By Walt Hickey
Welcome to the Numlock Sunday edition.
This week, I spoke to Amorina Kingdon, writer for Hakai Magazine and author of the new book Sing Like Fish: How Sound Rules Life Under Water. Here's what I wrote about her article, “Quieting the Global Growl”:
The vocalizations made by baby beluga whales come in at 120 decibels, 22 decibels below the calls of older belugas. That difference has a significant impact on how those newborns can be heard, with newborn calls reaching only 350 meters away, compared to the 6.5-kilometer range for adult belugas. That’s a problem given how loud the oceans are getting thanks to human activity: In 1980, the merchant shipping fleet was 700,000 ships, which today stands at 2 million.
We spoke about how sound works underwater, how it affects and is used by aquatic life, and where we stand on regulating underwater noise pollution.
Kingdon can be found at her website or on Twitter.
This interview has been condensed and edited.
Amorina, thank you so much for coming on.
Thank you so much.
You are the author of a brand-new book called Sing Like Fish: How Sound Rules Life Under Water. You have been a fixture at Hakai Magazine, which is a personal favorite of mine. This is such a fascinating topic, I'll just throw it to you: What made you want to write a book about how sound works under the water?
I love the word fixture. Thank you so much for that.
Hakai covers coastal science and coastal society, and I was starting to see stories coming across my desk that were to do with how sound pollution or how human-made sound, anthropogenic sound, is impacting life. I saw a couple of really interesting studies. You hear about things like, oh, this sounds really loud and it injured an animal, or something like that.
But then I saw this one study that was about cleaner wrasse on a coral reef. Those are little symbiotic fish who set up a station on a reef and then bigger fish come by to get clean. The wrasse eat the parasites off them, they get a meal, they don't get eaten, etc. When there was motorboat noise around the reef, the cleaner wrasse tried to cheat more often. It seemed almost like they got distracted or anxious or something, though that is definitely anthropomorphizing. They just seemed to be taking bigger bites, or would sneak scales off the bigger fish, and then the frequency with which the bigger fish would chase them in retribution also changed.
I had this realization in my head that impact on animals is not always as obvious as injury or death. Sometimes it's just their interactions. Even with wrasse, it's between species, not just between two fish of the same species. So I started to keep an eye out for stories about all these ways that sound could affect animals underwater.
At the same time, I was starting to see more and more stories about this but there was always this gap in my head, like a cognitive dissonance when I tried to actually picture it. What I mean by that is, if you think of an oil spill or climate change, warming water, or you think of blunt force trauma, like a ship striking a whale, it's really easy for a human to picture that. You think of a bird that got oil on its feathers and it's like, yeah, I can see that. That's obvious.
But whenever I hear about ship noise hurting animals, there was this little gap in my understanding. I just couldn't picture how sound might really hurt an animal. I think that's because people, when we put our heads underwater, we don't hear very well. Our ears are not evolved to work underwater. You just think, well, if there's no sound, how can it really be a problem?
The more I looked into it and started covering these stories, the more I started to realize that just because we don't hear sound underwater, that actually doesn't mean there's no sound there to hear. Sound is really, really prevalent underwater and a lot of animals tap into it. The reason why I got interested in the topic was because I was reading studies like the wrasse, but the reason why I wanted to write a book about the topic was because I wanted to tell people and create an explanation that would fill that cognitive gap of why sound can have an impact in the first place. How can it be so important?
That’s a little bit too complex to explain in a short news story, but I thought if I wrote a book about this, then everybody who reads the book will have that understanding and maybe we'll close that gap a little bit. Then the next time you read a story about the impact of seismic air guns or shipping noises or pile drivers, you’ll have an understanding of exactly how it is that that can actually have an impact.
I love stories about ecology in general, and I think one of the hardest things about it is that as you get further and further away from the human experience, it can be hard to empathize, and when we do empathize, sometimes we have to use a crutch like anthropomorphizing things.
