In this episode of the "How to Protect the Ocean" podcast, host Andrew Luen discusses a remarkable predation event that occurred in 2014 in the Barents Sea off the coast of Norway. During this event, approximately 2 million Atlantic cod consumed around 10 million capelin, which is nearly 50% of the capelin population present at the time.
The episode highlights how this massive predation event was observed using advanced technology, specifically the Ocean Acoustic Waveguide Remote Sensing System (O-A-W-R-S). This system allowed scientists from MIT and Norway to detect and analyze the behavior of the fish during the capelin's spawning season. As the capelin swam deeper to avoid sunlight, they formed a large bait ball, which measured about 10 kilometers long and contained around 23 million fish.
The podcast emphasizes the significance of this event as it represents one of the largest predation interactions ever recorded. The coordinated attack by the cod and the formation of the bait ball illustrate the complex dynamics of predator-prey relationships in marine ecosystems.
Additionally, Andrew discusses concerns regarding the impact of climate change on these fish populations and their spawning behaviors. He raises questions about the sustainability of such large predation events in the future, considering the potential effects of environmental changes on both capelin and cod populations. The episode concludes with a call for listeners to engage in discussions about ocean conservation and share their thoughts on this fascinating topic.
Link to article: https://www.theinertia.com/environment/oceans-largest-predation-event-ever-seen-recorded-by-oceanographers/
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Here's a fact. COD-EAT-CAPELINE. It's a pretty known fact. That's the main predator of CAPELINE, whether it's on the east coast of North America, especially in the northeast coast, or if it's off the coast of Norway in the Atlantic. COD-EAT-CAPELINE. But just imagine how much, because today we're going to be talking about one of the biggest predation events ever witnessed. It was back in 2014. So almost 10 years ago, where 10 million CAPELINE were eaten by 2 million COD. Imagine witnessing that. Imagine seeing that for the first time and really thinking about, how does this happen on a regular? How does this happen where it sustains the population? Well, I'm going to tell you how, and I'm going to tell you that the entire population of CAPELINE in that ball during that event was 23 million. So just under 50% were eaten. But does this happen often somewhere else? And what's going to happen with climate change? How is it going to be affected? And is this a problem for CAPELINE in the future? We're going to be talking about that all in today's episode of the How to Protect the Ocean Podcast. Let's start the show. Hey everybody, welcome back to another exciting episode of the How to Protect the Ocean Podcast. I'm your host Andrew Lewin, and this is the podcast where you find out what's happening with the ocean, how you can speak up for the ocean, and what you can do to live for a better ocean by taking action. If you're here now listening to this podcast, or you listen to it any number of times, or if this is your first episode, this is the resource to find out everything that's happening with ocean conservation and ocean science around the world. This is the place you are in the right place. You can find more information on what's happening around the world of in ocean conservation, by going to SpeakUpForBlue.com. That's SpeakUpForBlue.com. And if you want to find out how to get information to your inbox Monday to Friday, so having three news articles, the latest podcast, the latest videos that we put out, as well as the latest job posts that we find on the internet, you can sign up for free by going to SpeakUpForBlue.com/newsletter. That's SpeakUpForBlue.com/newsletter. Let's get into the show, the ocean's largest predation event ever recorded by oceanographers. And it wasn't by a whale, it wasn't by a shark, it was by cod. It was by Atlantic cod, eating their main prey diet, Caplan. And in this study that was just published recently, oceanographers from MIT and Norway published a study after observing a staggeringly large predation event. So in 2014, in the Berensea, off the coast of Norway, over 10 million fish were eaten in just a few hours. So how in the world does that happen? Well, it happens during, maybe just after Caplan's sort of spawning event. So essentially what happens is the Caplan come in and they start swimming on their own. They're just chilling, they're swimming on their own. And after a while, they start to dive deep. And they dive deep. And as they dive deep, they get closer and closer together. And then more get closer and closer together until they form probably the largest bait ball you've ever seen. Now, Caplan are used for a number of different things. They are used for fish bait. They're used for as fertilizer, they're used as food, as a food source for select communities. And so they're, you know, they're used quite a bit, but they do tend to have these bait balls. And a lot of times you'll see it. They're very like anchovy-like fish. So they're very small. They're probably about this big. They're arctic fish. They're normally in the North Atlantic or in the here in the Berensea. And they like the cold water. They like to dive deep. They like to be in a bait ball. Why do they go in this bait ball? It's to protect themselves. So the fish in the middle will be protected from predators from the outside. And the fish on the outside are a bit altruistic, meaning that they're probably going to get eaten. It was a good chance they're probably going to get affected, damaged, you know, hurt in some sort of way, or just eaten in general, because they're on the outside of this massive bait ball. Now, when I say massive, I'm talking about 10 kilometers long. That's how big. That's how much like 23 million fish in one area, 10 kilometers long. That's how many there were. And 10 million of those were eaten by approximately 2 million codfish. Now you're probably like, how do you count all of those, Andrew? Like, that doesn't make sense. You don't want to just have someone just counting all the fish. No, this was done by a specific instrument that's called the Ocean Acoustic Wave Guide Remote Sensing System. So the OAWRS, I don't know if it's called OARS or what have you scientists, we love our acronyms, right? But it was recorded a decade ago during an exploratory trip where a team of scientists were used as sonic imaging technique known as the Acoustic Wave Guide Remote Sensing System. This acoustic array attached to the bottom of the vessel, where it sends sound, sound waves on all directions. Those waves are bounced off anything and everything in their path. So if there's fish in the way or there's anything it bounces off. Now, like another set of acoustic receivers picks up the reflected sounds, giving the viewer an idea of what's happening for miles around. So it's on a screen. It's almost like how they do seismic surveys. When they send an acoustic sound to the bottom of the ocean, it bounces up and depending on how it hits and how it reflects back, you get to see these pockets of sort of like hydrocarbon pockets, right, where you want to see oil and gas. In this