More than 150 short-finned pilot whales stranded en masse at Hamelin Bay on the west coast of Australia early Friday morning.

Most of the whales did not survive after beaching themselves, according to Jeremy Chick, incident controller at Western Australia's Parks & Wildlife Service.

Roughly 100 authorities and trained volunteers raced to save the 15 whales that were still alive after the stranding. Six of the survivors were returned to sea late in the afternoon.

Chick said moving the surviving whales was difficult logistically due to the rocky beach terrain, the location of dead whales surrounding the live whales and rough seas.

"The conditions are challenging but we are doing all we can to give these animals the best chance of survival without risking the safety of staff and volunteers," he said.

"Once we have moved the whales out we will monitor the situation closely as it is possible the whales will come back into shore and re-strand. This has often been the case in previous mass strandings."

Rescuers said the scene on the beach was distressing, ABC AU reported. UK visitor Barrie Brickle described how the whales repeatedly beached themselves after being pushed back to sea.

"[Volunteers] seem to drag them up onto the beach, get them the right way up and then they seem to revive," Brickle said. "But the ones I've seen that are back in the water, they actually come back around and beach themselves again."

"I watched one of them—it happened three times but still it wouldn't go back to sea."

Short-finned pilot whales inhabit tropical and subtropical waters and may be seen in the hundreds but groups usually number less than 100.

The Parks & Wildlife Service said the migrating mammals have stranded en masse before—nine whales were found dead after stranding at Albany's Ledge Point in November 1984 and 38 short-finned pilot whales stranded in April 1991 at Sandy Point, north of Broome.

However, Reuters reported that the large number this time is unusual.

There is not enough data to determine the animals' conservation status, although they face threats that include getting caught in fishing nets and ending up as by-catch and being hunted.

"Short-finned pilot whales are listed as 'data deficient' on the IUCN Red List of Threatened Species. There is simply not enough information known about their remaining wild populations," Captain Paul Watson, the founder of Sea Shepherd Conservation Society said in 2015 after a pilot whale by hunters in Taiji's infamous cove.

But he noted, "Migrating dolphins and whales are not infinite 'resources;' they are living and vital parts of the ocean eco-system that the nations and government agencies of the world must take action to protect before it is too late."

The largest mass stranding of whales in the state was in 1996 when 320 long-finned pilot whales stranded themselves in Dunsborough.

The reason behind the stranding is currently unclear. Parks & Wildlife Service officers are taking DNA samples from the deceased whales in search of clues for why they strand. Hamelin Beach remains closed and shark alert has been issued for the area, as sharks attracted by the dead whales.