Twelve pilot whales died on Thursday and another 16 had to be euthanized after a pod stranded on Farewell Spit, at the top of New Zealand’s South Island, the Department of Conservation said.

Department spokesman Hans Stoffregen said it was too dangerous to try to refloat the survivors, who were sick, on the next high tide at midnight and they were unlikely to survive until the next high tide 12 hours later.

Mr. Stoffregen said the decision to put down the survivors was made after discussions with the Project Jonah whale protection organisation and local Maori tribe leaders.

He said earlier that the whales were washed up high on the beach by an unusually high tide and they had to be sick because they would not normally die so quickly.

Strandings are common on the 24-kilometre long sandspit and whales often beach themselves again after being refloated.