Twenty-seven pilot whales beached at the top of the South Island overnight have been euthanised.
The whales were part of a larger pod, which became stranded at Farewell Spit in Golden Bay yesterday.
Department of Conservation's Golden Bay conservation services manager John Mason said 12 of the 39 whales died overnight.
The remaining ones had been euthanised after experts assessed it highly unlikely they could be successfully refloated, he said.
The whales would be moved above the high water mark once the tide allowed it, Mr Mason said.
"They'll be allowed to deteriorate naturally.''
It was not uncommon for whales to become stranded at Farewell Spit. In November 2012, 28 whales died after becoming stranded in the area, and in January that year more than 80 perished after a mass stranding of 99 pilot whales.
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