A Cook Inlet beluga whale calf and its mother are shown breaching the water in the Big Susitna River in Alaska in this photo taken in May 2023. A new study shows that commercial shipping activity is impacting the vocalizations of these critically endangered whales.
Courtesy Arial Brewer
From humpbacks to orcas, whales and dolphins are renowned for their underwater vocalizations, whether it’s to impress a mate, find prey or strengthen social bonds. But beluga whales are especially vocal, with a complex language of whistles, chirps and rhythmic calls that have led to them being called the “canaries of the sea.”
For the first time, a team of scientists has documented the unique vocalizations of Cook Inlet belugas, a critically endangered population native to Alaska. The roughly 300 of them remaining live year-round in the cold, cloudy waters surrounding both a military base and the port of Anchorage, the busiest shipping port in the state. The scientists found that the low, rumbling noise of commercial ships either partially or completely masked the seven most common calls the whales made when passing through their habitat multiple times a week. Arial Brewer is a Ph.D. student at the School of Aquatic and Fishery Sciences at the University of Washington and the lead author of the recently published study. She joins us to share the findings and how noise from human activity is threatening the survival of Cook Inlet belugas.
The following transcript was created by a computer and edited by a volunteer:
Dave Miller: From the Gert Boyle Studio at OPB, this is Think Out Loud. I’m Dave Miller. From humpbacks to orcas, whales and dolphins are renowned for their underwater vocalizations, whether it’s to impress a mate, to find prey or to strengthen social bonds. Beluga whales are especially vocal. Their complex language of whistles, chirps and rhythmic calls have led them to be called the “canaries of the sea.” For the first time, a team of scientists has documented the unique vocalizations of Cook Inlet belugas, a critically endangered population in Alaska. And the scientists have learned more about just how disruptive human sounds, especially those from commercial shipping can be. Arial Brewer is a Ph.D student in the School of Aquatic and Fishery Sciences at the University of Washington. She is the lead author of the new study and she joins us now. Welcome to the show.
Arial Brewer: Thank you. Thanks so much for having me.
Miller: Thanks for joining us. How did you become interested in belugas in particular?
Brewer: That’s a great question. I’ve always been really interested in marine mammals from a young age, and particularly, I guess their communication and kind of their societies. I’ve worked on a wide range of marine mammals and started working on belugas in 2017 at a position with NOAA, the National Oceanic and Atmospheric Administration, here in Seattle. And I never thought I’d get to work on belugas, but kind of got to dive in. And it’s just been fascinating ever since starting with them.
Miller: How much was known about their vocalizations compared to other marine mammals?
Brewer: So, I think when you hear about belugas, a lot of people have heard of them, like you said, [as] the “canaries of the sea”, and when you listen to them, you’ll know why. They’re very kind of bird-like sounding. A lot of people are familiar with humpback song or maybe with killer whale calls or kind of the high-pitched whistles and buzzes of dolphins. Belugas sound very different. I always like to tell people they sound kind of [like] a mix between aliens and birds. Hundreds of years ago, mariners would hear them through the hull of their boat. And that’s kind of what gave them the name “canaries of the sea” because they kind of sounded like birds singing below the surface of the water.
They’re really interesting because they produce a really, really complex wide range of calls, and they do a really interesting thing called gradation, where they can kind of turn certain calls into other ones along a continuum without a break. I kind of like to describe this as, if I were able to whistle, then say my name, then laugh, then whistle again, all without taking a breath. And there’s some other marine mammals that can do that, but not a ton. And so it’s that kind of gradation ability [that] allows them to produce a really wide range of calls.
Miller: Let’s have a listen to one of the recordings you made and then you can tell us about what it is we’ve just heard. Let’s have a listen.
Brewer: Sure.
[Beluga whale sounds]
Miller: So there’s a lot of sounds all at once there.
Brewer: Yeah, there’s a lot going on there.
Miller: What is going on?
Brewer: So that is multiple whales calling together. We don’t, unfortunately, have the number because we were passively listening with an acoustic recorder. But I like that clip because it shows kind of the range. And also they make three broad categories of calls: whistles, pulse calls, and combined calls, and combined calls are a combination of whistle and pulse calls together, simultaneously. And I like that clip because there’s all three of those categories in there. There’s a lot of different call types within those categories happening, but you can hear the range of calls they can make.
Miller: Your study, as I noted briefly in my intro, was the first one to document the unique vocalizations of one very specific population of belugas: Cook Inlet beluga whales. What are the challenges of studying this population?
Brewer: This population is tricky. Like all kinds of Arctic and sub-Arctic marine mammals, it’s remote, it’s really hard to access throughout most of the year other than summer. Cook Inlet, in particular, is very turbid. There’s a lot of glacial runoff and so the water is very murky. So it’s hard to kind of see these whales and you can’t see them underwater. And also these whales were hunted by Native communities for subsistence purposes until the late 1990s. So these whales are very skittish of boats, they’re very skittish of people. It’s really hard to get close to them. And there’s only about 300 left. So it can be quite hard to find these whales sometimes.
