Researchers at the University of British Columbia believe there may be a new population of killer whales, a group of killer whales that prey on marine mammals, including sperm whales, and sea turtles in the open ocean off California and Oregon. Based on existing evidence, researchers in a new study published Aquatic MammalsHe notes that the 49 killer whales may belong to a subpopulation of transient killer whales or a unique oceanic population found in waters off the coasts of California and Oregon.

“The open ocean is the largest habitat on our planet, and offshore killer whale sightings are rare,” said first author Josh McInnes, a graduate student at UBC’s Institute of Oceans and Fisheries (IOF). “In this case, we are beginning to gain insight into the movements of killer whales in the open ocean and how their ecology and behavior differ from populations living in coastal areas.”

Three orca ecotypes inhabit the coasts of California and Oregon: “resident,” “transient,” and “pelagic.”

Unique behavior and features

Researchers say unknown killer whales have been spotted before, but the new paper contains enough rich evidence from nine encounters with 49 animals between 1997 and 2021 to form a solid hypothesis.

“Finding a new population is quite a unique thing. It takes a long time to collect photographs and observations to understand that there is something different about these killer whales,” says co-author IOF professor Dr. Andrew Traits.

49 killer whales, with photos and descriptions, cannot be compared with any other known animal. “The researchers’ first encounter with a pod of these oceanic killer whales saw them fight a pod of nine adult female sperm whales and eventually escape with one. This is the first attack by killer whales on sperm whales on the West Coast,” McInnes said. “Other encounters include an attack on a pygmy sperm whale, predation on a northern elephant seal and Risso’s dolphin, and a post-prandial lull following the downing of a leatherback turtle.”

Shark tracks provide important clue

An important clue to the new population’s presumed habitat lies in the shark bite marks seen on nearly all killer whales. This parasitic shark lives in the open ocean; This means the new population lives mostly in deep waters away from land.

Killer whales also have physical differences between the three main ecotypes, including dorsal fins and saddle points (gray or white spots near the fin). “Although the sizes and shapes of the dorsal fins and saddles are similar to those of transitional and marine ecotypes, the shape of the fins varies from pointed, as in transitional whales, to rounded, as in marine killer whales,” McInnes said. said. “Some had large, uniform gray saddles, while others had smooth, narrow saddles similar to those seen on killer whales in the tropics.”

Ongoing research and community engagement

Dr Traits said that as well as studies to assess marine mammal populations, fishermen and travelers on open ocean bird watching and whale watching trips had also provided sightings of unidentified killer whales. According to the researchers, the discovery of the new population has become something of a hobby for fishermen; some of these purchased cameras for their travels specifically to film the encounter.

Researchers hope to document more sightings and collect more information about the killer whales’ calls, including acoustic data and genetic information from DNA samples, and to further investigate how these killer whales may differ from already documented populations.