About 145 pilot whales died on a remote beach on Stewart Island in New Zealand over the weekend. The incident is the latest in a recent string of whale strandings and deaths in the country.

According to a Department of Conservation (DOC) spokeswoman, the whales were discovered by walkers late Saturday, scattered along the beach of Mason Bay. The two pods of pilot whales were beached about 1.2 miles apart from each other. Authorities said half of the whales had already died by the time they were found. However, the remaining had to be put down as it would have been difficult to save them.

"Sadly, the likelihood of being able to successfully re-float the remaining whales was extremely low," Ren Leppens of the regional Department of Conservation (DOC) said in a statement. "The remote location, lack of nearby personnel and the whales' deteriorating condition meant the most humane thing to do was to euthanize... However, it's always a heart-breaking decision to make."

The local Maori tribe, Ngai Tahu, is now working with DOC to bless the dead whales and make plans for burial of the remains.

Marine mammal strandings are common on New Zealand shores, according to DOC, which responds to about 85 incidents a year, usually of single animals. Since 1840, more than 5,000 strandings were recorded around the New Zealand coastline.

"Exactly why whales and dolphins strand is not fully known but factors can include sickness, navigational error, geographical features, a rapidly falling tide, being chased by a predator, or extreme weather. More than one factor may contribute to a stranding," the DOC wrote in the statement. 

In another unrelated incident of whale stranding, 10 pygmy killer whales were found stranded on 90 Mile beach in Northland, of which two were euthanized, over the weekend. The DOC said it was planning to carry out re-float attempts for those alive on Monday.

Whale rescue group Project Jonah's spokesman Daren Grover said pygmy whales are a tropical breed and it's very rare to see them in New Zealand waters.

"This is a species we are unfamiliar with," he reportedly said. "Having this number of animals come up together, suggests they are a family pod. They all would be traveling together, living together and socializing together in the ocean."

According to Project Jonah, New Zealand has one of the highest rates of whale strandings in the world, with an average of 300 whales and dolphins beaching themselves every year.

In 2017, more than 650 pilot whales beached themselves along Farewell Spit at top of South Island in two separate mass strandings. One of the strandings involved more than 400 pilot whales, making it the largest of its kind in New Zealand for almost a century. The biggest recorded pilot whale stranding was an estimated 1,000 whales at the Chatham Islands in 1918.