I think that all of those factors combined with kind of a harsh environment makes them pretty difficult to study. So that’s kind of why we’ve implemented passive acoustic monitoring, because we can place acoustic recorders all over the inlet and kind of eavesdrop on their world without actually having to physically be there year-round.
Miller: Oh, and without having to, say, strap a microphone on them the way scientists have been able to do, I think, for orcas, right?
Brewer: Correct. Passive acoustic monitoring is nice because it doesn’t interfere with their behavior. But it is also limiting because when we can tag the whales, like you mentioned with killer whales, we get a really good sense of what’s happening at that whale and how many whales are around. With passive acoustic monitoring, I kind of like to think of it as like our eyes are closed, but our ears are open. So we don’t know exactly how many animals are around. We don’t know the age classes of animals that are around, but we get a sense of their acoustic environment. So what they’re hearing as far as humans-caused noise, ice, seals in the area. We get an acoustic picture of what they’re hearing.
Miller: What were the biggest findings in your mind from your multi-year study, listening to the sounds they were making and the sounds they were being exposed to?
Brewer: Let’s see… in terms of their calls, we found a really rich, unique and wide range of repertoire, which was really exciting. We found differences. I sampled two locations: Susitna River kind of at the northern end of Cook Inlet, which is their prime summer habitat for feeding on salmon. And then in the winter, they kind of get pushed down by sea ice. And we sampled Trading Bay. I found that those two locations have significantly different call use patterns. They’re using different call types in those areas, so that was really interesting.
Then as far as the noise, we knew that human-caused noise, or anthropogenic noise, is a problem in this area, but we’ve never been able to kind of quantify how big of a problem it is to them. And so we took the most commonly used calls that they emit and we ran an analysis compared to ship noise. And we found that all seven of the calls we used were completely masked when ship noise is close or loud. So that was a really kind of compelling result. It was really, really interesting to see. Obviously, that’s not a good result for the whales. Ideally, their calls would not be masked by the noise, but being able to find that they were completely masked by the noise can help us kind of try to further understand this and try to mitigate some of those actions down the road.
Miller: So their calls could be completely masked by a ship that was close. How often does that happen? I mean, can you give us a sense for the habitat of these whales and how frequent commercial ships are, and even the other human-caused things that are making noise exactly where these whales live?
Brewer: Sure. The area we did this was kind of that main critical habitat for them. If anyone happens to look on a map, it’s called Big Susitna River. And that is the kind of right in the center of their critical habitat. And it’s also about two kilometers away from the commercial shipping lane and it’s really close to oil and gas rigs, which make noise. It’s close to the international airport, and it’s close to a large military base. And so there’s a lot of noise in this area. Those are kind of the big things.
There’s not a commercial whale watch industry up there, but there’s a lot of private and commercial fishing boats that kind of zip around. The Port of Alaska is constantly kind of trying to enhance their infrastructure. So there’s a lot of pile driving that makes a lot of noise. So, unfortunately, kind of the main area where they live is really, really loud and these whales are exposed to it year-round. And so just kind of getting a better sense of that and how we can kind of try to mitigate that a bit is kind of our goal. But yeah, unfortunately, these whales don’t really get a break in the noise, unfortunately. And they don’t migrate out of Cook Inlet, so they’re kind of exposed to it year-round.
Miller: But you found that even if a ship is 10 miles away from a whale, if not completely mask, it could still disrupt communication. I mean, the sense I got is that these whales are always, at least, being disturbed by human noises and sometimes being truly in a kind of communications blackout, auditorily. I mean, is that a fair way to put it, that they can never escape human noise?
Brewer: Yeah. So in the kind of winter, early spring, sea ice kind of pushes them down into the mid and lower inlet. There’s definitely anthropogenic noise there, but not as much. So they can kind of go down into the lower inlet. But also, there’s killer whales down there. Killer whales will predate on belugas and there’s also not as much, it’s not where their main feeding rivers are. So, it’s kind of this balance of they need to be in the areas where they’re able to feed and breed and calf, and also protect themselves from killer whales. But also, those are the areas that are the noisiest. So, yeah, it’s a really complex problem because Anchorage is a really important hub for the entire state. That’s where the entire state gets its goods, and the military base there, it’s important, and so it’s a really complex problem. And as a scientist, I’m not sure which way the managers and the decision makers will go. But this is kind of an ongoing problem for these animals.
And yeah, communication blackout is, I think, a good way to put it. I kind of like to equate it to a really loud rock concert. So it’s like these whales are kind of at an extremely loud rock concert all the time and they’re not able to communicate fully, like if me and you were talking, you’d be able to tell I was talking to you, but you probably wouldn’t be able to hear what I was saying. And so that’s kind of the same, especially with mothers and calves that are trying to communicate and stay close to each other, that disruption of communication and contact can be really problematic for these whales.
