection systems of the buoys and the gliders in U.S. and Canadian waters can be this constant reminder. Hey, there's right wells out here. Let's slow down and subsequently also reduce our ocean noise from shipping.

But the real burden of proof for reducing ocean noise is not on conservationists. It's certainly on industry, but it really comes down. to government to set policy. When it comes to Canada, Canada released a federal ocean noise strategy back in 2023, 2024. It was due to release a federal action plan and final ocean noise strategy. We couldn't clarify when when we asked Fisheries and Oceans, Canada, that question. I have heard it criticized as a plan for a plan, right?

Because what it attempts to do, and I heard this from fisheries and oceans, Canada themselves, that it attempts to take an approach to coordinate around this issue with the ultimate goal of reducing ocean noise and its impacts. But what that lacks is an understanding of targets, exact measures, regulatory steps that require industry to abide by certain noise levels, for example. So I think until that federal action plan is released and we see those specifications, it's hard to know, you know, is this a plan for a plan or are these actually regulations that we can test and measure progress against. When I started this series, I have to say, I worried that we would be simply documenting

the decline of a critically endangered species. They have a lot of cards stacked against them. But the whales are showing signs of growth. And it's slow growth, right? Over the last four years, the population has been moving in the right direction. After a decade of decline, and also a lot of learning on the part of researchers and policymakers to protect them. And now we see, in these last four years, the whales are doing their part. And I think what I hear from researchers is that it's up to us to do ours. When I spoke to Hanson Johnson, he said that this is again why it's so critically important to listen to the whales, that we have an opportunity to know them and empathize with this situation.

with right whales i mean there's always this direct link back to how do we keep this species from going extinct but i think there's tremendous value too and just like that sense of discovery and sort of developing this empathy to these these animals but there's i think a really strong motivation to understand these behaviors better because the conservation implications are are really big. When it comes to empathy, I think that's why the story of these individual whales are also so important. And lacrosse, harmonia, Nasset, all the whales that we spoke about are still alive. And part of the estimated population.

Despite all of the things that they've had to encounter throughout their existence, they will continue to teach researchers about this and other threats. and most importantly, how to beat the odds. That was environmental journalist Jen Thornhill Verma, who produced this piece as part of the Globe and Mail's Entangled series, in partnership with the Pulitzer Center's Ocean Reporting Network. That's it for today. I'm Cheryl Sutherland.

Madeline White and David Crosby produced this episode. Our producers are Madeline White, Michal Stein, and Ali Graham. David Crosby edits the show. Adrian Chung is our senior producer, and Angela Pichenza is our executive editor. Thank you for listening.