Mystery Bay

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Hey, I'm Latif Nasser. This is Radiolab day four of our week of sharks. Hello. Hello. And we're starting today with our shark guide in residence, Rachel Cusick, and this lady. I'm Alison Koch. I'm a marine biologist. In South Africa. At a car wash. Oh my gosh, yes. Today, Allison works for South Africa's National Parks, but back in the 90s, young, without a lot of money.

I was a student at the University of Cape Town working at that car wash that you mentioned. It was a small little spot, not one of those drive-through car washes with those like flying sponges. It was all by, yeah, by hand. And my role was to check the cars for valuables and move the cars from the wash basin through to the dry basin. I used to also love just being around water. So that was another drawcard for the car wash. Wow, you're like, oh.

even take the soapy water of a car washes, even if it's not the ocean. And one day, you know, Alison's doing her thing. Wash, rinse, repeat. When one car, it kind of changed her life, this car. Where is this going? How could a car wash change someone's life? Okay, keep going.

So she gets, she like kind of checks for the front valuables, nothing there, nothing in the back seat, but she then goes to the trunk. Dead body in the trunk. Dead body in the trunk, exactly. As she opens up this trunk and inside the trunk are these photographs. They just blew me away. There, in full color, is this image of a shark. This incredibly big, massive, great white shark. Soaring above the waves below. Completely out of the water.

flying fully in the air like an airplane. It was unlike anything she'd ever seen. Absolutely. But... I was quite skeptical. Like you thought they were Photoshopped or something. Well, at the time, Photoshop wasn't. I just, I thought they were fake. You know, I just. I couldn't believe that I'd spent three years at university studying marine biology and not one time did anybody mention flying great white sharks. And so, you know, when the car owner returned to get his car.

Alison asked him, like, what is this photo? Is this fake? And he said, it's real that the friend of his takes these photographs. And I just said to him, look, this car wash will be on me if you introduce me to your friend. And a few weeks later.

Allison is on a boat with that friend. Chris Fellows. And also one of his friends, a guy named Rob. And was there any part of her that was like, they photoshopped this image and now they're kidnapping me? Well, that's what I was saying. Like, very trusting of you to believe these men and go out. on their boat. Looking back, it probably was, yeah.

Anyhow. I mean, it was a beautiful day. It was a flat day and there was very little wind. The sun hadn't risen yet. The sky was totally black. And they were headed out to a place called Seal Island. About a 25-minute boat trip. this massive breeding colony of seals. And as they're getting closer, she starts hearing the sounds of 60,000 seals. You just listen to the seals and you listen to the ocean and the seabirds. Bate.

No sharks. So, you know, Chris kept saying to me, keep your eyes peeled. And him and Rob were really vigilant. And they're staring and they're looking. And the whole time, I still was not believing it. You know, I still remained very, very skeptical. When suddenly Chris shouts, Predation! And right in front of my eyes, Where this little helpless seal is floating. Literally within 10 meters. The water seems to like open up as this giant, giant shark. This incredible animal.

comes flying out from below in the sky. And time kind of like slows down at this point for her. Like, I'm... I'm in shock. Her eyes bulge out of her face and it's just like this massive shark suspended in air. It's like defying every... Not just gravity, it's like defying every version of any shark that she's ever seen, thought about, or learned about in her entire life. It's just like right in front of her. There was no fear. I don't know if it was ignorance. I felt...

Or, I just saw Majesty. I just saw this incredible beauty. And then... The shark lands back in the water. actually moving the boat with the wave from the big splash. And I'm still standing there in complete awe. And I just went, okay, this is me for the rest of my life.

I'm going to study these shocks. And that's exactly what she did. She went back to school, got her master's, then her PhD, and started making more and more trips out there. And what she quickly discovered was, while this is an... Awesome thing to watch as a human being on a boat. One of the days I saw 42 great white attacks. No way! Yeah. If you were a seal on Seal Island, this place was terrible.

I've seen great whites, like, flying out of the water with this seal in its mouth, and the seal is kind of, like, never giving up. Until... Crunch. And, I mean, you're just screaming when you see it happen. That, by the way, is Neil. Dr. Neil Hammerschlag. He's a marine oncologist and a shark researcher. He was spending a ton of time out there, just like Allison. If you saw, like, a lone seal coming back to the island and they're...

like a small kind of baby seal, which would have, you know, smaller claws and not as experienced. Like you would watch it and pull out your camera. I know it sounds terrible, but like you could pretty much be sure I would come. Flying out of the water with this seal in its mouth like minutes later. And Neil started to wonder, like, do these seals register? How awful this place is to be a seal?