case, you're seeing fish. Now, how do we tell between different species of fish? Well, it just happens, so happens that cod have swim bladders. The swim bladders allow them to float in the water column, so they're not always sinking like a lot of these sharks. But you have the swim bladders. Cod have bigger swim bladders than the capelin. So when a cod has a low resonance, right, like a big Ben Bell, whereas capelin have tiny swim bladders. So the resonance tends to be a high-pitched notes like piano. So you get the difference in the pitches as they come back and the computer is able to decipher between those pitches. And if you just do a little bit of programming or MIT people here, I'm not sure what background the people in Norway have, but the MIT people have this coding experience and they're able to decipher between show how big these bait balls are, how big the population of each of these different species are. So that was kind of cool. So the MIT paper goes on, I'll link to the article in the show notes, but the MIT paper goes on to explain that the data was collected during the very heat of capelin's spawning season. So as the array pinged off them in the early morning hours, they were seen to be moving mostly as individuals along the coast of Norway. As the day progressed, however, they swam deeper, perhaps in an effort to avoid the light of the rising sun, so they're not seen. But I think this is a quote from I don't know who, but one of the people, it says the team observed that as the capelin descended, they began shifting from an individual to group behavior, individually forming a huge shoal of about 23 million fish that moved in a coordinated wave spanning over 10 kilometers long. That is huge. I would love to see like sort of like a bait ball that much or that much of a shoal of fish, because that's just cool. A shoal fish is essentially a school of fish, but just in the large area, very compact. As soon as the master shoal began swimming as one, a behavior seen in other fish and some flocks of birds. So just imagine a flock of birds as they switched directions, they all switched directions. And the cod in the area responded, forming a shoal of their own of over two million strong, the cod began systematically attacking. Macris, who was one of the scientists on the study, is the first time, he says it's the first time seeing predatory prey interaction on a huge scale and it's a coherent battle of survival. So this is happening over a monster scale, monster scale, and we're watching a wave of capelin zoom in, like a wave around a sports stadium, and they kind of gather together to form a defense. It's almost it's also happening with predators coming together to coherently attack. This is unprecedented. We've never really had the chance to observe such a large scale predatory event like this. We've seen bait balls before, never in the 10 millions that we've seen. So this is great to be able to have this data in now. What we worry about in the long run is how these bait balls are going to be affected by climate change. We know fish spawning, we know currents changing, climate change, it all gets affected with climate change, right? So heating of the oceans, switching of currents and wind patterns in the in the ocean and in the atmosphere can really change how things are done, you know, and how things work and function within the ocean. You know, it's these small fish when they're larvae, they get taken by the currents to another place, and that that pattern is dependent on dependent on by predators and prey itself to run their regular life cycle. As those change during climate change or throughout climate change, this will change the pattern and may affect whether short term or long term, whether it's going to be cabling success in reproduction or the cod success in predating these fish, this prey, right? This cabling. So it could be a problem when we see these massive bait balls. As you know, the team said, the study team said, it's like, once we get the last bait ball and we know it's the last population and we know it's going to be a mass, you know, feeding and predation population event, once they're gone, they're gone. If they don't recover fast enough to take on, you know, 10 million or however many get, get eaten at that one time, that bait ball, that population will not recover in time. It is dependent on numbers. It's a numbers game. So if those numbers aren't successful in, in, in having 10 million more offspring or more of that or less, if it's less, then we know that the cod population is going to go down. So that's, you know, these, and other predators that depend on cabling as well, it's all going to be affected. It's all on a food web and it's all negatively responding or positive responding depending on how much reproduction we see on a daily basis, on a annual basis, semi-annual basis, you know, every couple of years. This is the problem with climate change. This is the problem with any kind of environmental disturbance that we see is will we have more cabling to be able to witness these massive feeding events? I don't know. I haven't read the full study yet. I don't know if there have been other events after that that are that it shows a pattern of these massive 10 million, this 10 million feeding event, but that's pretty cool. That's pretty cool to see it and be able to recover after that. So hopefully we'll see more recovery. I know in certain places like off the coast of Canada, cabling are in a critical point as well as cod is just over a critical point, but like slightly. And, you know, there's been an increase in fishing for cod, Atlantic cod off the Atlantic coast of Canada. And so there's an opening of that. That could be dangerous as well. So these fish populations are not, you know, they're not unlimited. There is a limit to each one. They can go down in population, depending on what happens, climate change is rearing its ugly head faster and faster than we've ever seen. So we don't know how this is going to affect this fish population. I'll try and get more information and maybe try and get an interview to talk about the the cabling, cod, predation, prey relationship on that side of the Atlantic and be able to bring that back to you. But I thought it was an interesting story. I wanted to bring it to you because I think it's something that we should share together. And I'd love to hear your thoughts on it. Do you have you ever heard of this before? Have you ever seen any more studies who's working on this? I would love to hear and what you think of the content of the topic of this 10 million strong bait ball, 23 million bait ball, but 10 million being consumed in less than a few hours. I think that's amazing. I want to hear your thoughts. You can hit me up on a comment on Spotify on YouTube or you can hit me up on Instagram at how to protect the ocean. Just send me a DM that's at how to protect the ocean. I would love to hear your thoughts on the podcast. This thoughts on this episode and just your thoughts in general is relating to ocean conservation and science. Feel free to contact me, ask me any kind of questions that be more than happy to answer it either here or to you directly. I want to thank you so much for joining me on this episode of how to protect the ocean podcast. Have a great day. We'll talk to you next time and happy conservation.
