Founder’s Briefs: An occasional series where Mongabay founder Rhett Ayers Butler shares analysis, perspectives and story summaries.
In the turquoise shallows of Raja Ampat, Indonesia, a conservation experiment is attempting the rewilding of an endangered shark.
The initiative, known as ReShark, seeks to restore populations of the Indo-Pacific leopard shark (Stegostoma tigrinum), also called the zebra shark, to reefs from where it had vanished. Led by Re:wild in partnership with the IUCN SSC Shark Specialist Group (SSG), Conservation International, the Association of Zoos and Aquariums, and more than 100 institutions in 20 countries, the project draws comparisons to terrestrial reintroductions such as that of wolves in Yellowstone in the U.S.
“This is a first for the ocean, and especially for sharks,” Mark Erdmann, ReShark’s executive director, told me. The effort involves breeding sharks in captivity, shipping their eggs across oceans, hatching them in Indonesian nurseries, and releasing them into the wild. In less than three years from its first planning meeting, the team achieved its first release.
Leopard sharks once thrived in Indo-Pacific shallows but were decimated by the shark fin trade. By the time Raja Ampat became a shark sanctuary in 2012, the species had already disappeared locally. Genetic research revealed that populations in Australia’s Great Barrier Reef share the same eastern Indo-Pacific lineage, making reintroduction feasible.
The breakthrough came when aquariums — so successful at breeding leopard sharks they sometimes separate sexes to prevent overpopulation — offered surplus eggs. Transport protocols now allow eggs to be shipped from the U.S. to custom hatcheries in Raja Ampat within 40 hours. There, “shark nannies” raise the pups on wild shellfish before moving them to sea pens for a growth phase.
So far, 126 eggs have been shipped, 82 pups hatched, and 39 released. Modeling suggests 50 to 75 releases per year could reestablish a viable population within a decade — far faster than natural recovery.
Local communities are central to the project. Indonesians have been trained to manage hatcheries, children help feed pups, and former shark fishers have joined releases. “We’re cultivating the next generation of shark lovers,” Erdmann said.
The program has also reshaped perceptions of aquariums, positioning them as partners in active species recovery. New efforts are underway in Thailand, and more species are in the pipeline. Erdmann remains cautious: without strong marine protections, rewilding could fail. Yet in an era of accelerating biodiversity loss, ReShark offers measured optimism, backed by science.
Read the full story by Rhett A. Butler here.
Banner image: An adult leopard shark at the North Stradbroke Island summer aggregation site in Australia. Image courtesy of M.V. Erdmann.
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