I really enjoyed the book because it really drives home what sound is to a fish and how it's different than what sound is to us. I kept on coming back to the idea that sometimes sound is like heat, like on a hot day in New York, people are a little bit rowdier than they otherwise would be, right? The book really gets to the idea that sound is different things for different organisms. I was wondering if you'd be interested in speaking to some of that.
Basically, we have this idea that the only way to hear a sound is with an ear, right? That's what it does. That's what an ear is.
But first of all, ears evolved in the water. Ears evolved in the ancestors of fishes hundreds of millions of years ago, before animals ever went onto land. Interestingly enough, our ear, with all of its massive mechanisms inside, is an evolution that happened to help sound get from a mechanical wave, because sound is a mechanical pressure wave, to the point where it could be transduced into an electrical signal in a neuron. All of this stuff in our ear is an evolution for where we are now, which is mammals on land. But our idea of an ear is actually a really, really small subsection of what ears are, or what they can be, because an ear really is just any organ dedicated to hearing.
On top of that, partly because sound works differently underwater and partly because of how important it is, even before a purpose-built ear evolved, animals still had organs like lateral lines, or hair cells, or other structures that had other abilities but could still detect sound regardless. The ancestors of today's corals and crustaceans, all those animals, they also have structures that can detect sound, even though they're not ears, because they're not only for hearing.
Once you start looking at all of this stuff — and I'm sure I did an absolutely terrible job just now trying to explain a couple hundred million years of evolutionary history — one of the really mind-blowing things that I learned, the more I was looking at this, was that ears are not the only way to hear, and detecting the pressure difference of a sound wave is not the only way to even tap into sound. Our eardrum uses a pressure wave to respond to that mechanical pressure wave and then move on through the ear. For an animal that's using an otolith over a bed of hair cells, or using a statocyst with an inert mass, that's using the particle motion of the water that's causing the pressure change.
Without getting too much into the weeds, the more you start looking at the actual mechanisms of this, the more you realize that at the end of the day, detecting a sound really just involves moving a hair cell so that it fires a neuron that says to the brain — or whatever nervous system it has — that it's detected the sound. An ear, let alone a human ear, is such a tiny portion of that.
And then considering the fact that life and ears themselves evolved in the ocean, it actually makes a lot of sense that there are not only more ways of detecting sound in the ocean than we can ever dream, but actually marine life is really, really good at it. Around 90 percent of the species in the ocean are invertebrates. They don't even have a backbone, yet most of them probably have ways of detecting sound.
You have chapter about communicating among fish, and then you have a chapter about echolocation. I'm also interested in some of these other talents animals can develop using the phenomenon of sound.
As humans, we use sound a lot for communication. Sound is the medium through which we have language and verbal communication, and there are reasons for that. I am not a sensory biologist, but one of the coolest things I came across was the idea that because sound is a wave, it travels over distance, it travels in the dark, it travels pretty far. It works around objects. I think it's the only distance sense humans have that actually can wake us up from sleep and has a true startle response.
For all those reasons, it's a really, really good sense for sending alarm calls, identity calls or signals across distances. It makes a huge amount of sense that sound is the sensory modality that we use for a huge part of our communication and specifically our language, which can get complicated. You can modulate language a lot. You can modulate sounds a lot, with frequency, amplitude, and so on. But when you look at animals, I think we have this bias that if they're making a sound or if they're detecting a sound, they're using it for communication.
What we have to learn is that communication is just one thing. If you're an animal in the water, even if you don't make sound, even if it's really good for you not to make a sound because you're a prey animal or something like that, it's still very, very advantageous for you to be able to detect sound just to figure out what's going on in the world around you. In the water, light is absorbed a lot quicker than it is in the air. Sight and light underwater are not particularly good distance sensors. If you're an animal in the water, sound works 4.5 times faster underwater than it does in air. It travels a lot further. It's absorbed less easily.
