Australian rescuers were hoping to rescue 20 more pilot whales stranded off the coast of the island of Tasmania on Thursday after 70 were successfully returned to the ocean.
“We are convinced that most of these animals have escaped,” said Kris Carlyon, a wildlife biologist with the Australian Marine Conservation Program on Thursday.
Tasmania’s largest massive stranding saw 470 whales trapped on a sandbar on the island’s west coast this week. While the latest rescue efforts are underway, crews must also remove the carcasses of 380 whales that have died.
The bodies will be dumped at sea, preferably, over the next few days before swelling and floating in the tides, said Nic Deka, regional director of the Tasmanian Parks and Wildlife Service.
“They will present a significant navigation hazard if we don’t get them under control,” Deka said.
The group of around 270 whales stuck on a sandbank were first detected on Monday. Another 200 whales were found about six miles from the coast on Wednesday.
Once stranded, whales only have a few days to survive because their organs – which are no longer suspended by the water – are damaged.
The cause of the massive grounding remains to be determined.
The event is not uncommon and twice as many strandings have been recorded in New Zealand, Carlyon said. But the current grounding set a new record for Australia, with the country’s last record set in 1996 with 320 pilot whales stranded in the town of Dunsborough.
“There’s not much we can do to prevent this from happening in the future,” Carlyon said earlier this week.
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Pilot whales have strong social bonds and even if only a few members of a group deviate from their course, others often follow. This makes re-grounding possible, as the rescued animals attempt to reconnect with the rest of the pod.
But Carlyon said that on Thursday none of the rescued whales – which were marked to be identifiable – returned to the shoreline where the carcasses piled up.
Four whales alive but weakened and suffering from the stranding will need to be euthanized, Carlyon said.
“These are animals that we gave a chance to, we tried to release them and they didn’t do well,” he said. “We don’t think trying to release them again is a viable option. “
The Associated Press contributed to this report.