Experts and volunteers worked frantically for a second day on Wednesday to save dozens of pilot whales that have stranded themselves on a beach in Western Australia, but more than 50 had already died.
The 51 long-finned pilot whales were part of a pod of almost 100 spotted off Cheynes Beach near Albany, about 400km south-east of Perth on Tuesday.
Experts from the Western Australia Parks and Wildlife Service and volunteers worked through the night, braving cold temperatures to monitor the whales.
The service said it was working with volunteers to save the remaining 46 whales, with plans to guide them to deeper water during the course of the day.
Footage from the scene showed volunteers, many of them wearing wetsuits, trying to help the thrashing mammals on the beach.
A representative for the Parks and Wildlife Service said it had been "overwhelmed with hundreds of offers of help" but that it had enough volunteers and the public should stay away from the beach for safety reasons.
"The priority focus of the incident management team is to ensure the safety of staff and volunteers and the welfare of the whales," the service representative said.
"The response zone has a range of hazards, including large, distressed and potentially sick whales, sharks, waves, heavy machinery and vessels."
Mass strandings of pilot whales – which can grow to more than six metres in length – are not uncommon in Australia and New Zealand.
Last October, about 500 pilot whales died when they beached on the remote Chatham Islands in New Zealand.
Drone footage released by Western Australia's Department of Biodiversity, Conservation and Attractions showed the whales clustering and forming into a heart shape on Tuesday morning before stranding themselves on the beach.
Macquarie University wildlife scientist Vanessa Pirotta said the drone footage could suggest the whales had become disoriented.
“The fact that they were in one area, very huddled, and doing really interesting behaviours, and looking around at times, suggests that something else is going on that we just don’t know,” she said.
Scientists do not fully understand why mass strandings occur, but pilot whales are highly sociable, so they may follow pod-mates who stray into danger.
Bec Wellard, a marine mammal scientist at Project Orca, said that because of the pilot whales' "strong family bonds", it was important to try to refloat them together.
But she added that, if the surviving whales' health is compromised, an assessment needs to be made as to whether efforts to refloat them "could just be prolonging their suffering".
Reece Whitby, Western Australia's environment minister, said the mass stranding was particularly frustrating because it is not known why the phenomenon occurs.
“What we're seeing is utterly heartbreaking and distressing,” he said. “It's just a terrible, terrible tragedy to see these dead pilot whales on the beach.”
With reporting from agencies.