A decision to kill 48 pilot whales found stranded on a remote Stewart Island beach had been difficult but there was no alternative, the Department of Conservation (DoC) says.
Trampers found a pod 107 whales dead and dying at a beach near Cavalier Creek yesterday.
The whales were stranded high up on the beach with the tide just starting to recede and about half of them were dead, DoC said.
It was decided to euthanase 48 whales as there was no way of saving them.
DoC had just five staff available and with the tide on its way out, there was little hope of keeping the animals alive until enough rescuers could be flown in to help.
"We were quickly aware that it would be at least 10 to 12 hours before we could attempt to refloat them and that given the hot, dry conditions many more would soon perish," a spokesman said
There was also a storm warning which would have added to the dangers of refloating the whales.
"We were worried we would be endangering the lives of staff and volunteers," he said.
The whales would be left to decompose naturally on the beach.