Forty five whales that washed up along the Tuticorin coast of Tamil Nadu have died, while the remaining 36 were pushed back out to sea by fishermen on Tuesday.
Some of the baleen whales tried to come back to shore even after being dragged back to sea, raising apprehensions that the tragedy could be because of climate change.
Officials said around 250 of the same species were still stranded in shallow waters.
Forest and marine experts have rushed to the coastal town 600 kms from Chennai to explore the reasons for the mass stranding.
"This is an unusual thing, an unusual mortality incident, we have to find the reason," marine scientist Velumani at the fisheries department said.
"There could be many reasons. Navy sonars could have caused it or pollution, the reason is not immediately known and we don't want to speculate," assistant director of Tuticorin fisheries department Amal Xavier said.
"We have to study the health of the stranded whales and also the eco-system. The study would require the help of oceanographic experts also," Velumani said.