Rediscovery of the Ganges Shark in Indonesia’s Sesayap River

In 2023, a team led by marine biologist Michael Grant of James Cook University documented 17 Ganges sharks caught by a single fisherman in the Sesayap River, North Kalimantan. The catch exceeded the total number recorded worldwide in the previous two decades. Follow-up sampling in 2026 added further specimens, bringing the combined count to 43, most identified from dried fins found in local villages. The International Union for Conservation of Nature (IUCN) Red List estimates only about 240 adult Ganges sharks remain across their historic range, making this concentration potentially the last viable population.

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The Ganges shark (Glyphis gangeticus) is one of three river-shark species globally and has not been photographed alive. Its known range includes Pakistan, India, Bangladesh, Malaysia and Myanmar, with the last confirmed sighting near the Ganges River in 2017. Researchers noted that the species is not valued for its meat or fins, reducing direct market pressure. However, bycatch remains a risk, especially as fisheries shift toward gear that may increase accidental captures. Sarah Fowler, scientific adviser at the Save Our Seas Foundation, warned that the expanding multibillion-dollar fish-maw industry—targeting dried swim bladders—poses an “firing line” for the shark.

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The IUCN Shark Specialist Group designated the Sesayap River an Important Shark and Ray Area (ISRA) in 2024. Fahmi of Indonesia’s National Research and Innovation Agency cautioned that comprehensive data on population trends and community use are still lacking. He suggested area-based protections that could also safeguard co-occurring Irrawaddy dolphins and giant freshwater rays. Community surveys in 2023 found only one of 221 fishers aware of existing ray protections, underscoring the need for education and incentives such as improved health and schooling services.

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• “It was such an exciting and important discovery,” — Benaya Simeon, an Indonesian doctoral candidate at Charles Darwin University.

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• “The Ganges shark … is definitely in the firing line,” — Sarah Fowler, scientific adviser at the Save Our Seas Foundation.

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• “We still have very limited data about this species, but at the same time we are racing against extinction,” — Benaya Simeon, an Indonesian doctoral candidate at Charles Darwin University.

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