Hamelin Bay: Nearly 150 beached whales die in Australia Published duration 23 March 2018

media caption Over 100 whales die in mass stranding in Australia

Only six whales have survived a mass stranding of pilot whales on the coast of Western Australia.

Their discovery by a local fisherman on Friday prompted a major rescue effort to return them to deeper waters.

However, by nightfall, more than 140 of the whales had died, with deteriorating weather conditions and the threat of frenzied sharks impeding efforts.

More than 100 volunteers, wildlife personnel and others came to the aid of the beached pilot whales, a species known to strand en masse.

"I've never seen anything like it, seen so many whales beached like this," one tourist told the Associated Press news agency.

"Unfortunately, most of the whales beached themselves on dry land overnight [on Thursday] and have not survived," Parks and Wildlife Service spokesperson Jeremy Chick said in a statement.

The rocky beach terrain, dead whales surrounding the survivors and rough seas were challenging factors in moving the surviving whales, officials said.

Mr Chick said there was a risk the surviving whales might come back into shore and re-strand.

"This has often been the case in previous mass strandings," he added.

'A mystery of nature'

Scientists do not know exactly what causes whales to beach themselves.

image copyright Western Australia Government image caption Most of the 150 animals stranded were dead by the end of the day

Experts have said stranding can occur when whales are sick or injured, or make navigational errors, particularly along gentle sloping beaches.

Sometimes beached animals can send out distress signals that attract other whales to become stranded.

In 1996, about 320 whales became beached in Western Australia's largest stranding.

media caption Scientists have been carrying out experiments to measure the effects of human-made noise