SYDNEY (Reuters) - Australian wildlife rescuers on Sunday said they successfully returned a small number of pilot whales to the ocean after a mass stranding in Tasmania.

Chris Arthur, who coordinated the rescue effort, said 11 of the 64 animals found stranded on the island’s north coast on Saturday were released after a day-long effort which involved relocating them by road to another beach.

Environmentalists said it was unusual to save any whales after such a mass stranding

“We have successfully released 11 animals out to sea,” Arthur told Reuters by telephone. “The last one went out less than 20 minutes ago.”

While the possibility that the animals would strand themselves again could not be ruled out, he said, the hope was that they would instead join up with other pilot whales in the ocean. Some the whales have been tagged and aerial reconnaissance is planned to check on their progress.

“We have had a reasonable outcome. They will form a small pod. We have given them the best chance they have got,” said Arthur, a regional officer with the Tasmanian state parks and wildlife service.

This maternal pod of 64 long-finned pilot whales, around one-third of them juveniles, were found stranded on Saturday along a stretch of Anthony’s Beach at Stanley on the island’s northwest coast, a site where repeated strandings have occurred in the past.

Pilot whales are among the smaller whales, typically up to about five meters in length and dark with a grey underbelly. Their relatively small size may have helped rescuers save them, environmentalists said.

Although most of the pod could not be saved, a team of around 65 people battled throughout much of Sunday to move 12 survivors, including both adults and juveniles, 17 kilometers by road in trailers to nearby Godfrey’s Beach to try to return them to the sea. One whale died during the operation.

Mass strandings of whales occur periodically in Australia and New Zealand for reasons that are not entirely understood. Theories include disturbance of echo-location, possibly by interference from sound produced by human activities at sea, a spokeswoman for the environmental group Greenpeace told Reuters.

In a statement, the state government said satellite trackers had been placed on some of the released whales and a reconnaissance plane would fly over the area on Monday to check on the whales’ progress. Samples are to be taken from the dead whales and a mass burial organized.

Although wildlife officials and volunteers have often tried to save stranded whales, relatively few attempts have been successful.