Three Mass Whale Strandings In A Month -- But Why Is It Happening?

Hundreds of pilot whales have died in three mass strandings this month, but what causes these highly intelligent animals to become beached?

Whale strandings are not a new phenomenon, but in recent weeks there has been a spate of them.

Beaching incidents in New Zealand, Victoria and the Falkland Islands are rare, according to Catherine Kemper, a senior researcher in mammals at the South Australian Museum who specialises in whales and dolphins.

Why have there been so many lately?

Scientists don't actually know why there's been an increase in the number of strandings in such a relatively short amount of time.

Not enough is known about the migration patterns of pilot whales to make an accurate assessment of why there has been a recent spate of mass strandings, Kemper told 10 daily.

Mass stranding of about 140 pilot whales on Stewart Island in New Zealand on Saturday. Image: NZ Department of Conservation.

A pod of 27 pilot whales and a humpback whales washed up on a remote beach at Croajingolong National Park in Victoria on Tuesday. Despite the best efforts of rescuers, all died.

Shallow continental shelves around the coast of Victoria and around to South Australia mean it is incredibly rare for whales to become beached, as they tend to avoid the area for deeper waters.

"It's incredibly unusual for a mass stranding to happen in Victoria," Kemper said.

"But we don't know why, it's incredibly hard to research them, so we don't know much about them."

Rescuers attempt to float whales in New Zealand. Image: AAP

More than 140 pilot whales died in New Zealand after stranding themselves on a beach in the country's far south on Saturday night.

READ MORE: Mass Stranding Kills 145 Pilot Whales In New Zealand

Earlier in November, 56 long finned pilot whales died in the Falkland Islands.

Which species are most likely to beach themselves?

Mass beaching only occur in whale species that are highly social and live in the deep parts of the ocean.

"One theory that has been put forward is in some areas the magnetic fields are out of whack and this could affect how they navigate," Kemper said.

Researchers are not sure why whales beach themselves. Image: Getty Images

Other ocean mammals, such as dolphins which live closer to the coast, aren't known to become stranded.

"They're used to swimming near the coast and know the area," she said.

How do they end up getting stranded?

Mass beachings can occur when whales become confused and disorientated since their sonar does not work in shallow waters.

"They send out sound waves and they bounce back so they can get an idea of what the coastline is doing," Dr Derek Spielman, senior lecturer in Veterinary Pathology at the University of Sydney, told 10 daily.

"If you have a very shallow, sloping beach, the sonar does not return from that."

The main theory is these sonar readings confuse the whales, and they think they are swimming into open water.

Instead, they will swim on to the shore and become beached.

Rescuers stand with a pigmy killer whale after it was transported to Rarawa Beach from Ninety Mile Beach in the far north of the North of New Zealand. Image: Department of Conservation

On occasion, if one or two whales are confused and get themselves in to trouble, the other members of the pod will try and help them and become beached themselves.

Single whales will often swim into shore for safety, but will mistakenly become beached said Spielman, who has attended a number of strandings.

"They do not want to drown and they are scared of sharks," he said.

READ MORE: Whale Washes Up On Beach With 115 Plastic Cups In Stomach

READ MORE: Dramatic Vision Of A Beached Whale Rescue

But sick whales becoming beached can lead to their pods following, becoming a mass stranding.

"The other members of the pod could follow the sick one because of the strong emotional connection with it," Spielman said.

Feature Image: Getty