A pod of 230 pilot whales were found stranded on Tasmania’s rugged west coast on Wednesday, with Australian officials saying only half appeared to be alive.

Aerial images showed a devastating scene of dozens of shiny black mammals scattered across a long beach and stuck at the waterline where the frigid Southern Ocean meets the sand.

Locals covered survivors with blankets and poured buckets of water over them to keep them alive, while other nearby whales struggled to free themselves, leaving even more dead.

The whales were “stranded near Macquarie Harbour,” the state Department of Natural Resources and Environment said.

“It seems that about half of the animals are alive.”

Officials said marine conservation experts and workers with whale rescue gear were on their way to the scene.

They will attempt to refloat animals strong enough to survive, likely dragging the carcasses out to sea to avoid attracting sharks to the area.

It’s been almost two years to the day since Macquarie Harbor was the scene of the country’s largest mass stranding, involving nearly 500 pilot whales.

More than 300 pilot whales died during this stranding, despite the efforts of dozens of volunteers who struggled for days in Tasmania’s freezing waters to free them.

The cause of the mass strandings is still not fully understood.

Scientists have suggested they could be caused by pods going off track after feeding too close to shore.

Pilot whales – which can grow up to six meters long – are very sociable and can follow podmates who find themselves in danger.

This sometimes happens when old, sick, or injured animals swim ashore and other members of the group follow them, trying to respond to the trapped whale’s distress signals.

Others believe gently sloping beaches like those in Tasmania confuse whales’ sonars and make them think they’re in open water.

The news came just hours after a dozen young male sperm whales were reported dead in a separate mass stranding on King Island – between Tasmania and mainland Australia.

The deaths of the young whales could be an “accident,” wildlife biologist Kris Carlyon of the state’s conservation agency told local newspaper Mercury.

“The most common reason for stranding events is an accident, they may have foraged near shore, there may have been food, and they may have been caught by a low tide,” Carlyon said.

“That’s the theory at the moment.”

Strandings are also common in nearby New Zealand.

According to official figures, around 300 animals strand there every year and it is not uncommon for groups of 20 to 50 pilot whales to run aground.

But the numbers can run into the hundreds when a “supercapsule” is involved – in 2017 there was a mass stranding of nearly 700 pilot whales.