Amingaon, Oct 17: The sighting of dead fish floating in Deepor Beel Wildlife Sanctuary has raised concerns, but experts have ruled out any unnatural cause behind the deaths in the State’s lone Ramsar site.
Speaking to this correspondent, globally acclaimed environmentalist Laxman Teron said, “It is not a matter to be reckoned with, as the death of fish in Deepor Beel during the months of Aahin and Kati (September and October, extending up to November 15) has been part of a natural process for a long time.”
Explaining the phenomenon, Teron said certain fish species feed on the ripe seeds of a submerged aquatic plant found abundantly in the wetland. “The seeds, which are very lubricious, ripen during this period, and some fish gorge on them. After feeding, the stomachs of the fish swell, which can lead to their death,” he said, adding that the seeds are also a delicacy for migratory birds.
“The seeds of this aquatic vegetation are alkaline in nature and can be fatal to fish if consumed in large quantities,” Teron explained. He, however, said he could not say whether the same phenomenon occurred in other wetlands.
Meanwhile, an official of the Pollution Control Board of Assam (PCBA) said the board had not received any complaint regarding the matter. An official of the Fisheries Department also said the department was yet to receive any information about the incident.
Dr Migrendra Mohan Goswami, former Head of the Department of Zoology at Gauhati University, said the decomposition of certain aquatic plants begins after summer, prompting some fish species, including rou, bhakua, sol and sal, to feed extensively on the decaying vegetation.
Fish mortality has often been reported in such circumstances, he said. “Post-monsoon, submerged aquatic vegetation like Naias indica, and Hydrilla verticilata start decomposing, leading to the formation of debris. Detritivorous fish that consume excessive quantities of this material sometimes die,” Goswami said.
A local resident, however said that it was too early to draw any conclusion about the cause of the fish deaths and called for an investigation by the concerned department.
The latest incident comes amid recurring concerns over pollution at Deepor Beel, where earlier reports highlighted the impact of waste from Guwahati entering the wetland through the Pamohi River and raised questions about deteriorating water quality.
Environmental concerns have also centred on the Boragaon dumping ground, with pollution posing a threat to aquatic life and the livelihoods of local fishing communities.