CHENNAI: More than a tonne of tilapia was found dead in a channel near Korattur Lake on Wednesday, less than a month after an estimated four to six tonnes of fish washed up dead in the Kosasthalaiyar River near Ennore. Fisheries Department officials suspect the Korattur fish died after being trapped in stagnant water with low dissolved oxygen levels.
According to an official, the sluice gate of Korattur Lake was opened on September 7 as part of monsoon preparedness, allowing water and several fish to move into a channel which eventually leads to Retteri Lake.
The gate was closed soon afterwards because of ongoing metro waterworks nearby. With the flow cut off, the fish remained trapped in the channel for a prolonged period, and officials suspect oxygen levels in the stagnant water fell. “If the sluice had remained open, the water would have continued to flow, and the fish could have reached Retteri Lake,” the official said.
The fisheries department removed around 300-400 kg of dead fish, while civic workers cleared the rest.
Even as officials dealt with the Korattur fish kill, more than 100 residents from eight fishing villages in Ennore gathered outside the fisheries department office on Wednesday, demanding the state release lab reports on the August 16 mass fish deaths in the Kosasthalaiyar.
Fisherfolk suspect toxic discharge from industries and thermal power plants in the river area and say the episode has badly affected both catches and consumer confidence.
R L Srinivasan (46), a fisherman from Kattukuppam, said fish availability in the river had completely fallen since the incident, and even if they managed to catch a few by riding boats farther into the river, buyers were reluctant to purchase the catch.
Another resident, Vishanth S, questioned why the TNPCB and fisheries department had not made their findings public nearly 25 days after collecting fish and water samples.
Environment and Climate Change Minister V K Rajeev told the Assembly last month that sewage from surrounding areas, rather than industrial effluents, polluted the water preceding the Ennore fish kill. Residents, however, are not convinced by that explanation.
A fisheries department official said a four-member committee comprising officials from the department and TNPCB, along with a professor from the fisheries university, was examining the laboratory’s findings. The committee is expected to submit its report within a week, the official said.