The beaching of a pod of whales off Tasmania’s West Coast could have been caused by one or two whales going astray, a wildlife biologist says.

Although it may be “impossible to determine” why 270 whales got into difficulty on a sandbank at Macquarie Heads near Strahan, about 190 kilometres from Hobart, Marine Conservation Program wildlife biologist Kris Carlyon said the pilot whale’s social nature led them to influence others.

“They’re a highly social species, so the behaviour, vocalisations et cetera of animals nearby definitely influence the behaviour of others,” Dr Carlyon said.

“That group behaviour is very strong, so all those stranded animals moving and vocalising will be influencing each other.

“But we’re probably never going to go into over the ultimate cause for this [stranding].”

Several rescuers are needed to help return each stranded whale to the water. Photo: Edith Bevin

Rescuers say they have freed 25 of the animals so far, but that number is likely to increase by Tuesday evening.

“Crews are continuing to work so that number will increase before we get to the end of the day” Parks and Wildlife regional manager Nic Deka said.

About a third of the animals are estimated to have died, according to authorities, but a more accurate figure will be provided on Wednesday.

“We haven’t got a tally at this stage,” Mr Deka said.

Authorities are planning to conduct an aerial infrared scan tomorrow to determine exactly how many of the animals have died.

“We’ll do a more formal tally tomorrow morning and hopefully have an updated estimate then.”

Whales ‘guided’ to safety

Rescuers have spent today fine-tuning their approach to returning the stranded animals to sea.

“We settled on a method where we get a sling or a strop placed underneath the whale and that’s attached to a boat, one of the vessels from the fish farms,” Mr Deka said.

“We also have crew in the water. They help to manoeuvre the whale off the sandbar and into the deeper water where it achieves a greater level of buoyancy.”

“Then the boat actually escorts the whale out to the deeper water,” he said.

But Dr Carlyon said there was a risk the whales could return to the channel even after they returned to sea.

“We have seen that in past occasions,” he said.

“It depends on a whole range of factors around animal condition and local environmental factors.

“It’s something we do see. We’re hopeful that that’s not going to be the case, but it wouldn’t be unexpected if some animals did restrand.”

One of the rescued whales has already returned to the area.

“That will be attempted to be released again tonight,” Dr Carlyon said.

By lunchtime on Tuesday, a small number of whales had been freed. Photo: Edith Bevin

Rescue could take ‘days’

Dr Carlyon said rescuers would take some animals from “the most accessible location first, assess their behaviour, see what we’re able to do with them, whether we can shift them in water or whether we’re going to have to trial some other option”.

The operation could take “days”, he said.

“We don’t really know how long this rescue is going to take, so this morning’s phase will be critical in determining what’s possible.

“[The operation] is likely to take days.

Dr Carlyon said in terms of mass strandings in Tasmania, “this is up there with the trickiest we’ve had to deal with”.

He said there were about 40 Department of Primary Industries, Water and Environment staff from across the Strahan area assisting.

“We also have some people from other departments, we have police assisting us, we have a handful of volunteers.”

About 60 people are involved in the rescue effort. Photo: Edith Bevin

Dr Carlyon confirmed the rescuers were receiving assistance from several salmon farming companies, which have facilities in the nearby Macquarie Harbour.

“We got the assistance of the fish farms this morning. They have been generous enough to provide some boats and equipment and some personnel. So we’ll be taking advantage of that and working with them, getting their assistance throughout the day.”

He said there were about 60 people involved in the rescue effort.

Dr Carlyon confirmed the rescuers were receiving assistance from several salmon farming companies, which have facilities in the nearby Macquarie Harbour.

He said there were about a total of 60 people involved in the rescue effort.

–ABC