So, if you're underwater, it's really, really advantageous for you to listen to detect predators or detect prey. It’s just perception of the world around you, and that can lead to wayfinding. A lot of smaller animals will use sound to figure out where they're going. They'll move toward the sound or they'll move away from a particular type of sound. You see this with baby larval reef fish and corals: They'll move toward or sink down toward the sound of a healthy reef, even though they themselves don't make sounds at all and they don't use sound to communicate between each other.
So you have wayfinding, traveling. Then you have, of course, communication, which becomes more of a thing with larger animals, with mammals. You also have what's called auto-communication, which is echolocation.
This is what some whales and dolphins have been able to do, which is where they make a sound themselves and then they listen to the echoes, and they can read or detect shapes, echoes, prey, seafloors, or objects in the distance that you couldn't visually see. Because sound is different from light, it can actually penetrate through objects so they can get a sense of thickness or content. They can get a sense of all that stuff from echoes.
When you hear about sounds underwater, you immediately think, oh, the animal's quote-unquote talking, or they're communicating. But what we're seeing when we look at animals outside of the charismatic marine mammals is that they're using sound for echolocation. They're using sound for hunting. They're using sound for wayfinding, for finding prey, listening for predators, running from danger, running toward the home reef. It's used for everything.
It also seems like it's one of the most acute senses that many animals in the ocean have. Eyesight can be hit or miss depending on water quality and things like that, but it really seems like a lot of these animals are using sound as their primary way of just existing within their environment.
Some of them for sure. I think for many species, we honestly don't know because we just haven't even really started to look. But it makes a lot of sense that it's a very key sense.
Now, I didn't focus on the discussion of how sound compares to light underwater. There are studies on how quickly the water absorbs light and obviously the fact that in coastal waters it can get really murky and visibility is really bad. I think there's a lot to be looked at when it comes to chemicals in the water and the sense of scent underwater. Obviously, chemicals still disperse through the water; they spread it through currents and then they can travel over distances, too.
So it's not to say that sound is the only way that animals are perceiving things underwater. If you're an animal in any environment, you're going to really need to be able to also detect what chemicals, taste and scent are around you. But yeah, sound is really, really critical for many animals. It's a question of life and death for many of them.
It's a really great book. It's a great tour through a really pressing issue and a thing that I don't think a lot of folks think about. Again, a lot of what your book does highlight here is that humans are making a material impact on the subsea soundscape in ways obvious and otherwise.
I'd love to hear a little bit about your assessment of where things stand when it comes to how sound is regulated or lack thereof when it comes to global ecology and where we go from here.
Right now, with the exception of a couple of regulations in the EU, there aren't really any regulations on underwater sound anywhere in the world in terms of limiting the baseline amount of sound that can come out of vessels or air guns or things like that.
Part of that is because we're just realizing how important sound is underwater. We're just doing a lot of the studies and just discovering how a lot of the species are affected that aren't marine mammals, that aren't some of the fish that we studied in detail. So part of that is just that we haven't really started looking at the data until now, which is why it's so exciting that we are looking at the data and doing those studies now.
Part of it is also because underwater sound is actually really difficult to measure. I had a really interesting interview with someone who was describing to me how ships make noise and where the noise comes from: It mostly comes from its propeller from a process called cavitation. The bubbles form on the propeller and those bubbles pop, and they create this broadband noise that's really loud. But that noise can change depending on how deep in the water the propeller is, or how the wash along the hull is going. It spreads out. A container ship is a couple hundred meters long, so do you measure from the front, from the side, from the back? You'll get different measurements at all these points. Until very, very recently, there wasn't even any standard on how to measure sound underwater.
