Hundreds of pilot whales that swam into the shallow waters of a New Zealand bay died overnight after they got stuck in the waterway and beached themselves on the coastline.

More than 500 rescuers tried frantically to send the pilot whales back out to sea, but at least 250 died in what officials called one of the worst whale strandings in New Zealand?s history.

Attempts to refloat the remaining whales during high tide met with partial success. About 50 whales had swum out of the bay after high tide according to the department of conservation, but as many as 90 others had re-beached themselves by Friday afternoon. Volunteers said they would try to refloat the stranded whales again on Saturday.

Whale strandings at Farewell Spit, at the northern tip of New Zealand?s South Island, happen most years, Kath Inwood, a ranger, told The Associated Press. But the high number of whales trapped this year has surprised conservation officials.

The whale stranding was the largest in the country since 1985, when 450 were stranded near Auckland. New Zealand has one of the highest rate of whale strandings, which are believed to occur when the mammals, who are known for their social bonding, make navigational mistakes while chasing prey, escaping predators or trying to protect sick members of the group.

source: https://www.nytimes.com/2017/02/10/world/australia/whales-beach-new-zealand.html?_r=0