Orcas hunt blue whale in bloody battle of the sea

In rough seas off WA’s south coast, with thunder and lightning cracking overhead, a clash of the titans reached its bloody climax.

A blue whale measuring about 15m long had fought a losing battle against a group of 50 or more orcas.

The clash took place on Thursday morning in 72m of water about 22km offshore — much closer to land than most orca encounters seen off Bremer Bay.

The orcas attacked the world’s biggest animal with their typical combination of strategy and ruthless persistence, until it either bled out or suffocated — or both.

John Totterdell has been studying orcas for years, but he had never seen anything like it.

As far as he knows — no one has.

Mr Totterdell, from CETREC WA, said there had only been a handful of blue whale predations documented by researchers.

The first, off the coast of California in 1979, involved a sub-adult whale measuring about 20m long.

But he said that whale was still alive when the observation ended.

In 2003, a blue whale calf was attacked and killed near the Costa Rica Dome. In May 2017 off California, drone footage showed orcas striking a blue whale before it fled to safety.

It is believed Thursday’s predation was the first documented killing of a sub-adult blue whale by orcas. Mr Totterdell said his crew had been on its way out to its usual depth when they stumbled across the encounter.

He said the scale of the attack, combined with the stormy weather and low visibility, made for an “ominous” scene.

“It was like doomsday out there and it was certainly doomsday for this blue whale,” he said.

Mr Totterdell said one of the biggest differences between Thursday’s predation and other attacks on smaller whales was that the big male orcas got involved. “The social structure of these animals is matriarchal. (The males) look big and powerful but often it’s for show,” he said.

“They seem a bit useless sometimes but on Thursday they were throwing their weight around.”

From the time Mr Totterdell arrived, the blue whale managed to survive the onslaught for about an hour. The crew left six hours later because the wind had picked up to almost 50km/h. The orcas were still feeding on the whale.

“The blue whales aren’t recovering as well as the humpbacks so from that point of view it’s a loss,” Mr Totterdell said.

“But wow — the sheer power these animals have and the teamwork. It’s incredible.”