TN Government to adopt biological control method to curb Kakka Aazhi

CHENNAI: Even as the Water Resources Department (WRD) has already commenced dredging of Kosasthalaiyar River to remove invasive Kakka Aazhi (Mytella strigata), the state chief secretary N Muruganandam has directed the Tamil Nadu State Wetland Authority (TNSWA) to implement biological control measures as a pilot study.

During a meeting held to discuss the invasion of Kakka Aazhi, a few days ago, it was apprised that the National Institute of Ocean Technology (NIOT) has given a proposal for chemical control of the invasive mussel, which may affect the aquatic ecosystem in the river.

Following this, Central Marine Fisheries Research Institute (CMFRI) has been asked to submit a proposal for biological control. However, CMFRI explained that the biological control method would yield successful results only in the dredged area since the multiplication rate of Mytella strigata is very high and any attempt to biologically control the species without dredging will be a wasteful exercise.

Based on the discussions, Muruganandam directed WRD to start dredging in Kattupalli, Puzhuthivakkam and Athipattu areas (1.7km of the river) as per the directions of National Green Tribunal (Southern Zone) and do a quick baseline study to measure the impact along with TNSWA. Moreover, directions were issued to carry out biological control measures in dredged areas.

Meanwhile, Deepak Srivastava, member secretary of TNSWA, informed the NGT that the biological control of Mytella strigata shall be a long-term solution to control the spread, which has never been attempted in Tamil Nadu. "Keeping in view the rapid multiplication of the Mytella strigata the biological control method shall be implemented on pilot basis in the selectively dredged area and the effectiveness of biological control of the Mytella strigata shall also be validated during this pilot study," the report the Tribunal said.

A joint inspection was conducted by the officials of Tamil Nadu Wetlands Mission, WRD, National Centre for Sustainable Coastal Development (NCSCM), Dr MGR Fisheries College and Dr J Jayalalithaa Fisheries University along with local fishermen on November 21 in a 1.7Km stretch which is proposed to be dredged. The Water Resources Department has informed the team that formation of pit work is in progress and one dredger has been deployed in the Kosasthalaiyar backwater, and the dredging work will be commenced in full-fledged manner.

In October, the NGT directed the government to engage more men and machines to remove the invasive species. It may be noted that the government is blaming Ennore Port, Chennai Port and Kattupalli Port for the invasion claiming that ballast water as the possible source.