The last of nearly 100 pilot whales that stranded themselves on a beach in Western Australia were euthanized on Wednesday after multiple failed attempts to rescue them, authorities said on Thursday.

The long-finned whales beached themselves on Tuesday on the Cheynes Beach, south of the capital Perth.

Forced to make a 'hard decision'

Australia announced on Wednesday that 51 of the whales had already died.

Nearly 250 volunteers joined over 100 wildlife experts in a vain struggle to save the rest of the pod throughout Wednesday.

Eventually, the remaining 45 had to be put down after efforts to lead them deeper into the water failed, said the Western Australia Parks and Wildlife Service in a statement.

Officials said that they were forced to make the "difficult decision" to "avoid prolonged suffering."

"Probably one of the hardest decisions of my 34 years of wildlife management. Really, really difficult," said Peter Hartley, manager of the Department of Biodiversity, Conservation and Attractions.

Whale beaching continues to be a mysterious phenomenon

The phenomenon of whales stranding themselves near Australia and New Zealand is not uncommon. Last October, some 500 pilot whales beached on New Zealand's remote Chatham Islands.

The mammals are highly social animals who often maintain complex familial relationships with their pods from birth.

Drone footage released by the government showed the pilot whales clustering and forming a heart shape before beaching themselves.

Wildlife experts speculate that beaching could be an indicator of stress or illness within the pod, but the reasons will continue to remain a mystery.

Samples will be taken from the whale carcasses for analysis before they are buried at an inland location, said Hartley.

He added that this would contribute a lot to learning the behavior of whales, their genetics and if the mammals were related to each other.

ns/fb (AP, AFP)