The last of nearly 100 whales that beached on the southwestern Australian coast were euthanized Wednesday after a second day of frantic, but unsuccessful efforts to rescue them, authorities said.
The pod of long-finned pilot whales stranded themselves Tuesday on Cheynes Beach east of the former whaling station of Albany in Western Australia state, south of the capital Perth.
The remaining 45 were euthanized Wednesday after efforts to lead them to deeper water failed. The survivors continually returned to the shallows, the Western Australia Parks and Wildlife Service said in a statement late Wednesday.
"Sadly, the decision had to be made to euthanize the remaining whales to avoid prolonging their suffering," the service said.
"It was a difficult decision for all involved, however the welfare of the whales had to take precedence," it added.
The service thanked the officials and volunteers who helped with the attempt to save the whales. A storm lashed the beach with wind and rain Wednesday afternoon, and two volunteers were treated by paramedics for hypothermia, Australian Broadcasting Corp. reported.
Peter Hartley, a manager of the Department of Biodiversity, Conservation and Attractions who oversaw the response, on Thursday described the decision to euthanize the survivors as "incredibly hard."
"It was a considered and well thought out decision. And you know, we thank the support of the ... veterinarians that assisted with the assessments and the advice that they gave me to make that decision," Hartley added.
Wildlife experts speculated the beaching could be an indicator of stress or illness within the pod, but said the reasons would likely remain a mystery.
Pilot whales are highly social animals and maintain complex familial relationships with their pods from birth.
Drone footage released by the state government showed the whales clustering and forming into a heart shape before stranding themselves on the beach.
Hartley said samples would be taken from the whale carcasses for analysis before they are buried at an inland location.
"We're getting requests from around the world from scientists wanting the video footage of them all huddled together on the Tuesday," Hartley said.
"We're going to be learning a lot about the behavior. We're also going to be learning a great deal about the genetics, the make up of that group, were they related?" he said.
The incident was reminiscent of one last September, in which some 200 pilot whales died after a pod stranded itself on the remote west coast of the island state of Tasmania, off Australia's southeastern coast.
The following month, nearly 500 pilot whales died after stranding themselves on two remote beaches in New Zealand.