KOLLAM: A parasitic marine leech previously found only along the Atlantic and Mediterranean coasts has been reported for the first time in Indian waters -- off the Kollam coast. The finding has raised concern among researchers about the parasite's potential impact on fish health, fisheries productivity and the marine ecosystem.
The species, Pontobdella muricata, was found among the trawl bycatch that landed at Sakthikulangara harbour. The specimen was found attached to the ventral side of a ray fish, confirming a new parasite-host association for a leech previously restricted to colder European waters.
Researchers say the leech poses no direct threat to humans but warn that it could severely affect native fish populations. Even a single leech can cause lesions, draw blood and create wounds that allow secondary infections -- reducing fish health and market value, says the study. The finding has triggered concerns about what else may be silently shifting to Kerala's waters.
The current detection is limited to deepwater skates, but researchers warn that the shift in parasite distribution may indicate changing ocean conditions, altered migration routes or broader ecological imbalances.
"Our marine ecosystem is already under extreme stress due to global warming, pollution, deep-sea fishing and declining fish stocks. With fisheries under unprecedented pressure, the emergence of a new parasite is a red flag," said Sarlin Pathissery, head of the zoology department, Fatima Mata National College, Kollam, who led the study.
"The new parasite could harm fish populations in the long run, especially in waters already stressed by overfishing, warming seas and species degradation. But how exactly this will affect the fishing community and the wider environment requires in-depth study," she said. "If such parasites spread to commercially important species, small fishers who depend on healthy, clean catch for their livelihood will be the most affected," the study notes.