VICTORIA, Seychelles — Marine researchers from the Marine Conservation Society Seychelles and the Madagascar Whale Shark Project have confirmed that a whale shark nicknamed Mistral made a journey of approximately 1,200 kilometres from Nosy Be in Madagascar to the waters off Mahé, marking the first confirmed cross-border whale shark movement between the two countries and reshaping regional understanding of how these iconic marine animals use the western Indian Ocean. The discovery was made on December 3, 2025, when researchers compared photographs and confirmed through pattern recognition software that the same individual had been sighted in both Madagascar and Seychelles, and has since been published in Oryx, The International Journal of Conservation.
The discovery carries significant implications for how Seychelles and its regional partners manage and protect whale shark populations, as it demonstrates that these animals are not confined within any single national exclusive economic zone but move freely across vast ocean corridors, making their conservation a shared regional responsibility rather than a purely domestic concern. For Seychellois, the finding is also a reminder of the exceptional marine heritage that lies in the waters surrounding the archipelago and the importance of sustained scientific investment in understanding and protecting it.
Mistral was first photographed in Nosy Be six years before the Seychelles sighting, providing researchers with a six-year photographic record of the same individual animal. The Marine Conservation Society Seychelles has been running a research and ecotourism programme using a dedicated vessel to locate whale sharks, collect identification photographs, and allow visitors to observe them under strict guidelines since 2015, and has identified 546 individual sharks through this work, every one of them a juvenile male. However, sightings at the Seychelles site have declined sharply since the Covid-19 pandemic, falling from 140 in 2019 to just 38 in 2025, a trend that researchers say underscores the urgency of understanding whale shark ecology and movement patterns.
Both MCSS and MWSP use Interactive Individual Identification System software that compares new images to all sharks already catalogued in the database, enabling researchers to track local movements, assess site fidelity, and estimate population size. Of the 33 individuals identified during the Seychelles season examined in the study, seven were encountered more than once, providing valuable information on short-term movements and site use, while researchers also identified a strong male bias among the sharks sighted, with 21 males, one female, and 11 of unknown sex recorded during the period.
Mistral’s journey builds on previous evidence indicating that whale sharks in the western Indian Ocean are not confined to national waters but move across vast regional corridors, and the finding underscores the importance of long-term monitoring, citizen science, and cross-border collaboration in generating the data needed to protect these animals. Researchers stress that as climate change and human pressures continue to reshape the ocean, such insights are essential for ensuring the survival of one of the world’s most iconic marine species across the western Indian Ocean.
The confirmation of Mistral’s 1,200-kilometre journey is a milestone for regional marine science and a compelling argument for coordinated conservation strategies that recognise whale sharks as shared natural heritage across the Indian Ocean island states.
