Wildlife rangers said a pod of about 80 pilot whales beached themselves at Marion Bay late Tuesday, just hours after nearly 60 of the animals died in an earlier mass stranding in the same spot.

An Australian Defence Force (ADF) spokesman confirmed two naval ships had been operating in the area using short-range, high-frequency sonar as they searched for remnants of an historic ship wreck.

Greens senator Christine Milne said an investigation should be launched into whether the sonar had contributed to the strandings.

"We know that high-intensity sonar, which some military vessels use, can disrupt the navigation system of whales and dolphins," she told reporters.

However, the ADF said the two ships were anchored far to the west in Hobart when the first stranding occurred and their presence had no bearing on the second.

"The later presence of the two ships in the stranding area is purely coincidental and is considered unrelated to the cause of the strandings, which are considered by many to be a natural phenomena that occurs regularly in the Tasmanian area at this time of year," he said.

Tasmania Parks and Wildlife Service spokeswoman Liz Wren said dozens of volunteers and wildlife officials were involved in the rescue effort.

"When we got here this morning there were about 70 dead whales scattered over a stretch of about a kilometer (half a mile) of beach," she said.

"We've been able to put eight back in the water, but I'm afraid the rest died," she told AFP by mobile phone from the beach. "It's really terrible."

Pilot whales, which are actually a large species of dolphin that can grow up to six metres (20 foot) long, frequently beach themselves in a phenomenon that remains a mystery to scientists.

Another parks and wildlife official, Ingrid Albion, said it appeared that one disorientated pilot whale in the first group may have led the entire pod to a stranding.

"Maybe they've come in close looking for food, maybe the tide's been a bit different," she said on Australia Broadcasting Corporation radio.

"They use sonar so they can get confused when they come into sandy beaches," she said.

"Only one of them has to get in trouble and make a wrong turn and they'll actually call the rest of the pod to them."

On Tuesday, rescuers managed to push 10 of 67 stranded whales back out to sea.

Tasmania's rugged coastline has one of the highest stranding rates in the world.

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