A cooler of eggs and a bold plan to save leopard sharks

Summary

Short Wave Podcast Summary
Episode Title: "A cooler of eggs and a bold plan to save leopard sharks"
Air Date: July 28, 2026
Hosts: Nate Rott, Katerina Barton
Featured Guests: Mardija Sultan (Leopard Shark Nursery), Chelsea Black (Georgia Aquarium)

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Episode Overview

This episode, released during Shark Week, dives into a pioneering conservation effort aimed at rescuing the Indo-Pacific leopard shark (also called the zebra shark in some regions) from the brink of extinction. Through a global collaboration, fertile shark eggs are shipped from aquariums worldwide to Indonesia, where they are hatched and raised before being reintroduced into the wild. The episode explores the science, challenges, and hopes behind this "rewilding" initiative, with on-the-ground reporting from Raja Ampat, an Indonesian marine sanctuary.

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Key Discussion Points and Insights

1. Discovery of the Shark Nursery in Indonesia

[01:06–02:28]

• While reporting a different story in West Papua, Katerina Barton discovers a leopard shark nursery.
• The facility raises shark pups from eggs shipped internationally, aiming to replenish wild populations off Raja Ampat.
• Memorable Moment: Nate reacts to the concept of a "shark nanny."
  • “That is like the coolest title I’ve ever heard. Shark nanny.” – Nate Rott [01:52]

2. The Plight of the Leopard Shark

[02:40–03:34]

• Populations have plummeted by over 80% globally; they're now endangered.
• Main threats: Habitat loss due to climate change (loss of coral reefs) and heavy fishing, especially for shark fins.
• Indonesia is identified as the world's largest shark-fishing nation.
• Quote:
  • “Just the massive decline in populations globally is over 80%, and that’s huge.” – Chelsea Black [02:55]

3. Can a Shark-Fishing Nation Become a Conservation Leader?

[03:41–04:03]

• The episode centers on whether Indonesia can transition from harvesting sharks to conserving them, with implications for global conservation strategies.

4. Leopard Sharks/Zebra Sharks: Misnomers and Biology

[05:01–06:29]

• They are called leopard sharks or zebra sharks, depending on their life stage and region:
  • Young: Black with white stripes (hence "zebra").
  • Mature: Tan with spots (i.e., "leopard").
• Unique feeding habits: They crush shelled prey with specialized jaw plates.
• Memorable Moment:
  • “It’s like C escargot. That does sound really cute.” – Nate Rott [06:46]

5. Conservation Strategies in Raja Ampat

[07:22–08:19]

• Since 2013, shark fishing is banned in Raja Ampat, now a UNESCO Global Geopark known for its biodiversity.
• Still, sharks migrate beyond protected zones, exposing them to fishing elsewhere.
• Quote:
  • “You can't tell them, ‘hey, never leave this marine protected area’... that’s a huge problem in conservation.” – Chelsea Black [08:19]

6. Genetics, Reproduction, and the Need for Intervention

[08:34–09:34]

• Only ~20 wild leopard sharks remained before the project started.
• Sharks mature slowly (up to 10 years before reproducing), making population recovery on its own unlikely.
• Proactive intervention (rewilding nursery-raised pups) is crucial.

7. International Collaboration: The STAR Project

[09:40–10:23]

• The “Shark and Ray Rewilding” (STAR) Project began in 2020, uniting global aquariums and researchers.
• Eggs are sourced globally, genetically screened, and shipped (often via standard couriers) to Indonesia.

