- A rewilding project aimed at saving endangered zebra sharks (Stegostoma tigrinum is sending eggs from aquarium sharks more than 12,000 kilometers (7,500 miles) away to nurseries in Raja Ampat.
- After hatching, the young sharks are kept in tanks until they are strong enough to release into the wild.
- Researchers hope to release 500 zebra sharks into the wild within 10 years in an effort to support a large, genetically diverse breeding population.
- A survey estimated the zebra shark had a population of 20 spread throughout the Raja Ampat archipelago, making the animal functionally extinct in the region.
RAJA AMPAT, Indonesia — Nearly a million people visit the Shark Reef Aquarium on the Las Vegas Strip in Nevada every year. There’s a chance they see zebra sharks (Stegostoma tigrinum) among the more than 15 shark species roaming the aquarium. But they might not be aware that those zebra sharks are a part of a rewilding project that tries to save the shark from extinction — the first of its kind in the world.
In 2023, eggs from the aquarium sharks were shipped more than 12,100 kilometers (7,500 miles) to the Raja Ampat archipelago in eastern Indonesia.
A couple of them recently hatched, with two new sharks emerging, named Buddy and Marshal.
Both sharks are now being kept in a nursery on the island of Kri, hosted by the Raja Ampat Research and Conservation Centre (RARCC), a nonprofit of Papua Diving.
When Mongabay visited the hatchery at the end of January, the two juvenile sharks were kept in separate tanks. They were being fed daily, with food that is naturally available in their habitat, to the point where they would be strong enough to be released into the wild.
The shark rewilding project, called StAR (Stegostoma tigrinum Augmentation and Recovery) project, is an initiative that focuses on restoring zebra shark populations back to their natural habitat.
Only 20 zebra sharks are estimated to remain in Raja Ampat due to overfishing and habitat degradation.
Rewilding isn’t a novel idea — it has been implemented before with animals such as platypuses in Sydney and giant pandas in China. However, this marks the first attempt at rewilding sharks.
“This is the first-ever project in the world to translocate shark from aquariums and bring them to hatchery and release them to the wild,” Maryrose Tapilatu, an Indonesian shark aquarist who’s in charge of the RARCC hatchery, told Mongabay during the visit.
The target is to release 500 zebra sharks into the wild within 10 years of the project’s start in 2022, according to Nesha Ichida, a marine conservation scientist and a program manager for the StAR Project.
StAR Project is the first project to be implemented under ReShark, a global coalition of more than 90 conservation organizations, aquariums, government agencies and more, dedicated to recover threatened sharks and rays around the world.
The expectation is that enough shark pups will hatch in Raja Ampat to grow into a large, genetically diverse breeding population, Nesha said.
A robust breeding population of the sharks would in turn keep the balance of prey populations as they are essential regulators in the food chain. This in turn would balance the health of Raja Ampat’s coral reefs, crucial to support vibrant and varied underwater ecosystems.
And, if successful, it could set an example of how to reestablish populations of endangered species in other marine ecosystems that have been devastated by humans and to prevent them from going extinct.
“It’s a big pride for West Papua, Raja Ampat, and Indonesia in general, to have this project based in our country,” Nesha told ABC RN’s Saturday Extra.
Get to know zebra sharks
The zebra shark is a species of carpet shark found throughout the tropical Indo-Pacific, from Fiji and the Marshall Islands to Africa and the Red Sea.
It is best known for its characteristic stripes and spots. As a juvenile, it tends to have yellowish stripes, thought to mimic poisonous banded sea snakes (Laticauda colubrina). This zebra-striped pattern is an important defense mechanism for the small, vulnerable pups since it keep predators away. This is also where the species gets its name, zebra.
It is also known for its powerful tail that can be nearly as long as the rest of its body.
Laura Simmons, the regional curator for SEA LIFE Sydney Aquarium in Australia, called the zebra sharks “a striking, beautiful species.”
“It’s mainly that tail that always makes them seem so striking from a distance, because they are graceful little swimmers, and their tails are like big, long ribbons,” she told ABC RN’s Saturday Extra.
As a zebra shark matures, its stripes are replaced by small black dots, helping them blend in with the ocean floor. Due to the dots, it is sometimes called a leopard shark, especially in Australia and the U.K. It is, however, a different species than Triakis semifasciata, which is called a leopard shark in the U.S.
Zebra sharks are nocturnal, frequenting coral reefs and wriggling into their narrow crevices to hunt for mollusks, crustaceans and small bony fishes at night.
During the day, they are as sluggish as teenagers getting ready for school and are often found resting on the sea bottom. Unlike many other shark species, zebra sharks are usually docile and have a calm demeanor, making them easy to catch.
