Why in news?
Researchers from the University of Kerala and international partners have launched a long-term study to investigate the unique cooperation between local fishers and Indo-Pacific humpback dolphins in Kerala's Ashtamudi Lake. The project aims to document how dolphins drive fish toward the fishers' nets and how this inter-species behaviour benefits both parties.
Background
Ashtamudi Lake is a large estuarine system on the Kerala coast and a designated Ramsar site. It is known for its rich biodiversity, traditional clam fishing and scenic backwaters. For generations, local artisanal fishers have observed that Indo-Pacific humpback dolphins (Sousa chinensis) herd schools of mullet toward shallow waters where fishers cast their nets. This phenomenon has been documented in scientific studies of "dolphin-assisted cast net fishery".
Understanding the dolphin-fisher interaction
- How the cooperation works: Observations suggest that dolphins rush toward prey with rapid, zig-zag movements and even toss fish into the air. Fishers recognise this behaviour and quickly cast their nets ahead of the dolphins. The presence of dolphins often increases the catch size compared with fishing without them.
- Research methods: The new study will use acoustic monitoring, drone surveys and photo-identification to track dolphin movements. Interviews with fishers will document traditional knowledge and gauge whether dolphins respond to specific human cues or act independently.
- Conservation angle: Indo-Pacific humpback dolphins are listed as "Near Threatened" on the IUCN Red List. Heavy boat traffic and habitat degradation in Ashtamudi Lake pose risks to the resident population. Scientists hope that understanding cooperative behaviour will inform conservation and sustainable fishing practices.
Significance
The study promises to shed light on a rare example of human-wildlife cooperation. By documenting the mechanisms behind this interaction, researchers aim to improve the livelihoods of local fishers while protecting an iconic dolphin species. The findings may also inform similar fisheries elsewhere, emphasising the value of traditional ecological knowledge.
Sources: IndiaVision ยท Indian Journal of Fisheries