CHENNAI: Thousands of fish, mostly juveniles, have choked to death in the past one month at Kovalam estuary, about 30 km south of Chennai, due to an increase in pollution load. Incessant pre-monsoon rains have drained pollutants from upstream into the estuary, and with the bar mouth blocked by sandbar, a toxic cesspool has been created with no escape for the fish, just a stone’s throw from the recently Blue Flag certified beach.
TNIE visited the estuary on Saturday morning and saw dead fish along the banks of the waterbody. The water stank, indicating mixing of untreated sewage and industrial effluent. As per a rough estimate by the Central Marine Fisheries Research Institute, that runs an experimental station at Kovalam, `10 crore worth fish, green mussels, and crab stocks, have perished in three months.
Hanif Mohammed, owner of Freshfins and professional angler, said: “It is a great loss for fishermen. I use the backwaters for kayaking and other water sports besides fishing. In the last one week alone, I have cleaned and disposed of more than one tonne of fish.”
The famed Kovalam Blue Flag beach lies adjacent to the bar mouth. After complaints of fish kills, the Public Works Department recently cut open a small portion of sandbar allowing tidal flow between the estuary and sea. The beach is thronged by hundreds who go for a swim. With the highly-polluted estuary waters flushing into the sea, the quality of water in the beach may not be fit for bathing. This is also a surfing area. Sources said Chief Minister MK Stalin is likely to visit the beach on October 16.
Kovalam crisis is worrying, say researchers
Joe K Kizhakudan, officer-incharge at the Kovalam Field Laboratory of CMFR I, told TNIE the root cause of the crisis was the choking of Kovalam bar mouth. For the last three months, it has been closed due to formation of sandbar. “For survival of any estuary, there should be constant exchange of sea water.
When this stops, eutrophication happens. What is happening at Kovalam is really worrisome. Due to anthropogenic activities, a high level of nutrients is carried into the estuary, resulting in (algal) bloom,” Kizhakudan said.
In 2015, a team of five researchers published an article in an international science journal, Science Inventions Today, on how the Kovalam estuary has been continuously reporting bloom of toxic algae. Supriya Sahu, chairman of the TNPCB, said authorities will be instructed to collect water samples and initiate corrective measures.