As many as 145 pilot whales have died after a mass stranding in Mason Bay on Stewart Island.
A hiker reportedly spotted the whales on Saturday and notified Department of Conservation staff at 10.30pm.
There were two pods stranded at the southern end of Mason Bay, approximately 2km apart.
DoC Rakiura operations manager Ren Leppens said half of the whales had already died by the time they were found and due to the condition of the remaining whales and the remote, difficult to access location, the decision was made to euthanise the remainder.
"Sadly, the likelihood of being able to successfully refloat the remaining whales was extremely low. The remote location, lack of nearby personnel and the whales' deteriorating condition meant the most humane thing to do was to euthanise."
Shared in chat by RainbowCat who said "highly suspicious."