Rogue orcas are thriving on the high seas—and they’re eating big whales
A fourth type of Pacific killer whale may live miles offshore from California and Oregon, preying on whales, other dolphins, and sea turtles.
By Melanie Haiken
Most orcas tend to stick to coastlines, from the Antarctic dwellers that make waves to knock seals off ice floes to the liver-extracting brothers around Cape Town. But now, scientists have found what could be a brand-new population of killer whales: Animals that ply the high seas, hunting large whales and other sizable prey.
These open-ocean denizens have been spotted at numerous locations far from Oregon and California, many of them well beyond the continental shelf, where waters can reach depths of 15,000 feet, according to a recent study in Aquatic Mammals.
“There haven’t been any real studies, at least in the North Pacific, looking at killer whales in the open ocean,” says study leader Josh McInnes, a master’s candidate at the University of British Columbia’s Institute for the Oceans and Fisheries.
It was kind of a shock when … we saw animals that were out in this open ocean habitat and were completely different from the other ecotypes we know.
Killer whales in the Pacific are grouped into three ecotypes: Residents, which live close to shore and eat salmon and other fish; offshores, which live farther out and also eat fish; and transients, also called Bigg’s, the only orcas previously known to eat mammals. (See 13 fantastic photos of orcas.)
Scientists could not match the 49 whales in the new study with any known orcas through photos and descriptions, which are based on their unique dorsal fins and saddle patches, the gray or white pattern on an orca’s back.
This means the animals are either a subgroup of the transient ecotype or an entirely unique population, says McInnes, who is also a research associate with the Pacific Wildlife Foundation.
The team could also differentiate the population, dubbed the oceanics, from other known orcas due to scars or bite marks from the parasitic cookie-cutter shark, which only occur in the deep ocean.
Beyond individual variations, the oceanics don’t look like other known ecotypes, for example sporting a large gray saddle patch or no saddle patch at all.
“The open ocean doesn’t support a lot of large predators; it’s often described as a giant desert, so we weren’t expecting to find so many different animals, so we’re excited to carry on more research,” McInnes says.
“We really just don’t know yet what is happening with the killer whales in the open ocean. This is the mystery behind what we hope to do next.”
Following the prey
Our knowledge of orcas living in the open ocean is limited, as it’s difficult to find the widely distributed animals in a boat.
Yet the recent paper, a mixture of literature review and new observations, discovered nine instances in which marine mammal researchers, fishermen, and tourists observed whales in the northern Pacific Ocean between 1997 and 2021.
In the first documented incident, researchers watched a large pod of killer whales attack a herd of nine adult female sperm whales, managing to separate one from the pack and kill it. Other pods also hunted and ate an elephant seal, a pygmy sperm whale, a Risso’s dolphin, and a leatherback sea turtle.
With detailed records from each such encounter, the researchers plotted geo-referenced locations, determined water depth, and compared photos in databases to determine that the 49 whales sighted could potentially be a new ecotype.
It’s possible that this new population formed as prey drew them farther from shore.
“Mammal-eating killer whales are doing well, and their numbers are increasing as seal and other whale populations have rebounded since whaling and sealing became illegal,” says Robert Pitman, a marine ecologist at Oregon State University’s Marine Mammal Institute, who wasn’t involved in the study.
While prey overall is less abundant in deep-sea waters, killer whales may still find that habitat is more appealing than competing with the larger populations of resident whales closer to shore, he says. (Watch video: sperm whales vs. orcas.)
To this end, McInnes and colleagues hope this study will spark efforts to document the new whale population through genetic sampling, satellite tagging, acoustic tracking, further photo identification, and additional field observation.
Team Orca
Climate change is affecting some populations of killer whales, such as those in Antarctica, which depend on seals that live on the rapidly decreasing ice. On the U.S. West Coast, a decline in salmon has reduced a population off Puget Sound, Washington.
Worldwide, however, the species is thriving, and coming more into contact with people in coastal areas. Orcas ramming and even sinking boats off Spain made headlines in 2023, with some people rooting for the animals as fighting back against human domination.
“Killer whales are probably the most widely distributed vertebrate on the planet. They are everywhere,” Pitman says.
With many tourist cruises available worldwide, he encourages everyone to put seeing a killer whale, whose males can reach lengths of 27 feet, on their bucket list.
“This is the biggest apex predator we have on the planet today. We haven’t seen anything like it since dinosaurs roamed the Earth.”
