Engineers work on Polavaram dam on Godavari for smooth passage of Pulasa fish
Due to its taste and availability only for a limited period in the Godavari river, Pulasa fish is in high demand not only in coastal Andhra, but also across the state and it fetches around ₹4,000 per kg for fishermen during the peak season.
Engineers working on the Polavaram major irrigation project, being constructed on Godavari River in Andhra Pradesh’s West Godavari district, are making a special arrangement in the massive spillway of the dam for the smooth passage of a peculiar variety of fish found in the river.
Popularly known as “Pulasa Chepa” (Hilsa fish, scientific name: Tenualosa ilisha), it is actually a marine fish variety, but enters the Godavari river during the months of July and August for breeding. From Antarvedi in East Godavari district, where the river joins Bay of Bengal, the fish swims upstream of the river for more than 200 miles for breeding and returns to the sea by October-November.
Due to its taste and availability only for a limited period in the Godavari river, Pulasa fish is in high demand not only in coastal Andhra, but also across the state and it fetches around ₹4,000 per kg for fishermen during the peak season.
However, the construction of the Polavaram dam across the river has posed a big threat to the Pulasa fish, as its movement to the upstream of the river would be curtailed. “This was one of the issues raised by the Union ministry of environment and forests before considering granting environmental clearance for the Polavaram project. It asked the state water resources department to work out a mechanism for the passage of Pulasa fish,” Polavaram project chief engineer B Sudhakar Babu said.
Subsequently, the state government consulted the Central Inland Fisheries Research Institute (CIFRI), Kolkata, to study on what kind of changes could be made in the design of the gates for the passage of Pulasa fish upstream and downstream of the river.
“It is perhaps the first time that the CIFRI studied the physiology and behaviour of Pulasa fish in choosing its path in the river and designed a specialised Fish Ladder Gate to be erected on one of the piers of the spillway to enable the unhindered passage of fish during the season,” the chief engineer said.
According to Satish Babu Angara, general manager of Megha Engineering and Infrastructure Limited which is executing the project, the fish ladder gate is about 252 metres in length and has three vents at various levels of the spillway so that the fish could move freely even if water levels keep changing.
“We have made this arrangement in the second pier of the dam, keeping in view the path of the Pulasa fish. The fish ladder gate can be adjusted according to the water level,” Satish said.
Each vent of the fish ladder gate will be of six feet height and four feet in width, which will provide enough space for the fish to pass through during the season, the chief engineer said.
The project works are moving at a fast pace now. The erection of 52 spillway pillars, each measuring a height of 52 metres, of the dam was completed on Thursday. “We shall complete the erection of gates shortly, apart from bridge and slab works on the spillway by June,” Satish said.
