The majority of a 470-strong pod of pilot whales found stranded in Australia has died, officials said on Wednesday. Rescuers are trying to save the small group of pilot whales that are still alive.
The group, which is the biggest beaching in the country’s modern history, were first spotted on a wide sandbank during an aerial observation of Macquarie Harbour in Tasmania state on Monday.
After two days of challenging rescue attempts, state marine scientists said at least 380 of the long-finned pilot whales had died.
By late Wednesday, around fifty of the mammals were freed but experts said there was a high likelihood they would return as many did during the rescue attempt a day earlier.
The chance of survival for the remaining 30 stranded and still alive pilot whales, a species of oceanic dolphins that grow to 7 meters (23 ft) long and can weigh up to 3 tonnes, is small.
“As time goes on, they do become fatigued, and their chance of survival reduces,” Parks and Wildlife regional manager Nic Deka said. “We do expect to rescue more, but increasingly our focus is what do with the carcasses.”
The refloating process involves four or five people per whale standing waist-deep in freezing water, attaching slings to the animals so they can be guided out of the harbor by a boat.
The stranding, about 200 kilometers (120 miles) northwest of the state capital Hobart, is the biggest on record in modern Australia and one of the largest in the world, drawing attention to a natural phenomenon that remains a mystery to scientists.
Marine mammals and ship navigation
“It’s certainly a major event and of great concern when we potentially lose that many whales out of a stranding event,” said Peter Harrison, a professor at the Southern Cross University Whale Research Group.
“Quite often, we only get to really see them when there are bad outcomes, such as this stranding event. We absolutely need some more investment in research to understand these whales in Australian waters.”
Olaf Meynecke, a whale researcher at Australia’s Griffith University, said pilot whales use sophisticated sonar to find prey and for orientation, so some theories link strandings to changes in electromagnetic fields.
“These changes can be caused by solar storms or earthquakes (seismic activities), but there is also a strong connection between active sonar, for example naval sonar, and dolphin strandings including pilot whales,” Meynecke said.
Active sonar, the transmission equipment used on some ships to assist with navigation, is damaging to the health and lives of some marine mammals.
In 1996, 320 pilot whales washed up on the coast of Western Australia, which was then reported to be the country’s biggest mass stranding. About 600 pilot whales beached in nearby New Zealand in 2017.Donate