Rescuers release a stranded pilot whale back in the ocean at Macquarie Heads, on the west coast of Tasmania on September 22, 2022. Image Credit: AFP

Ocean Beach, Australia: Almost 200 whales have perished at an exposed, surf-swept beach on the rugged west coast of Tasmania, where Australian rescuers were only able to save a few dozen survivors Thursday.

After an arduous, day-long effort in difficult conditions, state wildlife services said just 32 of the 226 beached long-finned pilot whales were strong enough to be rescued.

“We’ve been refloating those whales that have been deemed suitable for release back to sea,” Sam Thalmann, a marine biologist, told AFP.

“Every whale that has been released has been tagged,” he said. “There may be a few that restrand unfortunately, but we expect that by far the majority will head out to sea.”

Locals had covered some of the mammals with blankets and doused them with buckets of seawater to keep them alive until more help arrived.

But many of the whales were too far gone.

By nightfall, scores of the glossy black whales were strewn along Ocean Beach, their carcasses pock-marking the waterline where the frigid southern ocean meets the sand.

“Unfortunately we do have a high mortality rate on this particular stranding,” said state wildlife operations manager Brendon Clark.

“The environmental conditions, the surf out there on the exposed west coast, Ocean Beach, is certainly taking its toll on the animals.”

Efforts will now turn to the considerable task of disposing of the whale bodies safely.

If left in shallow waters or on the beach, they could attract sharks and can carry disease.

“There is a lot more work to be done with the carcass disposal,” said Thalmann, who added that “valuable biological samples” would need to be collected from the animals.

Those could help scientists understand how and why “the animals strand at this location”.

Rescuers release a stranded pilot whale back in the ocean at Macquarie Heads, on the west coast of Tasmania on September 22, 2022. Image Credit: AFP

“There (are) certainly some local characteristics that lead to this spot being repeatedly a site for mass whale stranding.”

Two years ago, Macquarie Harbour was the scene of the country’s largest-ever mass stranding, involving almost 500 pilot whales.

More than 300 pilot whales died during that event, despite the efforts of dozens of volunteers who toiled for days in Tasmania’s freezing waters to free them.

Clark said the conditions of the latest stranding were tougher for the whales than two years ago, when the animals were in “much more sheltered waters”.

Distress signals

Scientists still do not fully understand why mass strandings occur.

Some have suggested pods go off track after feeding too close to shore.

Pilot whales - which can grow to more than six metres (20 feet) long - are also highly sociable, so they may follow pod-mates who stray into danger.

That sometimes occurs when old, sick or injured animals swim ashore and other pod members follow, trying to respond to the trapped whale’s distress signals.

Others believe gently sloping beaches like those found in Tasmania confuse the whales’ sonar, making them think they are in open waters.

The latest stranding came days after a dozen young male sperm whales were reported dead in a separate mass stranding on King Island - between Tasmania and the Australian mainland.

State officials said that incident may have been a case of “misadventure”.

Strandings are also common in nearby New Zealand.

There, around 300 animals beach themselves annually, according to official figures, and it is not unusual for groups of between 20 and 50 pilot whales to run aground.

But numbers can run into the hundreds when a “super pod” is involved - in 2017, there was a mass stranding of almost 700 pilot whales.

Whale strandings: Five questions answered

Karen Stockin, a whale stranding expert at New Zealand’s Massey University, answers five key questions.

What causes mass strandings?

Scientists are still trying to work that out. They do know that there are multiple types of stranding events, with several explanations that can overlap. The causes can be natural, based on bathymetry - the shape of the ocean floor - or they can be species-specific.

Pilot whales and several smaller dolphin species are known to regularly mass strand, especially in the southern hemisphere, according to Stockin. In some instances, a sick whale headed towards shore and a full group unwittingly followed them.

Does it happen in certain areas?

There are a few global hotspots. In the southern hemisphere, Tasmania and New Zealand’s Golden Bay have seen several instances, and in the northern hemisphere, the United States bay of Cape Cod, Massachusetts, is another hotspot.

In those areas, there are similarities between the topography of the beaches and environmental conditions. For example, Cape Cod and Golden Bay share a prominent narrow coastal land feature and shallow water with large tidal variations. Some people call such areas “whale traps” because of the speed at which the tide can recede.

Are strandings becoming more common?

Possibly. Strandings are natural phenomena and have been documented since the days of Aristotle. The health of the oceans has, however, deteriorated in recent decades.

Strandings could become more common as human use of the seas, shipping traffic and chemical pollution all increase.

Epizootic diseases - outbreaks of sickness that affect a specific animal species - could also lead to more. But there is still much to understand about the phenomenon, Stockin said.

Is climate change a factor?

Research on how climate change is affecting marine mammals is still in its infancy. Experts know that climate change can give rise to changes in prey and predator distribution. For some species, this may result in whales coming closer to shore.

For example, recent research based on current climate prediction models suggests that by the year 2050, the distribution of sperm whales and blue whales in New Zealand could vary considerably.

Can strandings be prevented?

Not really. As strandings occur for a multitude of reasons, there is no one-size-fits-all solution. But experts say that by better understanding whether and how human-induced changes are causing more mass strandings, solutions could be found.