Researchers at the University of British Columbia say they have identified a potential new population of pelagic killer whales that hunt the largest predators on the planet.
In a study published Friday, researchers said a pod of 49 orcas was observed hunting sperm whales off the coast of California and Oregon.
Lead author Josh McInnes said the killer whale was seen hunting a pod of nine adult sperm whales and “eventually escaped with one”.
This is the first time an orca has been reported to have attacked a sperm whale on the West Coast.
“Other encounters have included attacks on pygmy sperm whales, predation on northern elephant seals and red pilot whales, and what appears to be a postprandial lull after scavenging for a leatherback turtle,” said the UBC master’s student. Mr McInnes said. Marine Fisheries Research Institute.
Researchers said the killer whales observed in nine encounters between 1997 and 2021 may belong to a transient killer whale subpopulation or an ocean-specific population.
According to the study, the last sighted encounter with a sperm whale occurred in 1997 about 80 miles off the coast of California. Many of the sperm whales in the pod suffered “severe injuries” and one died, the study said.
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“Initially about 12 orcas participated in the hunt, but their numbers have increased to an estimated 35 spread over a 3km area. randomly targeted and attacked sperm whales,” the study said, describing how the whales gathered in a circle with their heads close together and their tails facing outward.
“Fresh blood and oil slicks of animal fat were seen on the surface after each attack,” the study continued.
One of the whales was pulled from the rosette and several killer whales were seen feeding on it.
In another encounter in 2001, about 350 kilometers off the coast of California, seven orcas from the same group were observed foraging from a leatherback turtle.
McInnes said scientists collected many photos and data throughout these encounters, but none of the killer whales matched or were recognizable to any other killer whales known from the Northeast Pacific Ocean.
He points out that there are three different types of killer whales that live along the California and Oregon coasts: resident, transient, and offshore.
The individuals they encountered shared physical similarities with both the ephemeral and offshore ecotypes, but were not a “perfect fit” to either, according to the study. That’s what it means.
The report said there were also bite scars on the animal’s body from the cookiecutter shark, a type of parasitic shark that lives in the deep sea, allowing researchers to identify killer whales as possibly a new group.
“The presence of scars on cutter sharks provides indirect evidence that these unknown killer whales were spending time in warm waters,” the study said.
McInnes said nearly all of the orcas had scars, while others did not.
“But the big question is, what role do these killer whales play? We don’t know…but what we do know is that they spend more time in the open ocean. It’s representative of the population that you would expect to spend time with,” McInnes said in an interview.
Co-author Andrew Treitz of the UBC Institute of Marine Affairs and Fisheries said that given the time required to collect photos and recognize that the animals are distinct from known populations, new populations of killer whales are unlikely to emerge. He said the discovery was “very unique.”
The researchers said they also observed physical differences in killer whales, such as spots on their fins and saddles.
They said they want to record more sightings and data from the new population to investigate exactly how these killer whales differ from other recorded populations.
Mr McInnes said this discovery was the first part of a fun puzzle they were working on.
“We’re just at the tip of the iceberg of what these whales are doing. I mean, are they all the same population? Are there more than one? We don’t know. So this is us “We feel like it’s kind of a big start to the next step in our research, where we’ll probably get more sightings and more information,” McInnes said.
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