John Ryan: Humpback whales, they’re an amazing story in their own right. They can produce songs that span more than nine, octas more than a piano, including song sounds that reach right down to the lower limit of our hearing, and even sounds that extend above the upper limit of human hearing. Humpback whales are just the most phenomenal composers I have could ever imagine.

Mike DiGirolamo: Welcome to the Mongabay Newscast. I’m your co-host, Mike DiGirolamo, bringing you weekly conversations with experts, authors, scientists, and activists, working on the front lines of conservation, shining a light on some of the most pressing issues facing our planet, and holding people in power to account. This podcast is edited on Gadigal Land. Today, on the Newscast, I speak with John Ryan, a biological oceanographer with the Monterey Bay Aquarium Research Institute. His team conducted a multi-year study that examined the songs of Baline whale species in the California current ecosystem. The study Ryan explains found that whale songs rose and fell along with food supply. In this conversation, Ryan explains to me, why this happened and what it tells us about the health of baling whale species in changing ocean conditions while providing a window into how some whale species may be more vulnerable than others, particularly with changing foraging conditions for krill, Ryan emphasizes that the science helps inform management and protection of whale species, including providing information for shipping companies to reduce whale strikes and rewarding conservation efforts. Ryan was kind enough to share some of his recordings with us, which provide a haunting glimpse into the world of whales. John, welcome to the Mongabay Newscast. Thanks for joining us.

John: Thanks for having me, Mike.

Mike: So first can you tell us, tell our audience what your team discovered using Bioacoustics? Can you give us a short summary of what it was that you found?

John: We discovered that how much baleen Whale Sing depends strongly on how well the ecosystem is feeding them and. That’s the ecological knowledge that was gained. Yet what this research did was to answer a longstanding question that resource managers have, which is, can we just listen to whales and know how many of ’em are here? And this research resoundingly answered, no, sorry, it’s more complicated.

Mike: we can get, and we’re gonna get into the complex part about that. But I guess for the average, listener why is this research so important? Go into a little bit more detail. What is this really telling us about Whales?

John: all of our research about whales in this region is about supporting the recovery of populations that were decimated by whaling. We can only do that if we understand where, when, and how they live and how our activities intersect with their lives. in this case, the idea that resource managers need to know local population density, they need to know what, aspects of the ecosystem influence their lives and their behavior. This very fundamental ecological research gives us a window into their lives. One of many windows that. We open ultimately through the application of technologies.

Mike: And what are you learning about the changing ocean conditions and how animals, in this case, whales are adapting to this? our listeners all hopefully know by now that our oceans, they’re heating up. But from what I understand in your report, at the height of a marine heat wave in 2015, whale songs from both Blue and humpbacks were at their lowest levels. So can you explain why.

John: Yes, that’s right. We began recording nearly a decade ago. In the summer of 2015, which was happened to be the peak of a major marine heat wave that impacted the entire Northeast Pacific. And from the perspective of a whale, there were really two primary impacts. Food resources were low in abundance, relatively depleted, and also the food web was toxic because the unusual ocean chemistry. Accompanied the heat wave contributed to a massive bloom of toxin producing algae. And it is documented as the largest scale of poisoning of marine mammals by this potent neurotoxin called deic acid ever observed. They were hard times for, whales and many other animals. Not just marine mammals, but also seabirds who were starving and being poisoned. And so your emphasis on environmental changes is highly relevant here. In a way, what the marine heat wave gave us was a, an opportunity. To view not just an extreme state that can develop in the ecosystem, but also a potential view of the future if these marine heat waves increase in frequency or severity.

Mike: And so what did you notice about how whales were reacting to these changing ocean conditions? What gave you insight into that?