Miller: I mean, if we’re going to stick with that metaphor, being at a rock concert, not being able to communicate using sound…And isn’t it the case [that] the other important point here is that sound is the main way they communicate? So it’s almost like humans who are sighted, being at a rock concert where they can’t hear each other, but they also can’t see each other.
Brewer: Yeah, that’s a great point. These animals can see, but like I mentioned, the water is really turbid, so vision is kind of useless. And so yeah, this population and other beluga populations really rely on sound. That’s kind of their primary modality for not only keeping in touch with each other but also being able to find prey. And so that disruption can cause a lot of different effects across social cohesion and feeding and being able to detect predators. So, yeah, that’s a good way to put it. It’s kind of like we’re blind.
Miller: Let’s have a listen to another of the recordings you made. This is not a whale. This is the sound that’s disrupting that. This is a commercial ship from an underwater microphone.
[Loud rumbling sounds]
Brewer: Yeah. Not a fun sound to hear all the time.
Miller: You’ve listened to thousands of hours of recordings of the sounds that these beluga whales make. What has that been like, just sitting there with headphones on or speakers listening to these mammals, these animals that are so much like us evolutionarily, that are also huge and live in cold waters?
Brewer: It’s just really interesting. I’ve always been really fascinated with the soundscape of the ocean and because marine mammals, all marine mammals, even seals and sea lions, are vocal, it’s kind of a way to eavesdrop into their world without affecting their behavior or disturbing them. So this repertoire project was really interesting. It is, like you said, very tedious work. But every time I would find a new call type. It was just fascinating because we don’t know the context of their call types. And so every time I would find one, it was just interesting to think about which whale is making this call and what’s the context in which they’re doing it? Is that a calf making that call? So it was just, I don’t know, kind of kind of like a little treasure hunt. Every time you find a new call, it’s kind of a cool little piece of treasure that we get to add to our little piece of knowledge and down the road, maybe figure out what these calls mean.
Miller: Let’s have a listen to one more call. This is a short call that we’ve looped so people can hear a couple examples of it in a few seconds.
[Beluga whale sounds]
Miller: So if you’re lacking so much information about what’s happening in an individual whale’s life when they’re making a call, are you ever able to say, this sound means this thing?
Brewer: So that’s what I’m actually working on right now, on a project I’m really excited about. I’ve been collaborating with a really wonderful team of conservation biologists that actually work on the military base. They do behavioral observations of the whales when they’re in this area and they get really fine-scale details. They get the number of whales, they get how many calves, juveniles, adults, the behavior, what the tide is doing. They’ve been wonderful and have allowed me to put acoustic recorders where they’re observing. And so for the first time for this population, we kind of have a paired behavioral and acoustic data set. And that’s kind of what I’m trying to figure out is when are they making these types of calls? What’s the context? And I have some pretty interesting preliminary results I can share.
One thing that I found that was really fascinating was the combined calls that I mentioned earlier. So it’s basically when they make a whistle, like you guys just heard, and a pulse call, together. And to kind of give an idea of what that would be like, that would be like if I could say my name and whistle at the exact same time, which I definitely cannot do. These combined calls were the rarest of the repertoire. They only made up about 1% of the repertoire. But in other studies in other populations, scientists have hypothesized that these may be contact calls. So we’re not sure if it’s at the level of the individual or a group, but kind of a contact cohesion call to keep animals together and to maybe show identity. So finding these calls in particular was really fascinating because they’re rare.
I found about 20 different unique contact calls, or combined calls at this point. And so what I found in this new research that I’m working on right now is that they only make these combined calls when calves are present. And so that’s really interesting and kind of supports the idea that these might be kind of mother-calf contact calls. So, yeah, stay tuned. We’re hoping to get this work published later this year. But I thought that was a really interesting result.
Miller: And just before we go, what do you hope policymakers will do with your research?
Brewer: I really hope that… I don’t know if mitigation or change will happen because of our study, usually several studies are needed. But I live in Seattle. One thing the Port of Seattle and the Port of Vancouver are currently doing for the southern resident killer whales here [is] a voluntary slowdown program where they decrease the speed of the commercial vessels, which decreases the amplitude of the noise. So that could be something that the Port of Anchorage might be willing to do, is just slow down the vessels when they’re coming in and out to decrease the noise. I’m hoping that at least the study will lead to conversations about how we can try to mitigate this impact. Yeah, I mean, that’s kind of up to the managers and the stakeholders, but I’m hoping it at least leads to conversations in the right direction.
Miller: Arial Brewer, thanks very much.
Brewer: Thank you guys so much.
Miller: Arial Brewer is a Ph.D student in the School of Aquatic and Fishery Sciences at the University of Washington, the lead author of a new study looking at the vocalizations of the Cook Inlet beluga whales, as well as the shipping noise that they are being impacted by.
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