8. Shark Rearing: From Egg to Ocean

[11:04–12:20]

• Eggs experience a roughly 77% hatching success rate after shipment.
• Pups grow in the nursery until they're 70 cm long, then transferred to sea pens for acclimation, and finally released at 1 meter (about 3 ft).
• Quote:
  • “So it’s not from here to the big blue ocean... they need to adapt.” – Mardija Sultan [11:52]

9. Monitoring and Successes

[12:20–13:42]

• Released sharks are tagged with transmitters. While they disperse beyond trackers, one shark ("Dana") returned and was found thriving.
• So far, 75 sharks released (16 from Georgia Aquarium), with diver sightings of leopard sharks rising from zero to a 30% chance in dives in the area.
• Quotes:
  • “It’s actually giving us hope... like it’s thriving in the wild.” – Mardija Sultan [12:57]
  • “Divers are seeing them more often in the region… that’s pretty awesome.” – Chelsea Black [13:29]

10. The Future: A Conservation Model

[13:50–14:18]

• Hopes to expand rewilding to other regions and endangered species, establishing a framework for innovative, science-based conservation efforts.
• Quote:
  • “It’s creating a framework for a different type of conservation than people have ever seen.” – Chelsea Black [14:04]

---

Notable Quotes and Memorable Moments

• On the declining shark population:
  • “Just the massive decline in populations globally is over 80%, and that’s huge.” – Chelsea Black [02:55]
• On the importance of conservation intervention:
  • “You have to be proactive about helping the population replenish.” – Chelsea Black [09:08]
• On the cuteness and demeanor of leopard sharks:
  • “Some people call them Labradors of the sea.” – Katerina Barton [06:52]
  • “I don’t really like to give pet-like acronyms to sharks...we should be respecting them as wild predators..but they are friendlier and more docile than you would expect.” – Chelsea Black [07:07]
• On seeing success:
  • “Now we know for sure they’re doing well, at least one. But then the chances, the rest of them…” – Mardija Sultan [13:12]
• On the broader impact:
  • “It’s creating kind of a framework for a different type of conservation than people have ever seen.” – Chelsea Black [14:04]

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Timestamps for Key Segments

• Introduction & Discovery of Shark Nursery: [00:48–02:28]
• Why Leopard Sharks Need Saving: [02:40–03:34]
• Indonesia as Conservation Leader: [03:41–04:03]
• Leopard Shark Basics & Biology: [05:01–06:29]
• Conservation Protections in Raja Ampat: [07:22–08:19]
• Need for Intervention & Genetic Diversity: [08:34–09:34]
• Origins and Coordination of STAR Project: [09:40–10:23]
• Egg Shipping and Rearing Process: [10:29–12:20]
• Tagging and Tracking Released Sharks: [12:20–13:29]
• Early Signs of Success and Expansion: [13:29–14:18]

---

Tone & Final Thoughts

Consistent with Short Wave’s approachable and occasionally humorous style, this episode weaves in curiosity, awe, and optimism alongside clear-eyed science. With a global conservation challenge at its heart, it offers hope for endangered species through innovation, collaboration, and persistence.

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For More:

• Check out related episodes on mangrove trees and fireflies, suggested at the end of the show.
• Learn more about conservation initiatives at major aquariums and UNESCO Global Geoparks.

Transcript

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[Nate Rott]

Nate, Rod here. How are you? No, really, how are you? All right, seeing as this is a bit of a one way conversation, I assume you're happy and fulfilled, but maybe yearning for knowledge, some cool scientific fact that you can tell your friends. Well, that's what we are here for. So please hit follow on whatever app you're listening on so you'll never miss an episode. Remember, knowledge is power. So let's get to the show.

[NPR Announcer]

You're listening to shortwave from npr.

[Nate Rott]

Ahoy shortwavers. Still me hailing to you with former NPR above the Fray fellow and now independent journalist Katerina Barton. Hey.

[Katerina Barton]

Hi.

[Nate Rott]

So it's Shark Week and in honor of that you're bringing us a story all the way from Indonesia about Indo Pacific leopard sharks.

[Katerina Barton]

Yeah. So at the end of last year, I was reporting in the West Papua province of Indonesia for NPR about a totally different story. This area is part of the leopard shark's native habitat which extends to the Philippines and Australia. And while we were reporting, we kind of stumbled across a shark nursery.

[Nate Rott]

Yeah. As one does. Is that like a daycare for sharks?

[Katerina Barton]

Yeah, basically in the nursery there were a bunch of tanks with water pumping through them and they were filled with sharks.

[Mardija Sultan]

This is Maria, she is the senior person here and other ladies are all helping.