John: fortunately, we are able to record sound continuously through a cabled observatory, which provides real-time connection to the deep sea and unlimited power in communications. So, by being able to listen continuously over six years in this case, we were able to quantify for the first time. How much song detection varied for yes, as you mentioned, blue whales and humpback whales. And yet the study also included fin whales and all three whale species showed by far the lowest occurrence of whale song that was recorded during the entire six-year period. And whenever you see such large changes, and by large more than doubling. For two of the whale species over the six-year period, changes of a factor of two, which is a lot within a year. And that was the first key contribution. How much does it vary? And when you observe these very large changes from year to year, there are many possible explanations for that change. And that was really, I think, the key to this study. It was in fact more data and more diverse data than I have ever worked with in a single study. And that’s based on doing research for the last 30 years. And so, for example, the simplest explanation for a change in the amount of whale song you hear could be the number of whales that are present, the number of singing whales specifically. And you might think that it’s hard to evaluate that hypothesis. How can you know how many whales are out there? That’s where this study took advantage of ecotourism, whereby people are out on the water every day in multiple boats both for whale watching and for doing research. And everyone who sees a whale can photograph its fluke. And those photographs are like a fingerprint, the shape, and the coloration of a whale fluke, particularly for humpbacks is used very reliably to identify the individual whale. And there’s a system called Happy Whale that you can find online where anyone can contribute their photographs and ai, a machine learning system identifies the individual. Now the reason that’s so important to this study is that by knowing the unique number of, in individual whales that we’re seeing every day, and by being able to evaluate how long certain individuals are staying in the region, we can address a number of alternative hypotheses. Were there more whales? Did the whales stay longer in this ecosystem between their breeding habitat migrations? Did individuals have a stronger affinity site fidelity for this location, Monterey Bay? We could answer all those questions. And I. beyond the questions about the whales are questions about our ability to detect their songs for example, the physical conditions of the ocean change from year to year, and that changes how sound propagates from a whale to our microphone. Our, hydrophone and we were able to model sound propagation through the ocean and evaluate that as a possible factor in the changes that we heard. We monitored the wind speeds because wind creates background noise that can mask our ability to detect the whales, particularly humpbacks who sing in the wind noise range. And so we were able to evaluate that hypothesis. And after considering all these alternative explanations, the one that stood strong throughout the whole study period and for more than one whale species was that they significantly change how much they sing from year to year based on how well the ecosystem is feeding them. The only way we could really assess that is to know the whales diet. So yet another data set where tiny skin samples from the whales can be examined for. Isotopes of carbon and nitrogen and, that data tells you what have the whales been eating? And that confirmed the changes in their diet that were predicted based on measurements, observations of the forward species that sustained these whale populations. So I know that was a really whirlwind tour of all the data sets, but each one of those was really necessary to keep our ideas and our hypotheses open and truly consider all possible explanations.

Mike (narration): Hey listeners, thank you for tuning in. As always, if you happen to listen to us on Apple, you can find us now on the Apple Podcast app quite easily by going to the new climate category. Scroll down to the new and noteworthy shows. I. And find us there. And also, please subscribe. Doing this helps let Apple know you value nonprofit environmental outlets like ours. But another way you can support us is by donating to us using the donate button@mongabay.com. That’s all for now. Back to the conversation with John Ryan.

Mike: Something that I thought was really interesting was that at a certain point it looks like humpback whale songs continue to increase each year while Blue Whale ones did not. Do I have that correct?

John: You do have that.

Mike: What caused that?

John: Yes, the clearest explanation for that was traced back to the Ford species that the whales rely upon, and an important distinction between. Blue whales and humpback whales, specifically blue whales only eat krill, the small shrimp like crustaceans. And so if krill abundances are low, blue whales have only one choice. They have to search farther and wider to find the krill that they need to sustain their massive bodies. they are. More flexible. They can switch their diet from krill to fish, depending on which food resource is more abundant and available. And that’s exactly what we saw in the isotopic composition of the whale skin samples across a two-year period. The third and the fifth study years, we noticed that there was a shift from the away from krill as the dominant forge species available. The forging resource available to the whales over, to over to fish, small schooling, fishlike anchovies. In fact, anchovies were the dominant fish or fish that were available to the humpback whales. So, what happened across that two-year period is that krill plummeted in abundance and fish skyrocketed in abundance. So, we could see in the whale skin samples that the indeed the blue whales were searching farther and wider throughout the region to find the food they needed. And in contrast, humpback whales switched from a diet that was mixed. It included both grill and fish. When the fish population skyrocketed, their isotopic compositions indicated they were exclusively eating fish and persistently eating fish. So that kind of defines, in a sense, resilience. I. I think all the whale species that we studied are resilient because they’re still here. They can handle these dramatic changes in their ecosystems, and they can carry on. But humpback whales have the advantage of this greater flexibility switching between the dominant prey that are available depending on how the ecosystem changes. And so that is an advantage, and that’s because we could see the humpback whales adapt in their diet and because across those same two years, we were seeing humpbacks less while hearing them more. That is to say fewer humpbacks seem to be in the region, but we heard song more days. That indicates a behavioral change how much they were spending time and energy singing rather than searching for food.