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Killer whales deploy brutal, co-ordinated attacks when hunting
Their techniques are passed down through the generations
The killer whales that roam the waters of the Monterey Submarine Canyon, off the coast of California, are brutal animals. When hunting grey whales, they target mother and calf pairs, chasing them until the calves begin to tire. At that point the killer whales separate the grey whales by manoeuvring between them or dragging the calves away by their tail flukes or fins. Once a calf is separated from its mother, the killer whales incapacitate it by bludgeoning it with their heads and tails before drowning it by leaping atop its blowhole to keep it below the surface.
The killer whale (Orcinus orca) is a diverse species, boasting several isolated populations around the world that occupy varying—and, in several cases, still little described—ecological niches. Two recent studies have shed some light on the unique hunting cultures of the killer whales that stalk the deep waters off the north-east Pacific Ocean.
Distinct killer whale populations are known as “ecotypes” and can differ in size, colour and body proportion. Where their ecological ranges overlap, ecotypes rarely interact and do not appear to interbreed. Most of what makes killer-whale ecotypes distinct is their culture—socially learned behaviours that killer whales are known to transmit from one generation to the next. These include preferences for different marine prey species and the collaborative strategies used to locate, hunt and kill them, potentially honed over millennia. Different killer-whale ecotypes even communicate using distinct “dialects” made of clicks, whistles and calls, with “accents” that differ between pods.
The most studied killer-whale ecotypes are the three that occupy the north-east Pacific coastline, from northern Alaska to southern California. “Offshore” killer whales, up to 6.6 metres long, patrol distant waters in pods of 100 to 200 individuals, hunting pelagic fishes like sharks. “Resident” killer whales, around 7 metres in length, stalk the coastline in pods of up to 25 individuals, targeting coastal fishes (primarily salmon). Finally, “transient” killer whales, each up to 8 metres in length, are found across both shallow and deep coastal waters and pursue marine mammals, including cetaceans (whales and dolphins), as well as pinnipeds (sea lions and seals). While “inner-coast” transients stalk shallow waters near the shore, “outer-coast” transients hunt in the deep open waters along canyons at the edge of the continental shelf.
To understand these transient killer whales better, Josh McInnes from the University of British Columbia in Canada led a team that analysed 261 sightings of killer whales around the Monterey Submarine Canyon System collected by surveys and whale-watching vessels. The dataset included almost 100 predation events. Publishing their results in the journal plos one, Mr McInnes found patterns in behaviour of outer-coast transients that differed from those of their inner-coast cousins. The latter ambushed harbour seals, sea lions and the occasional otter, while the former tended to perform co-ordinated dives in their hunt for larger mammalian prey.
(Cetacean needed)
Outer-coast transients appear to have developed specialised strategies—such as the repeated battering and drowning of grey whale calves—because their prey is bigger and takes more time to subdue. Like most specialised killer-whale hunting behaviours, these strategies are thought to be honed, down the generations, as a form of cultural knowledge.
While studying the outer-coast transients, Mr McInnes also stumbled upon hints of a previously undescribed population of killer whales that were big-game hunters of an entirely different class. Writing in the journal Aquatic Mammals, his team described nine offshore encounters with 49 killer whales between 1997 and 2021. These killer whales were seen killing sperm whales, pygmy sperm whales and large Risso’s dolphins, as well as scavenging on leatherback turtles.
The attack on sperm whales, which can grow to around ten times larger than adult killer whales, was a particularly impressive show of predatory force. On October 21st 1997, between 15 and 35 killer whales were observed hunting a herd of nine sperm whales over the course of four hours. The sperm whales were subjected to repeated waves of aggressive attack, injuring all of them and severely injuring several before one sperm whale was finally isolated from the herd and killed. Out of the surviving sperm whales, three are thought to have died from the wounds they sustained and it is possible the entire herd later succumbed to its injuries.
Little more than that is known about these killer whales for now, except that they are identifiable by characteristic circular scars left by bites from cookie-cutter sharks, which suggest these hyper-aggressive creatures stalk the deep waters of the north Pacific.
More data, especially of the genetic kind, will need to be collected from both outer-coast transient killer whales as well as their newly discovered cousins terrorising the pelagic waters of the north Pacific, before scientists can fully describe the new ecotypes and add them to marine-biology textbooks. Nevertheless, the discoveries are a reminder that biodiversity is not just about the diversity between species but also within them. Killer whales seem to exist in many more shades than just black and white. ■
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Vengeance—or playtime? Why orcas are coordinating attacks against sailboats
The common denominator in dozens of incidents appears to be a mature female named White Gladis.
