Evidence of Opportunistic Macro-Predatory Attempts by the Endangered Ganga River Dolphin (Platanista gangetica) on Mega-Prey Biomass

Background: The endangered Ganga River dolphin (Platanista gangetica) is generally characterised as a predator of relatively small fish, whereas evidence of attempted interactions with substantially larger prey remains limited. Aim: This study examined preliminary observations of possible capture attempts involving relatively large fish near the Ganga–Ghaghara confluence in Bihar, India. Methods: Field assessments of fish obtained through routine artisanal fishing activities were combined with structured interviews and focus group discussions involving 50 fishers. Fish specimens were examined opportunistically, and fisher-reported observations were used to describe dolphin–fishery interactions. Results: A Wallago attu specimen measuring 105 cm and weighing approximately 8.0–9.0 kg exhibited a healed, concave caudal injury. The injury was considered consistent with a possible dolphin interaction, although its cause was not directly observed. A separate eyewitness account described an encounter involving a 30–35 cm Catla catla. Among respondents, 98% reported dolphins targeting fish near fishing nets, 90% identified river confluences as frequent dolphin-sighting locations, and 96% reported dolphins following fishing boats. Additionally, 92% reported no accidental dolphin entanglement in their nets. Conclusion: The combined observations suggest that attempted prey capture may occasionally involve fish larger than those commonly documented in dietary studies. However, they do not establish the cause of the healed injury, successful ingestion of large prey, or the frequency of such events. Further direct behavioural observations and systematic injury assessments are required.