Mike: And I think it’s worth pointing out here for listeners, and we will play you audio of this, but blue whale sounds are not audible to the human ears. So that, if, I have that correct, so how did you detect that sound?

John: The hydrophone that we use captures sound from below the lower limit of human hearing to about five times above the upper limit of hearing. So the, sound itself is measured very accurately across a dynamic range that is well beyond our senses. And so, what we do is simply analyze that audio data to reliably detect, classify, not just the sounds produced by these whales, but very specific sounds. These are the sounds that are the, most they’re the primary sounds that we hear in this ecosystem by far, the most abundant acoustic signal we could use to detect their presence. And when it comes to a listener hearing a blue whale, it’s a combination of factors. Some of the sounds that the blue whales produce are truly below the lower limit of hearing, but if you had the right speaker in the room. You could feel it in your entire body, even though your ears per se wouldn’t be the primary sense, your lungs would become the primary sense as that air moves and vibrates your entire body.

Mike (narration): John supplied me with all the audio files you’re about to hear. Here’s one from a blue whale at 48 kilohertz. Humans normally can’t hear this. The audio has been sped up five times.

John: Some of the higher harmonics though, produced by the blue whales can be heard by our ears and with the right speakers. it still requires speakers that are capable of turning that. Acoustic signal into an acoustic wave that you can sense. And for example, the primary call of the blue whale that we studied has it has two harmonics that most speakers cannot touch. Your computer speakers, your phone speakers would not respond at all because the frequency is simply too low for that technology. But some of the higher frequencies, you would begin to hear them on, very simple speakers. In contrast, I bring a 200 pound suber speaker on the road pretty regularly so that people can feel the fullness of multiple harmonics produced by these massive blue whales. humpback whales, they’re an amazing story in their own right. They can produce songs that span more than nine octaves more than a piano. Including song sounds that reach right down to the lower limit of our hearing and even sounds that extend above the upper limit of human hearing. Humpback whales are just the most phenomenal composers I have could ever imagine.

Mike: Something that really fascinated me is that. the, “krills up” call that blue whales make apparently are understood by humpbacks. Now, to me that’s really remarkable because that’s like interspecies communication. What, can you talk about the significance of that?

John: Yes, that’s right. We talked about that idea where, let’s go back to blue whales to begin with. Now, the blue whale D calls are not part of their songs. They’re produced specifically when blue whales are foraging. And what we learned in a different study is that blue whales put out those D calls at an exceptionally high rate when they’re coming together in large forging aggregations, for example. This study led by David Cade, when he was a graduate student, observed up to about 40 blue whales within a one kilometer square area, which is a tremendous number of blue whales to fit in one place, but they were there because the forging conditions were exceptionally good. Massive krill swarms that. No one whale, no 40 whales could quickly or readily deplete. Therefore, our interpretation from that study is that the decals are like an acoustic signpost, whether they’re intentionally produced for that purpose, I. Or unintentionally, it seems to be how they function because when a blue whale produces a D call, it can be heard by other blue whales easily up to 50 miles away, and blue whales can move very quickly and take advantage of that knowledge that there’s a, there’s an active forging site that they can take advantage of.

Because they must find very dense krill swarms in order to survive. The effort that they put into foraging is quite tremendous in itself and it’s only worth it if in every lunge that whale can take in a lot of energy from a dense swarm of krill. So that’s the context for blue whale foraging ecology.

