The whale rescue effort on Tasmania's west coast is turning to the gruesome task of disposing of the animals which could not be saved.
Three days on from 230 pilot whales stranding on Ocean Beach, near Macquarie Heads, authorities will on Friday begin the job of "recovery and disposal".
Of the 40 whales still alive when authorities arrived on Wednesday, rescue teams were able to return 32 to deeper water.
About 10 became stranded again overnight, with one dying and another having to be euthanased.
Authorities are still trying to rescue another three pilot whales in a remote area of the beach but say a cool weather change will help their chances of survival.
Tasmania Parks and Wildlife Service incident controller Brendon Clark said the rescue operation, on the whole, had been "pretty successful".
The rescue effort involved animals — in some cases weighing up to two and a half tonnes — being lifted into vehicles, by people and heavy equipment.
They were then transported down the beach to a more sheltered area of coastline, where they were put back into the water in a sling and attached to boats, which then towed them out to deeper water.
After refloating the surviving whales, the final phase will begin informed by what could have been done better at the last mass stranding event along the same stretch of coast.
"Last time we did leave some carcasses in situ on Ocean Beach and were hoping for a natural decomposition. But that didn't occur in a satisfactory time frame," Mr Clark said on Thursday.
In 2020, he said, authorities "went for a burial method to try and alleviate that stench which was emanating from out on Ocean Beach".
But this time, the dead whales will be towed out into the deeper waters of the Indian Ocean, past the shelf drop-off which begins about 40 kilometres off the coast, to "reduce the risk of the carcasses coming back and washing up on the beach".
"Our first option will be long-lining the carcasses out to deep ocean utilising the vessels that have been so readily provided by the aquaculture companies," Mr Clark said.
"We'll get them out into deep ocean as far out as we can, in suitable weather conditions. At the moment, the [best] weather conditions look like being Sunday."
Sea disposal not likely to attract sharks
Mary-Anne Lea, professor in marine/polar predator ecology at the Institute of Marine and Antarctic Studies, said dumping the carcasses at sea was a "trade-off between managing the risk between human health and recreational use of those areas".
"Obviously whales are large and they smell, and they take a long time to decompose," she said.
"In terms of taking them out to sea where they can float or sink and decompose naturally, that's a good thing because it's a resource for other animals in the ocean."
Kris Carlyon, from the Department of Natural Resources and Environment Tasmania, said the disposal method was not likely to pose a threat from increased shark activity.
"That will be some distance offshore, winds and currents and swell conditions will spread those animals apart quite rapidly," he said.
"There is a lot of biomass out there in the ocean already and we're not really significantly adding to that.
"Yes, lots of things will get a pretty good feed out of this, but carcasses will spread rapidly across a pretty huge distance."
In warmer climates, carcasses of larger species had been known to expand and explode from the build-up of natural gas, but Mr Carlyon said the smaller pilot whales were not at risk of exploding.
Hope for last meal clues
Dr Carlyon said that before the disposal operation began, necropsies of dead whales would hopefully reveal clues as to why they came into shore.
"One theory [is] that they are potentially chasing prey," he said.
"These guys do feed on squid. That could have brought them into shore … and they came unstuck because of that. That will be part of the post-mortem investigation.
"We'll be looking at stomach contents, what these animals have been feeding on in the last few days. That may offer up some some additional clues."
On Thursday, Dr Carlyon said measures such as acoustic devices to ward away whales from future strandings had been looked at, but so far had not proved "feasible" in practice.
Tuesday's stranding of pilot whales came a day after 14 sperm whales came aground at King Island, off Tasmania's north-west coast.