Like, do they feel the fear that I can just see so clearly? So I designed the study where we would actually go to the island, get up on the island and collect seal poop. He did the same exact thing on other islands. Islands where there weren't sharks. Then analyze the seal poop for stress levels, stress hormone levels. And what, like cortisol? Cortisol, yeah, like metabolized cortisol.

And what he found was that the seals that live on Seal Island have stress levels that are four times higher than the seals on all the other islands. Wow. Yeah, like quadruple levels of stress. And Neil says you can kind of just see this. The naked eye. Yeah, I mean, in the shallow water, the sharks couldn't really ambush them. So the seals would always stay within five meters of the island. It seemed like the sharks were controlling their behaviors through just...

a landscape of fear, they were causing these seals to not go and do whatever they want or hang out wherever they want or behave any way that they wanted. They were keeping them under control. The way that we imagine sharks, the way that we see them in movies. But they can fly? Like, that is what they were. Something's following us. I can make it! I can make it! To the seals on Seal Island. A tasted human flesh! Oh, God! However... Now you've seen how bad things can get.

And how quick they can get that way. Well, they can get a whole lot worse. For the seals and the sharks of Seal Island, all of that was about to get flipped on its head. And we're going to find a way to get out of here. And we'll get to that. First, we're gonna seal out this room. Right after a break. In the waters around Martha's Vineyard in 1974, they have a 25-foot, 5-tonne problem. It's a great white shark, and it doesn't work.

Celebrating the 50-year anniversary, join me, Tim Harford, for the tale of the movie that should never have been made, Jaws. Listen to Cautionary Tales wherever you get your podcasts. Hey, I'm Latif Nasser. This is Radiolab. We are back with part two of day four.

of our week of sharks. Yay! Okay. Before the break, Rachel, you told us about some high-flying great white sharks, these colossal apex predators terrorizing some poor little seals on an island off the coast of South Africa. Yep, that's right. And we are going to get back to those great whites and those little seals in just a minute. But first, you know.

There are other fish in the sea. We'd been monitoring. Back in 2015, Alison Cock, that shark researcher who got her start because of a photograph she had seen. She received another photo of another kind of shark in the bay, but this one... It was different. Absolutely. Divers sent me photographs of these dead seven-gill sharks lying at the bottom of the ocean. These seven-gill sharks, they're smaller than their great white cousins.

a little narrower. But what struck Alison was that on each of the sharks, there was this huge gaping wound, like the shark had literally been cut and sliced open. And the slice was so clean. It almost looked like a surgical wound. I mean, it was such a clean wound that my immediate suspicion was people that I did it. Yeah. I know.

And that's kind of where we had to leave it because all we had was photographs. But then just a couple months later, another dead seven-gill shark was found by a different diver. And so she's like, please collect it. Please collect it. She wants to do like long order shark view. Shark view. So anyway, they collected it for me and we did the necropsy at the dive shop. And as she's poking around at it.

She realizes, again, it has the exact same wound as the last one did. This clean wound between the pectoral fins of the shark. And that, weirdly... I'm close to inspection. The liver was gone. The liver had been taken out. Just the liver. It's like creepy, like Hannibal serial killer vibes. Yeah. Maybe like poaching or some shady black market stuff. Yeah. I didn't know. But it doesn't end there. And here is where those great whites on Seal Island swim back into the story.

In 2017, Allison gets a call from another Allison, who's another researcher who studies sharks, down kind of like the coast of South Africa. And she's like, Allison, there's this massive great white shark that's washed ashore. Guess exactly what it looks like, Plateau. It's got the same slash. The slash down the body, liver is missing. Everything looked exactly the same. Very weird. I know. And it's about to get...

Even weirder because right around the time Allison hears about this one sliced open great white. The sharks at Seal Island literally disappeared. Again, Neil Hammerschlag. Like they were. Gone. So again, I was like, gosh, you know, what could this be? What's going on? And finally, on the 16th of May, 2022, Alison gets her answer. So, um...

We were contacted by a drone pilot, and he captured the most extraordinary footage. There's no sound, but the video starts with this big, wide shot. looking straight down into this bluish green ocean, maybe like 50 feet below. And right in the center of the frame, you see this shark and this giant, giant white-spotted black orca. For a while, the pair is just eyeing each other, swimming in these tighter and tighter circles around and around.