Zebra sharks were once widespread and abundant in Raja Ampat waters. But in the 1990s and early 2000s, they were severely overfished for their meat, fins and liver oil (used in making vitamins). Their fins are used for shark fin soup, a Chinese delicacy. A zebra shark’s dried fins are priced at around 2 million rupiah ($126) at the market.
These practices, coupled with the degradation of their habitat, have decimated zebra shark populations by up to 70% in the past decade, according to Maryrose.
As a result, they are listed as endangered by the International Union for the Conservation of Nature (IUCN), a global authority on the conservation status of species.
In certain areas like the Raja Ampat archipelago, they have nearly vanished, Maryrose said.
From 2001-21, Conservation International researchers carried out more than 15,000 hours of in-water surveys of the zebra shark in Raja Ampat, and they found only three individuals.
In its population viability analysis, the IUCN estimated about 20 individuals spread throughout the approximately 6 million hectares (14.8 million acres) of the Raja Ampat archipelago.
“We have a dive guide who has been diving here for 10 years. He has only seen three adult zebra sharks,” Maryrose said. “I personally haven’t seen one [in the wild]. This region is [part of] the Coral Triangle, the center of marine biodiversity. But how come we don’t see this shark?”
This makes the zebra shark functionally extinct in Raja Ampat, meaning that while it may have a few individuals still living in the region, its population has fallen below a critical point at which it can no longer produce the next generation.
The IUCN estimated that at least 200 sharks are needed to prevent extinction, and larger populations, around 2,000 individuals, are ideal to maintain evolutionary potential.
StAR
Without additional intervention like the StAR Project, it is unlikely for the zebra shark to recover and survive.
ReShark chose zebra sharks for its first project and Raja Ampat as the location because it saw an opportunity to recover declining populations of wild zebra sharks there.
Raja Ampat is located in the heart of the Coral Triangle, the most biodiverse marine area in the world, home to around 75% of the world’s all known coral species and known as the “Amazon of the seas.”
As a result, the archipelago has plenty of underwater terrain to support a robust zebra shark population.
This makes Raja Ampat an ideal location for the shark rewilding project.
Some initiatives have been made to recover the declining population of marine wildlife in Raja Ampat.
For one, the government has declared the entire waters of Raja Ampat as a shark and ray sanctuary, where the harvesting of both shark and ray is completely prohibited.
Furthermore, Raja Ampat also has a network of nine marine protected areas (MPAs), encompassing an area of more than 2 million hectares (4.9 million acres). Within those MPAs are some of the region’s largest and best enforced “no take” zones where no extractive activities are allowed, therefore leaving ecosystems mostly undisturbed.
The strict regulations are bolstered by regular marine patrolling and strong law enforcement, allowing marine wildlife to thrive.
“You can see the actual result of it. It’s one of the few places in the world that marine biodiversity is actually getting better,” Nesha of ReShark said. “Sites that are completely bombed back in the 2000s, it’s full of coral reefs now with every tropic level in the food chain. The majority of the reef sharks have rebounded.”
While these efforts have resulted in the return of some species like reef sharks and manta rays, zebra sharks aren’t recovering in the same way due to their slow population growth rate. The population is also not viable enough to sustain the next generation.
Therefore, conservationists had the idea of bringing zebra shark eggs from accredited aquariums around the world to Raja Ampat.
How does it work?
This idea was first proposed by Conservation International, when its Asia-Pacific team developed a concept plan for recovering zebra sharks in Indonesia.
Through genetic testing, adult sharks from the Eastern Indonesian-Oceania subpopulation have been identified at accredited facilities around the world. These broodstock are being purpose-bred for the StAR Project.
Egg cases produced by genetically appropriate broodstock at facilities accredited by the Association of Zoos and Aquariums (AZA) are then coordinated for shipment to Raja Ampat.
Since zebra sharks’ egg cases are hardy in nature, they’re able to tolerate trans-Pacific shipping.
So far, eggs have been shipped from the SEA LIFE Sydney Aquarium in Australia, the Shark Reef Aquarium in the U.S. and Cairns Marine, an organization in Australia that collects marine life, including shark eggs, from the wild and supplies them to zoos and aquariums.
In the latest batch of shipments in December 2023, the RARCC hatchery received 11 eggs from Cairns Marine, and the next batch of eggs is expected to come from the Georgia Aquarium in Atlanta, Maryrose said.
Australia has a relatively healthy number of zebra sharks thanks to established government protections, particularly in several MPAs such as the Great Barrier Reef Marine Park and Moreton Bay Marine Park in Queensland.
“These animals have been protected from fishing for many, many years, and that has helped keep their population stable and healthy,” Simmons said.
At SEA LIFE Sydney Aquarium, four sharks have been enlisted for the StAR Project. Two are males — Leo and Gohan, who has already fathered a number of females. The other two are females — Zimba and Kaya.
