Researchers Discover Potential Last Viable Population of Ganges Sharks in Indonesia

Researchers have discovered a potential last viable population of the critically endangered Ganges shark in a remote area of North Kalimantan, Indonesia. Led by Michael Grant of James Cook University, an exploratory mission in 2023 revealed that a fisherman on the Sesayap River had accidentally caught 17 sharks in a single week. This figure exceeds the number of sharks identified worldwide over the previous 20 years. Subsequent fieldwork in 2026 brought the total number of identified specimens to 43, although much of the evidence consisted of fins drying in villages.

The Ganges shark is one of only three river shark species globally and is known for being extremely elusive. It has never been photographed alive, and biologists typically rely on dead specimens found as bycatch. According to the IUCN Red List of Threatened Species, only about 240 adults remain. While the species is found in parts of India, Pakistan, Bangladesh, Malaysia, and Myanmar, the last published sighting near the Ganges River occurred in 2017.

In response to the discovery, the IUCN SSC Shark Specialist Group designated the Sesayap River as an Important Shark and Ray Area in 2024. Benaya Simeon, a doctoral candidate from Charles Darwin University, noted that the existence of such a habitat in Indonesia was surprising given the pressures from mining, palm oil plantations, and human population growth. Grant stated that the population is unlikely to be targeted for poaching because the sharks have no cultural significance, the villagers do not like the taste of the meat, and the thin fins are not attractive to the Asian shark fin market.

Despite the lack of deliberate hunting, the species remains threatened by accidental bycatch. The sharks have been caught using hook and line methods intended for snapper and croaker, as well as gillnets. Researchers returned to the region in May to begin protection efforts for the population.