Now, onto your question about how humpback whales might take advantage of that. In the study we’ve been focused on what we noticed is that when humpback whales were forging on krill, they were in the same place in time as blue whales forging on krill. And so it was, speculation and it remains speculation that if humpback whales have learned to recognize that a blue whale decal means a great forging opportunity for krill, and if they move to the forging hotspot and take advantage of those krill, it would make sense. Evolutionarily, they’ve had millions of years to figure it out. And it would be a tremendous benefit to the humpback whales to take advantage of that signal across the species boundary and tap into the wealth of knowledge that the ocean soundscape contains. And I, since we’re talking about speculative ideas, what we’ve, one thing we’ve been absolutely fascinated by is that. Blue whales produce a relatively few number of calls, four of them in this region, and one of them sounds like a heartbeat, and it’s a heartbeat within the range, I should say. The pitch of that sound is within the range of human hearing, so we could hear that on ordinary speakers. And what we’ve noticed is that humpback whales, they’re such, they’re free in their compositions and I’ll sometimes hear them making a sound that. Almost sounds like a blue whale. A call, like a heartbeat, but it’s got a little too much. Humpy in it like a humpback. They just have a certain way of making sounds. But over time, that humpback whale dials into what is much more like the heartbeat, pulse of the actual blue whale call, and it would make perfect sense. They’re bathed in a world of sound. They transmit their learned songs culturally, constantly changing up the songs when they hear new ideas, for example, from other humpback whale populations that they encounter along their migration routes. So why wouldn’t they incorporate a beautiful sound made by another species into their own songs? So yeah, this idea that Interspecies information can travel or that information about the ecosystem can travel between species is very realistic because these animals do use the same frequency range and presumably they can hear in the sound range that they produce, so that information should be available to their senses.

Mike: I just wanna connect the dots a little bit for our listeners, and I think you’ve already touched upon this a bit, but so it, it looks like. Krill, blue Whales food source changed quite a bit and there wasn’t as much for them to, forage on. Was the reason behind that global heating was that the primary reason why that changed so much?

John: The direct reason was the presence of this massive marine heat wave that ultimately spread throughout just a tremendous area of the Northeast Pacific. And it may have had contributions from a tropical phenomenon known as El Nino. And it lasted a few years. It was really a major strong and long enduring impact on the ecosystem. And what I’m hearing from you is maybe another question. Are these heat waves being driven by a. Global climate change and will these marine heatwaves that are quite detrimental to marine life, will they become more severe, more prevalent? And that I think is an open research question. Yet what is absolutely certain is that the ocean heat content has been rising for decades and it’s been rising because heat is being trapped in our atmosphere. We can measure sea level from space. And sea level is a phenomenal record of that heat content in the upper ocean, and we’ve been measuring that with tremendous accuracy. Imagine flying over your city at the height of your typical flight, say 33,000 feet. Being able to measure the thickness of a dime sitting on the sidewalk. That’s how well we can measure sea level. And that’s how why we are so confident in our understanding about these global scale changes. They differ from region to region, but globally that heat content of the ocean is rising. And on first principles alone, that is likely. To influence the occurrence, the severity, the prevalence of marine heat waves.

Mike: So, at the beginning of our conversation, you said that you know this is going to help researchers project or at least predict about things that could occur down the road. So can you give us sort of a high-level overview of what are some of those things that this can now help us predict and point to?

John: That’s a great question and your question is, in my mind, has the context of the, relative resilience and the relative vulnerability of different whale species. So for example, in our region I. Of the three whale species studied blue fin and humpback. Blue whales by far have the smallest population size. They have the, in, in that sense, their recovery from depletion by commercial whaling is earlier in, it’s in its process. They just, they’re in. A smaller population simply is at higher risk. And so, our study sort of amplifies that concern or that vulnerability in the sense that, humpback whales, which are a strong contrast with their flexibility in foraging, give them, it gives them a greater ability to adapt, to change. For example, if the prevalence of marine heat waves continues to increase and intensify and that. Strongly influences krill populations more so than fish that will make blue whales yet more vulnerable and in the sense of management a higher priority for protection from the various threats that they face. These threats include interference with their lives from the noise that we put into the ocean. And really the biggest one being struck by ships. And this is where our research program, which is focused on science for conservation, has had a really, in my mind and in my heart, a heartwarming success. So, there’s been a longstanding concern about. Whales being struck by ships in our region. Even though we’re a national Marine sanctuary, there are just places where the ships paths cross important forging habitat of the animals. So, the risk is simply elevated. And some of the research we did, tracking the movement, ecology of blue whales helped our sanctuary. To be motivated to act on this long-term concern about ship strikes and to join a program that is called Protecting Blue Whales and Blue Skies. It’s a partnership that spans research, resource management, and industry. Specifically, it’s a voluntary speed reduction program where massive ships that are three football fields long, including the end zone moving fast through the ocean. They wouldn’t even necessarily notice if they hit a whale, but, it would be fatal for the way up. And now we have a. Right here in the sanctuary and in the sanctuary to the south of us and north of us. This program, really brilliant program is being so highly effective at slowing down ships, which has multiple benefits. It reduces the risk of whales being struck and killed by a ship by more than 50%. It reduces the noise radiated from the ships underwater, which creates a better and safer acoustic communication space for the whales. It reduces air pollution from the ships, and it reduces fuel use. So economically, it’s a benefit to the shipping companies. And I just came back from a conference in Los Angeles where we were thanking. The people from the shipping companies, we were asking them, how can we analyze data that will help you understand your positive impacts? And I brought my 200-pound subwoofer and I rattled a warehouse at the end of the award ceremony with the voice of a blue whale. And to me, it felt like gratitude emanating from the whales themselves. To people who are consciously choosing to make changes that will support the recovery of this endangered population.

