Background: The Ganges River dolphin (Platanista gangetica gangetica), an endangered freshwater cetacean, is recognized as a sentinel species for evaluating the ecological integrity of South Asian River systems. Its persistence reflects the condition of aquatic habitats, positioning it as a vital bioindicator for conservation planning. In Nepal, the Koshi River is one of six major river systems having particular importance as it supports the traditional Malaha community, whose livelihoods depend on fishing. The Malaha’s cultural identity, oral traditions, and social practices remain closely linked to riverine resources, with dolphins symbolizing prosperity, ecological balance, and harmony between nature and society.
Methods: Between June 2022 and April 2024, dolphin abundance, socio‑ecological linkages, and anthropogenic stressors were examined using systematic sighting surveys, stakeholder interviews, field observations, participatory threat mapping, and key informant interview.
Results: A localized population of 19–20 dolphins were recorded in 2024 near the Koshi Barrage, displaying cooperative foraging behavior that indirectly benefits local fishers. However, fish biomass has declined by nearly 75% over two decades due to overfishing, toxic catch practices, and cross-border barriers restricting migratory pathways. Additional pressures include agricultural runoff, domestic effluents, barrage operations, vehicular vibrations, and seasonal low flows that fragment habitats. Despite these threats, cultural reverence for dolphins and the Malaha community’s traditional ecological knowledge provides crucial opportunities for inclusive stewardship.
Conclusion: Inclusive stewardship combining scientific monitoring, traditional knowledge, and regional cooperation is essential to safeguard Koshi River dolphins, restore fish biomass, and sustain Malaha livelihoods while preserving cultural and ecological integrity.
Ganges river dolphin, Koshi River, community-based conservation, ethno-ecological knowledge, freshwater biodiversity, threats assessment
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