A pod of 39 long-finned pilot whales area dead after stranding themselves on a beach at the top of New Zealand's South Island, government conservation officials said Monday. Officers from the Department of Conservation (DOC) euthanized 27 surviving whales early Monday after the stranding on Farewell Spit late Sunday, DOC Golden Bay conservation services manager John Mason said in a statement. "We carefully weighed up the likelihood of being able to refloat them and get them safely back out to sea. But our staff, who have extensive experience in dealing with mass whale strandings in Golden Bay, determined that due to various factors it was unlikely they could be rescued," said Mason. "They have come very high on to the beach in a big tide. The big tides are now reducing, coming in further out from shore, so it would be difficult to get the large animals into deep enough water to refloat them. Strong winds would also hamper any refloat attempt." DOC staff were alerted to the pod of whales on Sunday and monitored them out of concern they might strand, but nothing could be done in darkness to prevent the stranding, he said.