Mike: That’s actually a really good segue into my next question. I’ve read that whales. Make specific sounds or little squeals when they’re excited or happy. Did you notice any evidence of whale’s emotional state during this study? And was there a specific time where you could tell that they were probably happy?

John: I’ve listened to a lot of whale song. Both the kind you can only hear with a subwoofer and the kind you can hear through ordinary speakers and I, when I share these recordings of whale song publicly, I find that people can respond emotionally very readily. It’s natural. And yet ultimately when I listen to that whale song, how I feel is it’s a reflection perhaps as much of my state and my love of the animals as it is of the animals themselves. It’s hard for me to fathom the nature of and the ways in which they experience sound, the ways in which information may be communicated through the collections of sounds that they create and produce. Yet there is one. There’s, in relation to your question, there’s really one pattern I’d like to highlight, and it’s a seasonal pattern because in fact, the presence of the whales in this ecosystem is phenomenally seasonal, and that’s because the winds over the ocean are strongly seasonal. Specifically, the winds drive upwelling of deep nutrient rich water on an annual basis that starts in the spring and ends in the winter. And that upwelling brings nutrients to the surface, which allows microscopic algae in the surface sunlit layer to transform non-living matter into living matter and fuel the entire food web. And that very same wind driven upwelling causes changes in the behavior of forged species, including krill and anchovy that these whales rely upon, and specifically the forged species form dense aggregations, which makes the forging effort of a whale much more efficient, much more successful. And when I listen to the songs of Whales, I also hear this very strong seasonal pattern where early in the season it feels like the songs, they’re working on are somewhat experimental. They’re and like maybe some of the younger whales just starting to figure out how to sing are really going for it. And then we’ve measured this. As we get into the fall from late summer into fall, especially humpback whale songs become longer and more complex, like they’re building up their performance for the highlight, which is the breeding habitat where song is, at its peak. So, I feel like there’s definitely every year a. A developmental process that the population goes through as they create a new song that they share and develop it to higher levels of complexity and beauty.

Mike: My last question to you is there something you wish more people knew about whales in general?

John: It’s hard to feel a connection to an animal that lives most of its life underwater under the sea, and I wish more people could feel a sense of connection to these really magnificent beings. And if that means getting out for a whale watch and seeing the acrobatics of a humpback whale as it launches 70,000 pounds of body mass out of the water, that’s one wonderful way. Yet, even from a landlocked place, you can tune into the voices of these animals. And really there’s just no, no substitute for hearing the sound produced by another living being to give you some sense of connection. And we can only care for something. And we can only find a sense of caring within ourselves if we feel some connection to it. And I think sound naturally does that for, whales especially. And so yeah, that would be my hope that people take a moment to connect with the whales through their voices.

Mike: John Ryan it’s been a pleasure speaking with you. Thank you for joining me today.

John: Thank you, Mike.

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Mike (narration): This episode is dedicated to our East Africa editor, Ochieng’ Ogodo. See the show notes to learn about his life, legacy and achievements. if you want to check out the study from John Ryan, you can find a link in the show notes as well as an article from Staff writer Bobby Bascomb. As always, if you are enjoying the Mongabay Newscast or any of our podcast content and you want to help us out, we encourage you to spread the word about the work we’re doing by telling a friend and leaving a review. Word of mouth is the best way to help expand our reach, but you can also support us by becoming a monthly sponsor via our Patreon page at patreon.com/mongabay. Mongabay is a nonprofit news outlet, so when you pledge a dollar per month, it makes a big difference, and it helps us offset the production costs. So, if you’re a fan of our audio reports from Nature’s frontline go to patreon.com/mongabay to learn more and support the Mongabay Newscast.

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