[Katerina Barton]

And here we met Mardija Sultan. She's an aquarist and one of the shark nannies.

[Nate Rott]

That is like the coolest title I've ever heard. Shark nanny.

[Mardija Sultan or Shark Nursery Staff]

So this is the eggs of the leopard shark. And this one is the baby just hatch a week ago. And this one egg we are expecting to hatch this big cell.

[Katerina Barton]

And they're raising leopard sharks from eggs sent from aquariums to be released into the ocean off the coast of a group of islands called Raja Ampa. And nothing like this on this scale has ever been done with sharks before.

[Nate Rott]

Oh, cool.

[Mardija Sultan or Shark Nursery Staff]

Erica is a one week old leopard charge and she's coming from Georgia for you.

[Mardija Sultan]

Georgia.

[Katerina Barton]

From Georgia.

[Mardija Sultan or Shark Nursery Staff]

Yeah. Wow.

[Nate Rott]

Yeah, A lot of emergency. So this is an effort to bring wild populations back from the brink of extinction.

[Katerina Barton]

Exactly. Over the past few decades, leopard shark populations have declined to the point where they're considered endangered. I talked about this with Chelsea Black. She's a research scientist at the Georgia Aquarium and focused on their shark and ray research.

[Chelsea Black]

Just the massive decline in populations globally is over 80%, and that's huge. It's very similar, actually, to hammerheads globally.

[Nate Rott]

That's awful. Like, what's causing that?

[Katerina Barton]

It's a few things. Climate change has led to habitat loss, and leopard sharks are a reef shark. So they're dependent on coral reefs.

[Mardija Sultan]

Yeah.

[Nate Rott]

Which aren't doing well anywhere.

[Katerina Barton]

No, they're not. Chelsea says that's another big issue, too.

[Chelsea Black]

And then also fishing. They are most common in the Indo Pacific, which is one of the highest places for shark fishing, for the shark fin trade. So they face a lot of threats just in the region that they are native to.

[Katerina Barton]

And actually, Chelsea said that Indonesia is the number one shark fishing nation in the world.

[Nate Rott]

So today on the show, can one of the world's leading shark fishing nations become one of the world's leading shark conservation nations? And what this project could mean for other endangered species. I'm Nate Rott. You're listening to Short Wave, the science podcast from npr.

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[Nate Rott]

okay, Katarina, I consider myself a bit of a sharkophile. I love sharks, but I know not everyone does. So tell us more about these leopard sharks.

[Katerina Barton]

Okay, first, some people in the US might know them as zebra sharks. And it's funny because these. These animals are known for completely different patterns. One has spots and the other has stripes.

[Nate Rott]

Zebra, leopard.

[Katerina Barton]

Right. Obviously different. Talking to Chelsea, it has to do with how these sharks mature.

[Chelsea Black]

When they're born and they're young pups, they actually look almost black with white spots. So a little more like a zebra.

[Katerina Barton]

They honestly look like giant tadpoles at this point, Nate. Like 20 to 30 centimeters long with big ol heads and a long tail. Whoa.

[Chelsea Black]

And as they grow, their patterns change and they turn to a more tiny, tanned color overall, with dark spots, and then that's more leopard like.

[Nate Rott]

Okay, so as host of this episode, I declare that we should just call them leopard sharks moving forward, just for clarity. That cool?

[Katerina Barton]

Yeah, that works for me.

[Nate Rott]

Okay, so how big are these adults?

[Katerina Barton]

Well, definitely taller than you. They're like eight feet with these round, stubby noses, and their fins are also rounded. They have a really long tail, like I said, and their mouths are kind of underneath their heads.

[Chelsea Black]

Their teeth are different than other shark species, so they actually have more of a crushing plate because they do prefer things with a shell. And they can, you know, crush it up, suck out the inside, and spit out the parts that they don't want.

[Katerina Barton]

And we actually got to watch some of the pups sucking up snails out of their shells.

[Nate Rott]

No way.

[Katerina Barton]

You can see him, like, sucking it.

