More whales rescued in Tas mass stranding

Almost 90 pilot whales have been saved from a mass stranding on Tasmania's west coast, as authorities make grim plans to dump hundreds of carcasses at sea.

The largest beaching on record in Australia has killed 380 of the 470-odd whales involved in the stranding.

At Thursday afternoon, rescuers had freed 88 whales from sandbars at Macquarie Harbour and successfully guided them into deeper water.

Their focus is turning to removing decomposing carcasses, which could pollute the harbour, attract sharks and pose a navigation risk.

"Our aim will be to do it as quickly as possible but realistically it could take several days," parks and wildlife incident controller Nic Deka said.

Weighted buoys and pens are being used to contain the carcasses, which will likely be removed from the harbour on boats or by towing from Friday if conditions allow.

Crews on Thursday discovered several more whales healthy enough to save and say about 20 can still be rescued.

"Whenever we've got live animals that have a chance, and we have the resources, then we'll certainly give it a go," Mr Deka said.

Despite the death toll, wildlife biologist Kris Carlyon said rescuers were pleased with how many whales they could help.

He said the pod was likely to re-form at sea but may face some challenges if their older leading females are missing.

"If they've lost those older matriarchs with a built-up knowledge of the area, then they may need to learn some new behaviours," he said.

"If they remain at sea, hopefully they'll regain their normal behaviour."

An initial stranding of 270 whales was discovered on Monday, with a further 200 found dead on Wednesday morning.

Four whales have been euthanised, with Mr Deka saying the operation was taking an emotional toll on those involved.

"Everyone's tired, feeling the fatigue. The people on site working on the water are those doing it hardest," he said.

Experts believe the pod was brought close to shore by food before getting caught up in the complex harbour heads.

The previous biggest stranding in Australia was in 1996 when 320 pilot whales beached at Dunsborough in Western Australia. Only about 20 survived.