Mass fish kill raises pollution concerns at Hesaraghatta lake

Bengaluru: A significant fish kill event has occurred in the eastern region of Hesaraghatta lake, leading the Karnataka State Pollution Control Board (KSPCB) to investigate the source of the problem.

The KSPCB is specifically testing rainwater runoff from areas bordering the lake on the east side, separated by Mathkur Road.

The heavy rainfall over the past two days resulted in a large number of small fish being scattered across the exposed land around the lake.

These fish, some clumped together in groups of several hundred, were visible on dry undergrowth and even on leaves carried by the storm water. The situation was further exacerbated by a strong stench emanating from the lake's edge, particularly near the bamboo forest behind the Animal Husbandry Department's Semen Collection Centre.

Birder V Selvarajan of Green Circle, who spotted the bunches of fish on Sunday, led officials of the Karnataka State Pollution Control Board (KSPCB) to the spot. Some of the fish were half decomposed and remained untouched by birds hovering the area.

Soon, a 200-metre trail of dead fish led to a nala beyond the fence that separated the lake from the road opposite the Semen Collection Centre.

The dead fish, scattered around the drain formed by storm water erosion, had no water. The fish, appeared to belong to the Puntius family, measures about five to seven centimetres.

“All the dead fish belong to the same family. If this is due to any contamination, it is a matter of concern because Hesaraghatta is home to several bird species. The cause of the fish kill should be investigated at the earliest and measures should be in place to prevent any recurrence,” Selvarajan said.

KSPCB member secretary HC Balachandra said he has sought a detailed report from the Environment Officer (EO) concerned.

Water samples collected

On Monday, Dasarahalli EO Suresh and his deputy Pavan collected water samples from the area.

"We have several organisations in the nearby area, starting with the Fish Seed Production to the State Semen Collection Centre, poultry and pig breeding farms. The test of runoff water should tell us if the fish were already dead before being washed into the lake area. Samples of fish will also be sent to the lab,” Suresh told DH.

Officials said a scientist they consulted also hinted at possible Tilapia lake virus disease, a pathogen which attacks fish grown in farms. “The toxicology report should reveal the cause of death,” he added.