[Mardija Sultan or Shark Nursery Staff]

So they're using their hold? Yes. No.

[Katerina Barton]

It's so funny.

[Nate Rott]

Wow. So it's like C escargo. That does sound really cute.

[Katerina Barton]

Yeah, they were cute. And they're not aggressive. Some people call them Labradors of the sea.

[Nate Rott]

Katarina, I've been told I give off a little bit of Labrador energy.

[Katerina Barton]

Yeah, I can confirm that. But when I asked Chelsea about it, she didn't seem to agree with that nickname.

[Chelsea Black]

I don't know if I would call them puppy, like, because I don't really like to give, you know, pet like, acronyms to sharks because we should be respecting them as wild predators. But in terms of sharks, they definitely are friendlier and more docile than you would expect.

[Nate Rott]

Okay, got it. So they're chill, but they're still sharks. Katerine, earlier you said that Indonesia is one of the biggest shark fishing nations in the world. So, like, I gotta ask, isn't it dangerous to release sharks there for this conservation project?

[Katerina Barton]

Yeah, it would seem a little risky, but actually, in Raja Ampat, the local government banned shark fishing in 2013, and it became a shark and ray sanctuary. And I actually saw patrols going out to try and catch, you know, people shark fishing. And not only that, but Raja Ampat is a marine protected area and a designated UNESCO global Geopark. It has some of the world's most diverse coral reefs, and some people call it a diver's paradise.

[Nate Rott]

I am so jealous. You got to go there. Like, I want to be a reef shark.

[Katerina Barton]

Yeah, it is beautiful, and the protections are helpful, but one of the problems is that the sharks don't just stay in this protected area.

[Chelsea Black]

So you can't tell Them, hey, never leave this marine protected area, because they just don't know. And that's a huge problem in conservation, is getting sharks and other migratory species to be protected across their entire range.

[Nate Rott]

That makes sense. So now that there's at least some protections in place in Raja Ampat, couldn't the native sharks repopulate on their own?

[Katerina Barton]

Well, when I visited the shark nursery, they told me that before the program started, experts had estimated there were only about 20 wild sharks left in this area.

[Nate Rott]

Whoa. Okay. So, yeah, there would definitely be concerns about the gene pool and genetic diversity and all that.

[Katerina Barton]

Right. That's a big concern. Plus, Chelsea says that sharks are slow to mature. It could take up to 10 years before a leopard shark is ready to reproduce.

[Chelsea Black]

So if you're a shark, the odds of you being caught in a fishery within that time frame is much higher than you are able to reproduce. And so that's kind of one of the reasons that you have to be proactive about helping the population replenish, is getting enough individuals out into the population so that they can start reproducing at a rate that isn't going to continue declining with fishing pressure.

[Nate Rott]

So what I'm hearing her say is it's pretty much a necessary intervention.

[Katerina Barton]

Yeah, that's how they see it.

[Nate Rott]

And, Katerina, you said these sharks are coming from Georgia? Yeah, I thought they just exported peaches. So, like, how did the state of Georgia get involved in a shark conservation project in Indonesia?

[Katerina Barton]

Some of them are coming from Georgia, and they're also coming from Washington, California, and Australia. In 2019, a bunch of conservationists and shark experts gathered at the Georgia Aquarium for a workshop. And the outcome was a collective of research institutions, aquariums, and nonprofits, all with this really big mission in mind.

[Chelsea Black]

This is the first global project to actually focus on the rewilding of a species.

[Katerina Barton]

Their first project, started in 2020, called the Star Project, focused on leopard sharks.

[Nate Rott]

Okay, so aquariums are now sending all of their leopard shark eggs to Indonesia.

[Katerina Barton]

They actually do a ton of genetic testing first to find the healthiest eggs, and then they ship them in coolers to Indonesia.

[Chelsea Black]

They'll just go through regular shipment, like UPS or FedEx or other transport.

[Nate Rott]

Okay, that's not as high tech as I was expecting.

[Katerina Barton]

No, definitely not. And then once they get to Indonesia, the coolers have to go through customs, and they get checked and everything, and then they go to the shark nursery.

