Up to 145 pilot whales have stranded and died on a remote beach on Rakiura/Stewart Island over the weekend.
A heartbreaking decision was made to euthanise the remaining whales due to their poor condition and hard to access location, DoC Rakiura operations manager Ren Leppens said.
Pilot whales lie beached at Mason Bay, Rakiura on Stewart Island, New Zealand.
There were two pods stranded at the southern end of Mason Bay, approximately 2km apart.
The "heart-breaking" decision to euthanise around 70 pilot whales on Stewart Island at the weekend was "not taken lightly", Department of Conservation (Doc) staff say.
The two pods were stranded at Mason Bay on the remote southern Stewart Island, approximately 2 km apart, on November 24.
The DOC also announced that it was working with a local Maori tribe on the "next steps". Factors could include sickness, navigational error, geographical features, a rapidly falling tide, being chased by a predator, or extreme weather.
The department said the two events were unlikely to be related.
NEW ZEALAND DEPARTMENT OF CONSERVATION Almost half of the whales were already dead by the time they were discovered.
A sperm whale which beached in Doubtless Bay died overnight on Saturday, while the body of a dead female pygmy sperm whale was found at Ohiwa on the west coast of the North Island.
The sheer number of pilot whales made for a startling sight on an island of just 378 people.
Two of the animals have died, but the authorities launched an appeal on Facebook to encourage the public to help "re-float" the surviving eight whales on Tuesday morning. The largest recorded whale stranding in New Zealand's history occurred on the Chatham Islands in 1918, when around 1,000 pilot whales came ashore, according to The Guardian.
"What we do find with nearly every stranding, there's more than one reason. sometimes we can put it down to a combination of four, five, even six different factors that may have led to the stranding".