At least 14 sperm whales have died after becoming stranded on King Island, off the north-west coast of Tasmania.
A spokesperson for the Department of Natural Resources and Environment said it appeared all the whales were "young males and were dead at the time the stranding was reported on Monday afternoon".
Svetlana Jacobson heard about the stranding yesterday.
"My family and I went and saw 14 whales along the beach," she said.
"They lay there for quite a long time as they already had a specific smell and blood around."
Resident Marion Fogarty said while there had been strandings on the island in the past, she wasn't aware of it happening in this location.
"Every year or two we do get beachings, whether it's a sperm whale or different whales," she said.
"It was pretty horrific actually to see it ... and it was a pretty sad thing really."
Marine Conservation Program wildlife biologists and a vet are on their way to the island to investigate the stranding.
A plane will be used to check if there are other whales in the area.
Whale stranding 'a complete mystery'
King Island has had its fair share of whale strandings over the decades, but wildlife scientist Vanessa Pirotta said what caused them remained "a complete mystery".
"We simply do not know why this happens," she said.
"That's the million-dollar question every time this kind of event happens."
Dr Pirotta said the latest stranding may have been caused by a navigation error or the group following one whale heading towards the shore.
"There could be something else that might have driven them to the area, we just don't know," she said.
"But the key thing here is that any stranding can contribute to science.
"Now authorities will undertake a necropsy, which is an animal autopsy, to try and understand what these animals might have been up to, but also to learn more about them."
A department spokesperson said it was not unusual for sperm whales to be seen in the area.
"While further inquiries are yet to be carried out, it is possible the whales were part of the same bachelor pod," they said.
Carcasses will be left to rot
Wildlife biologist Kris Carlyon is helping coordinate the response to the stranding but said there were few feasible ways to remove or bury the bodies.
The rocky coastline restricts access of machinery and towing the carcasses out to sea could see them "wash up somewhere, probably more problematic".
"The preference for us is to let them decompose naturally," Dr Carlyon said.
"All that nutrient then goes back into the ecosystem and feeds a whole bunch of other animals."
The decomposition process could take months but authorities are warning the public to stay away as the carcasses may carry diseases or crush someone as they move with the tides.
Residents have been asked to keep their distance.
"It's certainly an offence to interfere with the carcass of a whale and to take any product from that animal. There's also human safety risks, these are big animals," Dr Carlyon said.
Surfers and swimmers are also asked to avoid the area, with a risk of the carcasses attracting sharks.
Tasmanian coast 'a bit of a whale trap'
While the latest stranding was "a relatively big one", it pales in comparison to the hundreds of pilot whales that washed up on mainland Tasmania's west coast in 2020.
Dr Carlyon said the state's "quite complex" coastal topography "can often act as a bit of a whale trap".
"Tasmania is a bit of a hot spot for mass whale strandings," he said.
"Our coast is very close to the shelf edge where it drops off and a lot of these species forage in the deeper waters off the shelf edge.
"The most common cause of stranding is simply misadventure. So the animals get themselves into trouble in a complex bit of coast or get themselves caught out in a low tide."
Sightings of free-swimming or stranded whales and dolphins can be reported to 0427 WHALES.