Also, a lot of the regulations right now about things like that are structured around the idea of a pollutant. An oil spill, or dumping something else that's toxic in the water. The noise would be considered a pollutant and would be classified as such, but noise isn't a particularly standard pollutant. It doesn't come mathematically. Two ships don't make double the noise of one ship. Sound interacts and it refracts and it bounces and it moves around. It's a really, really tricky thing to measure. And what's that saying, “what can be measured can be managed”? Well, until we know how to measure sound properly and really get a sense of exactly what we're talking about, it's really difficult to write a good regulation about what should actually be changed. That's one aspect of it.
Now, there are a lot of discussions that are coming up now. I know that the International Maritime Organization is discussing this among some states right now. There are also some efforts underway here in Canada, for example, to try to bring underwater noise into discussions of things like shipping lanes and regulations around marine protected areas. We’re starting to put it into the discussion, but we're still encountering that problem of general lack of data and general difficulty in measuring it. It's really important at this phase, I think, to do the studies and do the work on how different animals react to noise and what actually hurts them when it comes to sound underwater.
That work is being done, and that's good. But in order to make a good regulation, you want to make sure you're really discovering what is actually effective. And that's what we need right now, is to fill in the data gaps.
One last question on this point, actually, because this is a really interesting element that I think a lot of Numlock readers will like because of the data part. There's been comparatively a lot of study on charismatic ocean animals, the mammals that we all know and love. But you've alluded to this idea that it hasn't always been the case. Can you speak to whether or not we’re doing studies on uncharismatic aquatic life these days to figure out how sound affects them?
Yes, we are, actually. There are some studies that are going on. A lot of researchers are looking at a couple of different major groups of animals to see how they respond to different types of sound.
Some of the key groups underwater that need to be looked at are different classifications and different groups of fish, because different fish have different specifics in their ears. Some fish have very sensitive hearing; others don’t. Some fish are on the ground or the seabed and might also be affected by underwater vibrations in the seabed. There's a whole bunch of variety when it comes to fish.
Cephalopods are another big group. There are some studies going on right now with respect to squid, and I think we've found that when it comes to impulsive noises like pile driving or sharp, quick rise time noises, squids do detect them and they do react to them. The question now is, how intense do those sounds have to be before the squids are A) affected in their ability to go about their daily life, and B) potentially wounded or damaged by it? That covers a huge group of animals: cephalopods, squid, octopus, all that. But they definitely detect sounds.
There's also shellfish. Shellfish are really critical for a bunch of different reasons. One is that they're usually an important fishery species. We do know that shellfish can be affected by the sound of seismic air guns. There have been some studies in Australia that suggest that when scallops are exposed to the sound of air guns, they can develop changes in their fluid chemistry that suggest they're stressed. It's not something you'd notice if you were just looking at the animal quickly. Like, is this alive, is it dead? If it's alive, great. But it suggests that perhaps there's some ongoing stress that might happen.
The other thing to remember about a shellfish is that, unlike a whale or a fish or even a squid or an octopus, it can't really move away from a sound source.
Oh, interesting.
If you have animals that are right below a shipping lane or they're in the middle of an oil and gas field, they don't really have the option. Well, actually, they can move away, but usually not quite as efficiently as a whale or a dolphin. They can't just suddenly run away. They’re often a captive audience for noise and sound.
Other animals like crustaceans, crabs and lobsters absolutely detect sound as well, even though they also don't have what we would call an ear. They have hair cells in their antennae and they have structures in their joints that can pick up sound. There have also been studies finding that when they're exposed to chronic shipping lane noise and short, loud, impulsive sounds, those hair cell structures can be damaged — sometimes chronically, sometimes temporarily, sometimes permanently. That can also affect their balance.
Again, it's the kind of thing where you would look at it and go, oh, it's still alive, it's fine. But if you watch it for a while or you turn it upside down, it has trouble righting itself. So there are actually some subtle impacts that can have serious knock-on effects on these animals.
There are studies that are starting to look at those questions, and I'm really excited to see what they're coming up with over the next few years. A lot of that data has actually come out over the last few years, too, which I talk about in the book. And that's the kind of thing we need to know, right? Because that's going to help us make the right sorts of regulations.