Until, slyly, a second orca swims into the right of the frame. And the white chalk can only keep its eye on one orca at a time. The second orca starts to slowly glide towards them. until suddenly it darts, slamming the shark, rendering it motionless, turning the water frothy white. A moment later, as the froth fades, the orca swims next to the motionless shark.

This time, baring its teeth, it slices out the shark's liver. Before the clip ends, you can actually even see the orcas start feasting on this white, fleshy pouch. And the shark slowly starts to sink, fading into the blue depths of the ocean. This was unbelievable. Unbelievable. Okay, so it's the orcas who are killing the sharks. Yeah, so these livers of sharks, they're super nutrient-rich. They're really fatty. They actually take up like a third of the shark's body.

And so they are like the creme de la creme for these orcas. They are just this massive meal for them. So they go in and they take the liver and then they actually just leave. Huh. Yeah. I mean, even Alison found this hard to believe. I was in denial for a very long time. Because for me, white sharks were always the apex predator. Oh, wow. Okay, so we're saying the orcas killed all the great whites at Seal Island? Well, it seems like they definitely killed some of them.

And Neil is quick to point out that we humans killed some of them as well. The nets, right? The lethal netting program. Government has had nets in the water to protect swimmers. And something like 30 sharks get caught in these nets and killed every year. Which is a lot for great white shark populations. So that's definitely a part of their decline. Allison would agree.

But here is where things get even more shocking for our apex shark predators. Allison says that for the orcas to clear all the great white sharks at a seal island. The orcas didn't need to kill all of them. Allison and her grad students and some researchers in the area, they had tagged a bunch of these sharks. And when they looked at that tagging data...

They found that after each predation event, you know, each orca attack, took the sharks longer to come back and fewer came back. Until eventually, after about four or five of these predation events that we knew of, the white sharks. stayed away and didn't come back. And so, you know, it's very possible that the fear of predation, the fear of being predated on, made the white sharks. Abandoned Seal Island. But like I can imagine an individual shark getting attacked.

And then leaving or even like if it sees a friend or family member or something getting attacked and then they leave as like a little family unit. But it's not like they have a giant WhatsApp group or something where they're all going to leave en masse. How does that even work? Like a community watch program, but for sure. Yeah. Well, actually, they kind of do. They have this very cool trick.

I mean, sharks aren't stupid. Fear can spread through a population in much the same way as it can through a group of people. I spoke to this man named Colin Brown. He's the head of this fish lab at Macquarie University in Australia. I think one interview called you Dr. Fishfields or something. Yes, I speak for the fish. And he explained to me how fear can spread literally through the water. So if a shark is injured or killed, it releases this chemical.

A very particular chemical, which in the German word is called Schreskopf, which literally translates to scary stuff. Signaling like something bad is happening here. Go protect yourself, like get away. Whoa. And if a situation is bad enough... Treskov can set off a contagion, effectively a behavioural contagion, and an entire population could potentially develop a fear response. Almost like a scream. Echoing through a crowd. Like, it's funny to me that, like, they are the, like...

poster child for scary, especially these flying white sharks. And yet when you get to know them, they are just these little, these little fish that are scared of bigger fish that like, as Colm says, there's always something scarier. Yeah, there's always a bigger fish in the sea, right? And that is virtually true of every animal. The more we find out about fishes and sharks and these sorts of aquatic animals, the more we realise we're basically fish with some tweaks.

Of course, we've come quite some way, but nonetheless, our physiology and our sort of behavioral responses haven't really changed that much. So next time you're afraid of a shark, just remember... They have feelings too.

This episode was reported by Rachel Cusick and produced by Rachel Cusick, Simon Adler, and Maria Paz Gutierrez with production help from Becky Lacks. It was edited by Pat Walters and fact-checked by Diane Kelly. with mixing help and sound design by Jeremy Bloom. And special thanks to Katie Ayers. One more thing, we want to give a big thanks to everyone out there who is a member of The Lab, our membership program.

Your support makes big projects like this possible, makes our entire show possible, and we are so grateful. If you are not yet a member or you've been thinking about giving more, this is a perfect time to take the plunge. join or re-up now, you'll get a gift. It's a limited edition Week of Sharks hat.

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It's available to everyone who joins the lab this month, even for as little as seven bucks a month. You can join at radiolab.org slash join. Existing members, check your email for details. Tomorrow is our last day of the week of sharks. And we are going from some of the biggest fish in the sea to some of the teeny tiniest. Catch you tomorrow.

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