More than 140 pilot whales have died after becoming stranded on a remote New Zealand beach.

A hiker discovered 145 pilot whales in two pods just over a mile apart late on Saturday on Stewart Island.

About 75 were already dead and conservation workers decided to euthanise the others due to their poor condition and remote location.

Only about 375 people live on Stewart Island, which is also called Rakiura. The whales were found at Mason’s Bay about 22 miles from the main township of Oban.

“You feel for the animals, it’s just a really sad event,” said Ren Leppens, the Rakiura operations manager for the Department of Conservation.

“It’s the kind of thing you don’t want to see. You wish you could understand the reasoning why the whales strand, so you could intervene.”

Leppens said the whales were half buried in sand and not in good health, indicating that they had been there for perhaps a day before they were found.

He said staff shot the whales and the carcasses would be left where they were for nature to take its course.

Meanwhile, on Sunday, 10 pygmy killer whales were found stranded at Ninety Mile Beach on the North Island in an unrelated event. Two have since died, and staff plan to try and refloat the remaining eight.

Whale strandings are relatively common in New Zealand during the Southern Hemisphere spring and summer.

It is believed strandings can be caused by a number of factors, such as the whales trying to escape predators, falling ill, or navigating incorrectly.