Pilot whales can grow up to seven meters long and weight three tons.
"Most of them appear to be dead but we will wait for advice from the ground crew before we make a final call on what we do".
Rescuers raced against the tide on Wednesday (September 23) off the Australian island of Tasmania, to try and save some of the estimated 470 whales stranded in a sandbank. "We will continue working while there are still alive animals on site".
Officials have now expanded their search area to see if more whales are stuck nearby.
Carlyon said, "This is definitely the biggest [mass stranding] in Tasmania and we believe it is the biggest in Australia, in terms of numbers stranded and died".
Australia's largest mass stranding had been 320 pilot whales near the Western Australia state town of Dunsborough in 1996.
"They didn't look to be in a condition that would warrant rescue", said Nic Deka, regional manager of Tasmania's Parks and Wildlife Service.
"We'll continue to work to free as numerous animals as we can", Mr Deka said.
Rescuers and experts also warned some of the freed pilot whales may return to the shallow waters overnight and once again become stuck.
Almost 500 pilot whales stranded on Australian island state
While another 200 stranded whales were spotted from a helicopter on Wednesday - less than 10 kilometres (six miles) to the south.
Teams of rescuers managed to save 50 by towing them to deeper water, where they were released, while around 30 more remained beached and fighting for their lives as of Wednesday afternoon.
"It's not necessarily a place that would be obvious for a stranding and the other reason is the water there is very dark so potentially they stranded, were washed back into the water and then washed back into the bay, making them harder to detect", he said.
Wildlife biologist Dr Kris Carlyon said that while the stranding is the worst on record in Australia, worse have occurred elsewhere.
Members of a rescue crew stand with a whale on the sand bar.
And rescue groups are positive that they can conserve more. "We are still very hopeful", Carlyon said.
Diseases, toxins from algae and extreme weather can all cause the whales to swim off course, Hodgins said.
It's not totally clear what triggered the whales to clean up on coast; Carlyon stated whales may have been drawn in after feeding near the coast; or, a couple of whales may have actually roamed too close in "simple misadventure", and the rest of the pod followed.
It surpasses Tasmania's largest mass stranding of 294 long-finned pilot whales in 1935 at Stanley.
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