By Vishal Gulati, IANS,
Shimla : Thousands of fish have died in the past two days in Himachal Pradesh’s Rewalsar wetlands. Experts say they were either poisoned or did not have enough oxygen.
The Rewalsar wetlands, located about 125 km from here, have religious and ecological importance. It was included in the list of wetlands of national importance in 2005 by the Ministry of Environment and Forests.
Shoals of dead fish have been spotted floating on water or lying along the banks of the wetlands, B.D. Sharma, director fisheries department told IANS Wednesday.
He said the deaths may be due to high density of aquatic fauna or increase in concentration of some toxic chemical in the water.
The department has collected water samples and sent them for analysis.
“The exact cause of fish mortality can be known only after the analysis,” Sharma said.
Studies conducted by the Himachal State Council for Science Technology and Environment said the Rewalsar wetlands are under strain due to pollution, siltation, encroachment and overgrowth of weeds.
Over the years, the average depth of the wetlands has reduced from 10 to six metres. Weeds cover over one-sixth of the water body.
M.S. Johal of the department of zoology, Panjab University, Chandigarh, believes that the death of fish may be due to the overgrowth of algae that depletes dissolved oxygen in shallow water.
He said religious tradition like feeding the fish is a significant contributor to overgrowth of algae.
“Since most starchy items are not eaten by the fish, this results in pollution and growth of micro-organisms in the water body. Pollution depletes dissolved oxygen in water, suffocating the organisms,” says Johal, who was the chief investigator of an Indo-US project on the ecology of hill streams of Himachal Pradesh.
He said the government should impose a ban on offering food to the aquatic creatures.
Regular monitoring of the quality of water must be carried out to check further fish mortality, he said.
R.K. Sood, joint member secretary of the Himachal State Council for Science Technology and Environment said rapid urbanisation and development activities, especially by the managements of places of worship, have put a tremendous pressure on the water body.
He said the water is also turning more toxic due to nutrients and pesticides that run off from agricultural fields during the rainy season.
He said there is a central government-funded plan to treat the catchment of the wetlands by increasing the green cover and constructing silt-detention dams.
Septic tanks, constructed around the water body, are also putting tremendous pressure on the wetlands. Most of the tanks don’t adhere to standards, resulting in the seepage of pollutants into the wetlands. For this, the council has asked the Rewalsar notified area committee to replace leaky tanks.
The state fisheries department director said that since the water body is “overcrowded” with aquatic creatures, the department has started their selective harvesting.
Earlier, the harvesting was not carried out due to religious sentiments of the devotees.