Researchers from Karnatak University, Dharwad, have discovered that human activities, chiefly fishing interactions and vessel traffic, are the primary drivers of marine mammal deaths along the coast of Karnataka. Between July 2023 and September 2025, the team recorded 65 strandings of whales, dolphins, and porpoises across 39 beaches bordering the Arabian Sea. By conducting weekly transect surveys and setting up a rapid-response network with local communities and forest officials, the researchers established a critical baseline for understanding why these protected ocean creatures are washing ashore lifeless.
To gather this vital data, the team patrolled the 343-kilometre coastline primarily on foot and via coastal roads, collaborating closely with local fishing communities, non-governmental organisations, and citizen scientists who provided real-time reports of stranded animals. When an animal was found, veterinarians authorised by the local forest department performed post-mortem examinations directly on the beach to determine the probable cause of death.
The researchers then used geographic mapping software to conduct kernel density analysis, a method that pinpoints mortality hotspots by calculating where strandings are most highly concentrated. They discovered a dense cluster of incidents in the southern districts of Udupi and Dakshina Kannada. These animals, ranging from the frequently stranded Indian Ocean humpback dolphin to the elusive, deep-water Cuvier’s beaked whale, naturally regulate marine food webs and maintain overall ecosystem balance. However, the nutrient-rich shallow waters they rely on for feeding overlap heavily with intense human commercial activities.
The findings paint a stark picture of this coastal overlap, particularly during the pre-monsoon and monsoon seasons when fishing pressure and changing oceanographic conditions peak. Of the identifiable causes of death, the vast majority were directly linked to human pressures. Animals were found with crushing injuries from boat propellers, blunt force trauma from vessel strikes, and lungs filled with water due to drowning after becoming accidentally entangled in active fishing nets. Furthermore, digestive tracts were found severely blocked by ingested plastic debris and abandoned ghost nets.
The Indian Ocean humpback dolphin, a species that strongly prefers shallow nearshore waters, was the most frequently recorded species, accounting for over 60% of all strandings. While historical records merely noted the occasional presence of stranded whales and dolphins in India over the past two centuries, this new study establishes a systematic, long-term monitoring framework. By generating precise spatial mapping of danger zones and linking them directly to seasonal fishing practices, scientists now have actionable, geographic data rather than scattered anecdotal evidence.
Nevertheless, the researchers noted that almost half of the strandings had to be classified as having an unknown cause of death because the carcasses were in highly advanced stages of decomposition by the time they washed ashore, which limited detailed forensic pathology. Furthermore, the true death toll is likely much higher than reported, as many animals may have died at sea and disintegrated, or washed up on inaccessible, uninhabited stretches of coastline where they remained undocumented.
The research serves as an urgent call to action for sustainable coastal management. By exposing the direct human causes behind marine mammal mortality, the study provides policymakers and the fishing industry with the concrete evidence needed to implement targeted conservation interventions. These include developing safer, bycatch-reducing fishing gear, regulating vessel traffic in critical habitats, and actively removing discarded fishing nets from the ocean. Protecting these vital keystone species not only preserves incredible global biodiversity but also ensures the long-term health and resilience of the marine ecosystems upon which countless human coastal communities rely for their own economic survival.
