A pod of about 230 whales has been stranded on Tasmania’s west coast, prompting a rescue mission from marine conservationists who believe about half the mammals are dead.

The mass stranding is happening on Ocean Beach near Macquarie Harbour, south of Strahan, and a number of the whales are stuck on a sand flat inside the harbour, according to the Tasmanian government.

They are believed to be pilot whales and it appears about half have died, the Department of Natural Resources and Environment Tasmania said.

The stranding is the second in a matter of days, after 14 dead sperm whales washed ashore at King Island on Monday.

Marine conservationists from the department were on Wednesday heading to the west coast with whale rescue gear in tow.

They would work alongside local police and Tasmania Parks and Wildlife Service staff, the department said.

Marine wildlife experts would look over the scene to work out how they should respond.

The area presented complexities for rescuers and the public would be called on to help if necessary, the department said.

Wildlife biologists and a vet are still investigating how the pod of young males became stranded.

It was quite unusual for sperm whales to wash ashore, Griffith University marine scientist Dr Olaf Meynecke told AAP.

“Have these animals been sick or have they been impacted by something?” Dr Meynecke said.

“We know that there is planned massive seismic activity in the entire area for gas and oil exploration, so I’m not sure if there was any seismic activity.

“There can also be natural geomagnetic changes happening that might impact these animals.”

Warmer temperatures could also be changing ocean currents and moving the whale’s traditional food sources, Dr Meynecke said.

“They will be going to different areas and searching for different food sources.

“When they do this, they are not in the best physical condition because they might be starving so this can lead them to take more risks and maybe go closer to shore.”

It was only two years ago that hundreds of whales died after being stranded at Macquarie Harbour.

The 470 long-finned pilot whales were found beached on sandbars in September 2020 in what was the biggest mass stranding on record in Australia.

It was more common for pilot whales to become stranded because they migrate in large numbers, Dr Meynecke said.

Usually, if one whale becomes stranded the others follow.

“Not because they’re just blindly stupid but because of the emotional connection to the others,” he said.

The natural resources department is guided by an incident manual, which has undergone extensive review since the 2020 stranding, to determine its response.

It is an offence to interfere with a whale carcass.

– AAP