Orcas, or killer whales, are well known for their intelligence and for their remarkable hunting techniques: whether it’s turning great white sharks upside down or working cooperatively to take down large whales. And a population of orcas off the Iberian Peninsula has been gaining attention over the last three years—and causing angst among sailors—by attacking and even sinking boats in the area.
The first recorded attack occurred in the Strait of Gibraltar in May 2020, with dozens of cases recorded since then. Most of the incidents are remarkably consistent, generally involving a small group of whales attacking the rudders of small sailboats before breaking off and swimming away.
In June and November 2022, a pair of attacks caused two boats to sink; earlier this month, a badly damaged boat sank while it was being towed to shore.
Why the attacks may have started
A recent paper in the journal Marine Mammal Science found that the attacks involved nine whales in two groups: a trio, sometimes a quartet, of juveniles; and a mixed-age group led by a mature female named White Gladis. Given that White Gladis was the only mature female involved, the paper’s authors speculated that she had been involved in an accident with a boat and engaged in retributive behavior, which was then copied by the younger whales.
“When it started happening, I did think that maybe a female or her calf had been nicked by a propeller or rudder on a boat, because every single time they seem to go for the rudder. And it’s all on sailboats,” says Dan Olsen, a field biologist with the North Gulf Oceanic Society in Alaska.
However, not everyone is convinced that the orcas’ actions have any malevolent intent. Notably, the orcas’ focus is very specifically on the boats; none have shown any interest in the people on board, even when those people have had to scramble into lifeboats when their vessels started sinking.
“I think it’s just as reasonable to suggest that they’re doing this because they can, because it’s fun,” says Hanne Strager, co-founder of the Andenes Whale Center in Norway and author of the recently published book The Killer Whale Journals.
A new form of play
Strager spoke to a biologist who was on board the boat that sunk in November, “and he said, ‘We didn’t feel any aggression.’ And, to me, that’s actually a strong testimony. Because I think when you are interacting regularly with animals, and you’re used to reading them, you can feel an aggressive intent, and they didn’t.”
If the orcas are indeed playing, it may suggest that, in time, the boat attacks could end when the whales get bored. Orca populations around the world have been observed engaging in a new behavior for no obvious reason than that they appear to enjoy it and then, just as suddenly, dropping it and moving onto something else. Orca researchers call these play routines “fads.”
Olsen, for example, has observed killer whales off Alaska playing with a piece of kelp for an hour: dragging it around on their fins, dropping it, circling back around and then picking it up in their teeth and swimming around with it some more. Strager has observed similar behaviors in orcas off the coast of Norway.
“For a while we saw them playing around with jellyfish,” she says. “They would swim with them on their snouts and would try to keep them on for as long as possible.”
There’s no benefit from this behavior, and the orcas were not eating the jellyfish, Strager notes.
“Sometimes we also see them whack little auks … small Arctic birds, they just lie on the surface of the sea to rest, and the orcas will come and whack them,” which she thinks is also a form of play.
Olsen questions whether we will ever truly understand the motivation behind the behavior, or whether we even really have the capacity to figure it out.
“The whale brain has been evolving separately for 50 million years,” Olsen says. “It’s hard to get a whale into an MRI, we don’t even know which parts of the brain are dedicated to which activity. It’s hard enough for us to explain behavior in humans and in primates that are closely related to us.”
Facing retaliation
Only this population has shown any interest in attacking boats, and it is a small one: the Marine Mammal Science paper cited an estimate of just 39 individuals.
The population in this region is under threat, says Strager, from tuna fishing, pollution, noise and, indeed, ship strikes.
“They are among the most polluted marine mammals in the world, so their breeding success is not good. It’s a very stressful environment for them,” she says.
And now, added to the existing stressors is the prospect of retaliation.
“Now they are becoming feared in the area,” notes Strager, “and there are reports of people suggesting you should pour diesel on top of them if they attack your boat, that you should put firecrackers in the water or ignite dynamite. I understand if people are afraid. But it’s really a very dangerous situation for the killer whales.”
One local group, the Atlantic Orca Working Group, catalogues interactions between whales and boats so that sailors can learn which areas to avoid.