[Nate Rott]

And so what is the survival rate of these eggs, like, once they get there?

[Katerina Barton]

Yeah, I asked that same question at the nursery to the shark. Nanny Mardia.

[Chelsea Black]

Is it hard to hatch the eggs?

[Katerina Barton]

Like, will all of these survive?

[Mardija Sultan or Shark Nursery Staff]

Well, that's a really good question. So some of them will survive, some of them will not so far, because egg is like a very fragile stages, but it's also normal. And so far the survival rate of the eggs is about 77%.

[Katerina Barton]

77% of their eggs hatch into little pups.

[Nate Rott]

That's pretty good considering they've been sent from all over the world.

[Katerina Barton]

Yeah, and the Georgia aquarium has shipped 30 eggs since the start of the program. And so far they've released 16 sharks into the ocean.

[Nate Rott]

Where do they go once they've hatched? Like, do they go straight into the ocean?

[Katerina Barton]

No, the pups, the baby sharks, they live in the nursery in these large tanks with ocean water pumping through them. I stood in front of one of them with Marty.

[Mardija Sultan or Shark Nursery Staff]

This is like the second stage before we release them. So we keep it here until 70 centimeter, and then after that we move it to the sea pen. So sea pen is the last adaptation before we release them. So it's not from here to the big blue ocean because they net adapt with the ocean size.

[Katerina Barton]

So the larger sharks go into a pen below the nursery and this is where they'll grow and get used to swimming in waves. And they're finally released once they reach 1 meter long, which is about 3ft.

[Nate Rott]

Okay, so they're getting acclimated to the ocean before they're released. But when they are released, do they know if these sharks are surviving out there?

[Katerina Barton]

The sharks are all tagged with transmitters to study their movements. But, you know, the sharks are now wild so they can swim further away where the program doesn't have receivers to track them. But Mardia and Max Ammer, the owner of this resort where the nursery is, did tell me that one of their sharks named Dana actually came back for a visit five weeks after she was released.

[Mardija Sultan or Shark Nursery Staff]

We measured her, so she's actually growing 7 centimeters in five weeks and gained like 80 grams.

[Chelsea Black]

So.

[Mardija Sultan or Shark Nursery Staff]

So yeah, it's actually giving us for sure, giving us hope. Like actually it's thriving in the wild.

[Mardija Sultan]

It's very important because you don't know if you do everything right, maybe all of them die and you're just wasting your time.

[Mardija Sultan or Shark Nursery Staff]

That's so true.

[Mardija Sultan]

But now we know for sure they're doing well, at least one. But then the chances the rest of us.

[Katerina Barton]

Since the program started, they've released 75 sharks total, including those 16 from Georgia. And Chelsea says there's already some signs that the sharks are doing all right.

[Chelsea Black]

Divers are seeing them more often in the region. They are still pretty rare to see, but the chances, you know, went from zero to, you know, maybe 30% on a dive. You could see one in this region. So that's pretty awesome.

[Nate Rott]

That is awesome. So this resharking effort is working. Like, what does this mean for the future of conservation programs like these?

[Katerina Barton]

Well, Chelsea says that they hope this initiative will help downgrade leopard sharks from endangered and not just here in Indonesia, but all over their larger range. And then they can start thinking about other endangered species of sharks.

[Chelsea Black]

The thought of expanding to more than just the leopard sharks and more than just Raja is incredible. And I think it's creating kind of a framework for a different type of conservation than people have ever seen.

[Nate Rott]

This is all so cool. Katerina, thank you for bringing us this reporting.

[Katerina Barton]

Yeah, it was my pleasure.

[Nate Rott]

All right, if you like this episode, you'll probably like our episodes on the superpowers of mangrove trees and the magic of fireflies. Give them a listen. This episode was produced by Rachel Carlson, edited by our showrunner Rebecca Ramirez, and fact checked by Tyler Jones. Jimmy Keeley was the audio engineer. I'm Nate Rott. Thanks for listening to Short Wave from npr.

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