Why are whales beaching themselves by the dozen in India?

Fishermen of a seaside community on the southernmost tip of India worked overnight to rescue dozens of whales that began beaching themselves Monday evening.

The rescuers from Tiruchendur alerted environmental officials shortly after the mysterious mass casualty event began. While about 36 whales were successfully pushed back to sea by fishermen, at least 45 died. The Times of India reports at least 100 short-finned pilot whales were counted along a 10-mile stretch of beach Tuesday, and the fishermen worked throughout the night to save as many of the mammals as they could.

"On Monday evening there were more than a dozen whales beached at many places on the shore," said S. Thiraviyam, a resident of the nearby town of Manapad, told NDTV. Overnight and throughout the day Tuesday, many of the whales that the fishermen worked so hard to push back into the sea only returned, disoriented, to beach themselves again, according to environmental officials.

“The whales started reaching the shore in groups around 5pm [Jan. 11]. It is very strange. In 1973, when we were boys, we witnessed the same phenomenon,” Rajan, a fisherman, told the Times of India newspaper, who said he did not recall as many whales washing ashore, though 147 whales died in Tamil Nadu after being washed ashore that year.

Local environmental authorities have been left scratching their heads, with no immediate answer, as is often the case when whales beach themselves. Marine biologists remain similarly uncertain why the whales came ashore. 

Local officials have suggested the whales may have come ashore in Tuticorin after traveling thousands of miles from the Pacific.

Some are suggesting that this beaching in Tuticorin could be the result of human activity off the coast, which is adjacent to one of the busiest shipping routes in the world.

“The increase in sound levels from ship traffic, sonic testing and oil drilling interferes with the navigation of the whales which often results in the sort of mass stranding we are seeing in Tamil Nadu,” Siddharth Chakravarty of Sea Shepherd Global, a marine conservation organization, told Quartz. “Whales are also very social and often entire pods will follow individual whales closer to shore, which can result in the entire pod stranding itself.”

Short-finned pilot whales in particular are exceptionally social. Biologically from the dolphin family, they are comparable in intelligence to bottlenose dolphins, and are rarely seen alone. In fact, it is their sociability and robust family and pod structures that make this one of the species prone to beach themselves most frequently.

"It's very strange and we are examining the whales," local forest officer S.A. Raju told Agence France Presse. "We found some of the whales are still alive and struggling for their lives.