That's great.
The final chapter in your book is basically from science to art, how to quiet an ocean. I don't imagine we have too many staff members of the International Maritime Organization listening, but what are some things that we should be thinking about when it comes to how to mitigate our potential sonic impact on marine life?
I think there are a couple of different ways to go about it, and a couple of different angles that would be useful right now. And I'll preface this by saying that the book focuses on sound and noise underwater. Noise is actually a technical term. It means unwanted sound that interferes with a signal, so if you're using sound and noise interchangeably, technically speaking, they are different terms. But yeah, I think there are a couple of different ways to go about it.
One of them is to get the data on the animals for different types of sound and understand what that animal hears and what those sounds mean to it. Then when you suggest that maybe there shouldn't be this type of noise in this area or there shouldn't be this type of noise for this long in this area, or maybe don't do scallop fishing in this area in this time of year, you really understand what it is that you're regulating so it's actually useful. You’ll have good data on the animals, what they detect, what it means to them and what impacts aren't as obvious as injury or death.
That's great across a whole bunch of different phyla of animals, and that's a tall order. That's a huge order for sure. That's especially difficult because when it comes to conservation, sound is really important, but climate change is really, really, really important. These impacts all sum on each other, so it's difficult to disentangle them. It's difficult to look at sound just in isolation.
For example, in the Arctic, climate change is making it so that there's less and less sea ice and there's more and more open water, which means there will be more and more shipping in the coming decades. There's a real attention on trying to understand how animals use sound underwater now, before that happens, so that we can make reasonable regulations or something approaching good regulation. That's compounded by the fact that right now, because of the warming water, there are Atlantic species and Pacific species moving into the Arctic and changing the baseline soundscape to begin with. When you start trying to ask these questions in the real world, it gets very muddy and messy, and climate change is a pretty massive part of that.
I think making the mistake of thinking that sound and noise underwater is a single monolithic issue is probably not going to be accurate, because it just isn't. It's usually compounded with other things. Parallel with that is the idea that there are some ways of getting data that people are trying to develop now that will maybe be a bit easier than what we've done in the past.
One of the ones that I talk about in the book is the idea of using soundscape indexes, or using sound to monitor ecosystems as opposed to really labor-intensive fieldwork. In some cases, that can be really useful, because it gets you a lot more data really quickly, and you can get a lot out of that data. It has shortcomings, too. For example, if you're listening to an ecosystem to try to get a sense of how many animals are in the area, you can get a sense of how much noise they're making, but it's really hard to know exactly how many individuals are there.
It's going to give you some things; it's not going to give you other things. But being able to use sound to monitor and measure ecosystems where we otherwise would have no data is also a really interesting area that I think is really cool. There are people working to develop really good soundscape indexes so we can do that.
I ended on the idea of art because I have come across so many beautiful art pieces and sound installations. As we learn more and more about underwater sounds, what we learn is that some of them are just really beautiful. People have always been inspired by this. Songs of the Humpback Whale was a huge album for a reason, right? I think we’re able to bring the sounds of the ocean and marine ecosystems — and freshwater ecosystems, too — into art and public spaces in interesting ways now that we have technology like AR and VR and that kind of thing, but also just as art, to be appreciated and explored by people who are not just scientists.
I think that's massive, because the more we know about these sorts of things, the more we can be amused by it and the more we can hopefully decide that it's something we want to care about and protect.
I love that.
The book is called Sing Like Fish. Where can folks find it, and where can folks find you?
Folks can find the book wherever books are sold. It's on major booksellers and major audiobook sellers. I've checked them all and it seems to be there, so just look for Sing Like Fish. If you can shop local, that's great, too.
You can find me at amorinakingdon.com. I'm on Instagram at @akingdon, and I'm on Twitter at @amorinakingdon.
Thanks for coming on.
Thank you so much.