More Than 50 Orcas Hunt and Kill Blue Whale Off Australian Coast

This is one of just a handful of times that orcas have ever been recorded killing a blue whale

killer whales
As many as 70 orcas cooperatively hunted, killed and ate a roughly 50-foot long blue whale last month off the coast of Australia. Naturaliste Charters

Last month, a group of between 50 and 70 orcas hunted and killed a blue whale off the southern coast of Western Australia, report John Dobson and Toby Hussey for the Australian Broadcasting Corporation (ABC).

A boat full of stunned whale watchers witnessed the more-than-three-hour attack on the blue whale on March 16 in an area known at Bremer Bay Canyon, wrote marine biologist Kristy Brown in a blog post for the whale watching boat operator Naturaliste Charters.

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The roughly 50-foot-long victim may have been a juvenile blue whale (Balaenoptera musculus) or an adult pygmy blue whale (Balaenoptera musculus brevicauda), since both are known to pass through the area where the attack took place and are similar in size and appearance, Brown tells Laura Geggel of Live Science via email. Whatever the species, the blue whale dwarfed its attackers. Male orcas can reach a maximum size of roughly 30 feet in length and have also been known to attack and kill gray whales, humpback whales, sea lions and even great white sharks.

This attack is one of just a handful of times that orcas or killer whales have been seen taking down a blue whale. Naturaliste Charters has recorded orcas killing a blue whale on two other occasions, Brown tells Live Science. "Both of these were in April 2019, and were two weeks apart," says Charters.

The boat wasn’t able to operate during the 2020 blue whale migration season due to Covid-19 “so we were not at sea at the time when the blue whales were migrating north from Antarctica (mid-March, April, May), therefore we do not know if the same dynamic occurred last year," Brown adds.

Cathy Finch, a writer lucky enough to be aboard the ship during the rare phenomenon, reports for Australian Geographic that during the first two hours of the encounter groups of six to eight orcas would take turns pushing, bumping and ramming their quarry in attempts to drown the krill-feeding baleen whale while also herding it into shallower water so that it’s carcass couldn’t sink too deep for the predators to feed. When each group of orcas wore themselves out bullying the big blue with breaches and tail slaps at the surface, they would tag in a fresh band of killers and wait off in the margins while they regained their strength.

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Per Australian Geographic, the orcas, which are actually the largest members of the dolphin family, finally drew blood after around three hours of battering the blue whale. Evidently, the black and white hunters began by biting and ripping at their prey’s soft, massive tongue.

At this point the commotion had attracted a bevy of marine onlookers, including seabirds, a group of long-finned pilot whales and a hammerhead shark, each hoping to snag a piece of food for themselves, according to Brown’s blog.

Per the blog post, the blue whale met its end around 3 p.m. local time after what she called a “gallant” fight. “A bubble of blood rose to the surface like a bursting red balloon,” Brown wrote.

As for the people aboard the whale watching boat, Brown wrote “some patrons were in tears, some stunned silence, some excited and intrigued."

Finch observed up to eight adult male orcas were in the area with their pods. Once the kill had been made, the groups divided up hunks of flesh and blubber from the slain blue whale to bring back to the rest of the group.

Reflecting on the incident, Brown writes that she and the others on the boat that day were “witnesses to one of the greatest natural phenomena imaginable. This was a glimpse into the life of the ocean’s apex predators.”