Madagascar · Global Whale Shark Program · Since 2016

Madagascar Whale Shark Project

Young whale sharks aggregate off Nosy Be from about September to December, and the Madagascar Whale Shark Project has studied and protected them since 2016.

Led by Madagascar Whale Shark Project, with MMF

546whale sharks identified off Nosy Be

4,000 km+round trip made by one satellite-tagged shark

20acoustic receiver stations around Nosy Be in 2025

300+tourism professionals trained in the code of conduct

The Madagascar Whale Shark Project is a collaborative project focusing on whale sharks (Rhincodon typus) and other megafauna species in northwestern Madagascar, centered on the island of Nosy Be. It is led by its founder, MMF research associate Stella Diamant, and MMF works with the project on its whale shark research.

The project began in 2016, working with citizen scientists within the marine tourism industry, and has since expanded into an integrated research, education, and conservation project spanning multiple species in this global biodiversity hotspot. Its whale shark work covers population ecology, tagging and tracking, and ecotourism, all aimed at understanding and protecting the whale sharks of Nosy Be. MMF’s Dr. Simon Pierce and Dr. Chris Rohner collaborate with Stella and the project team on this research, and MMF also works with the project on the manta and devil rays of Nosy Be.

A whale shark silhouetted against the sunlit surface, with snorkelers above and below it

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Whale sharks of Nosy Be

Founded in Nosy Be

Stella Diamant, a biologist with an MSc from Imperial College London, established the Madagascar Whale Shark Project in 2016 following her own encounter with a whale shark in Nosy Be. As project lead, she focuses on collecting ecological data, advocating for sustainable management, and promoting education within local communities and among the wider public. (Photo: Madagascar Whale Shark Project.)

The project’s key successes to date:

Identified 546 whale sharks off Nosy Be by the end of the 2025 season, contributing to our understanding of their population.
Supported the recognition of Nosy Be’s waters as a Key Biodiversity Area, and helped make the case for the Tandavandriva marine corridor, which links two existing protected areas and received temporary protection in March 2026.
Enshrined the whale shark tourism code of conduct in Malagasy law, making it the legal standard for operators in the local ecotourism industry.
Showed that Nosy Be’s whale shark tourism industry was worth an estimated US$1.5 million over the three-month 2019 season, strengthening the economic case for protecting the sharks.
Established Nosy Be as an IUCN Important Shark and Ray Area.

Stella Diamant and captain Christian on the project's boat

Population structure and residency

Photo-identification had recorded 546 whale sharks off Nosy Be by the end of the 2025 season, with some individuals returning for about a decade; two sharks, Hugo and Alphonse, have been seen in every survey season since 2015. The project’s 2021 study of the 408 sharks identified from 2015 to 2019 found that all were immature, ranging from 3 to 8 m (10 to 26 ft) in length, and that 82% of those sexed were male; it also found that much of the sharks’ preferred habitat lay outside existing protected areas. The sharks arrive from about September to December to feed, usually at the surface alongside feeding tuna and seabirds. Most are feeding on small baitfish; in some seasons, however, the team has instead found them feeding on dense surface swarms of krill, a reminder that what draws whale sharks to a place can shift from year to year.

A young whale shark swims below a freediver in clear blue water

Tagging and tracking

Satellite tracking has shown that some sharks undertake substantial movements away from Nosy Be: one traveled to southern Madagascar before returning, a round trip of more than 4,000 km (2,500 miles). The tracks also revealed a secondary hotspot off Pointe d’Analalava, about 180 km (110 miles) southeast of Nosy Be.

That work also identified a high-use area around Nosy Be itself, which is now covered by a network of underwater acoustic receivers (twenty stations as of the 2025 season) that detect tagged sharks around the clock. The receivers have shown that whale sharks use Nosy Be year-round, often at night or offshore where they would not be seen from a boat. These results supported the recognition of the Key Biodiversity Area and are contributing to the establishment of the Tandavandriva marine corridor.

A whale shark towing a tag on a tether, with a snorkeler above it

A code of conduct, now in law

A code of conduct has been developed and implemented within the whale shark tourism industry since 2017, and in December 2023 it was formalized in Malagasy law by inter-ministerial decree, applying to operators working with whale sharks, marine mammals, and sea turtles alike. More than 300 tourism professionals have been trained, including through a three-module course delivered in 2024 that certified 68 operators.

Enforcement remains a challenge, however: boats still work with whale sharks without following the code, putting both the animals and the swimmers in the water with them at risk. (Photo: Madagascar Whale Shark Project.)

A whale shark code of conduct sheet held up on a boat

Ocean Ambassadors in Nosy Be

For the 2026 season, nine new Ocean Ambassadors from Nosy Be communities and partner projects are joining the Madagascar Whale Shark Project’s program. After two weeks of training in marine biodiversity, environmental education, regulations, and field responsibilities, they combine outreach on land and at sea with data collection on the impacts of tourism. Brian, who carried out master’s research with the project during the previous season, has joined the team full-time to coordinate this work.

Connecting the western Indian Ocean

In 2019, a juvenile male whale shark was photographed off Nosy Be and added to the catalog as Mistral. In August 2025, he was photographed again off Mahé, in the Seychelles, more than 1,200 km (750 miles) away and now around 6 m (20 ft) long. Matched from his spot pattern through a collaboration between the Madagascar Whale Shark Project and the Marine Conservation Society Seychelles, the record is the first confirmed movement of a whale shark between the two countries, and it was published in the journal Oryx.

With support from MMF, Stella visited the Marine Conservation Society Seychelles in 2026 to share data-collection protocols, train volunteers, and contribute to whale shark monitoring in the Seychelles.

Single records like this carry more weight than their number suggests, because whale sharks that move between countries benefit most from protection planned across national boundaries. Nosy Be is recognized as an IUCN Important Shark and Ray Area, alongside oceanic manta rays and devil rays that use the same waters. The next step for this work is to build that recognition into connected protection across the western Indian Ocean.