After mating, the females lay large (17 centimeters, or 6.7 inches, in length), brown, leathery eggs.
These eggs are then closely monitored for a certain number of days to verify that they’re actually fertilized and viable, Simmons said.
“Once we see a little embryo wiggling in them, time is of the essence,” Simmons said. “At week 10, it’s when we’d like to ship the eggs to Raja Ampat, and we have until week 15 to ship them because that’s the sweet spot for sending the eggs to Raja Ampat.”
The eggs are carefully packed in coolers and flown to Raja Ampat as quickly as possible, Maryrose said.
This is to ensure that the eggs can acclimatise to Indonesian water immediately, she said.
“They [the eggs] used to live in a water environment that’s different from here. So the first crucial thing we have to do is acclimatising them to the water here,” Maryrose said. “Once we’ve done that, we can put them in the egg tanks.”
The eggs take another month or so to hatch, emerging as 10-inch baby sharks, known as pups.
They’ll then go to pup tanks where they’re taken care of and fed by specially trained aquarists, or “shark nannies,” like Maryrose.
When they reach a length of about 50 cm (20 in), they’ll get tagged using RFID and acoustic tags. The acoustic tags are put on their fins so that when they go to the surface, the tags will send signal to the satellite.
The RFID tags, meanwhile, is a microchip that you usually put on dogs and cats. These tags will give signal to the transmitter that’s already submerged in areas designated for the zebra shark.
“There are 16 transmitters in Wayag [where the sharks will be released]. So every time they pass the transmitters, it will send a signal that our sharks are there,” Maryrose said.
After that, the sharks will be transferred to a sea pen, where they are introduced to other marine life.
If they displays normal behavior and good health, they’ll be released around designated areas within Raja Ampat.
The IUCN estimated that the designated areas could host between 1,000 and 2,000 sharks.
These areas are surrounded by deep water that zebra sharks are unlikely to cross. They also include the nine MPAs.
Once they’re released into the wild, the sharks are monitored regularly, with active monitoring done every two to three months, and movement pattern data retrieved and analysed every six months.
Challenges
While the rewilding project has brought much needed hope to the future of the zebra shark, sometimes reintroductions effort can also fail.
For one, shark eggs can die on arrival if they spend too much time in shipment and quarantine, Maryrose said.
This happened during the first batch of shipment in August 2022, in which the RARCC hatchery received six eggs from the SEA LIFE Sydney Aquarium.
Three of the eggs didn’t survive after embarking on an epic, multiday transit and traveling more than 4,200 km (2,600 mi) due to the lengthy and rigorous permitting and government approval process, Maryrose said.
“The government needed to sign permit because they’re bringing living animals from outside the country, so they needed to be quarantined, and there’s a lot of paperwork that needs to be done,” she said. “Some of them [the eggs] already lacked of oxygen, so they didn’t make it here.”
In another case, a juvenile zebra shark hatched from the project was released into the wild too soon, Maryrose said.
“In another batch, they already have the shark hatched, but the shark is not strong enough,” she said. “So when we put that shark in the wild, it died as soon as it reached the sea.”
The zebra shark is also still threatened by shark finning, as there’s still demand for its fins and meats, despite government restrictions on the killing of sharks and rays in Raja Ampat, Maryrose said.
“Even though us Indonesians don’t eat sharks, and none of us are interested [in eating them], but the profits from selling them to other countries are too big for fisherfolks to resist,” she said. “That’s why we need some innovation,” to improve the livelihoods of fisherfolks without killing sharks.
Despite the challenges, Maryrose is hopeful that juvenile sharks from the hatcheries like Buddy and Marshal can thrive and repopulate the waters of Raja Ampat, since the government has thrown support behind the project.
Furthermore, the region has been designated as a protected area, with rangers patrolling the region to provide a refuge for sharks, rays, turtles and other marine life.
When Mongabay visited the RARCC hatchery in January, Marshal was 4 months old.
She will soon be transferred to the sea pen and spend about a month there, before being released into the wild and joining four zebra sharks — named Mali, Audrey, Charlie and Kathlyn — that have been released to the turquoise waters of Raja Ampat. All four originated from SEA LIFE Sydney Aquarium’s breeding program.
“For me, it’s hard to release her [Marshal] to the wild, but I’m really hoping the best for her, so she can grow well, eats lots of food, and find her siblings out there,” Maryrose said.
For more information, visit www.reshark.org
CORRECTION (17/04/2024): The article has been revised to correct the misspelling of Marshal and change “hatchery” into “nursery”.
Banner image: A young zebra shark (Stegostoma tigrinum) swimming among the mangroves. Image courtesy of Indo-Pacific Films.
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