New type of killer whale in the northeastern Pacific, identified by shark bites

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Researchers from the University of British Columbia (UBC) have stumbled upon a potentially new population of killer whales off the coast of California and Oregon.

This discovery, detailed in the journal Aquatic Mammals, sheds light on the complex lives of these majestic creatures in the open ocean, a region where sightings are rare and every encounter is precious.

The study, led by Josh McInnes, a master’s student at the UBC Institute for the Oceans and Fisheries (IOF), and co-authored by IOF professor Dr. Andrew Trites, is based on observations from nine encounters involving 49 orcas between 1997 and 2021.

These encounters have provided significant insights, suggesting that these killer whales could be either a subpopulation of transient killer whales or a unique oceanic population thriving in the waters far from the familiar coastal habitats.

Killer whales, or orcas, are known to inhabit various regions worldwide, and three distinct ecotypes are recognized along the California and Oregon coasts: ‘residents,’ ‘transients,’ and ‘offshores.’

However, the group McInnes and his team have been studying shows characteristics that don’t entirely match any of these known categories. This has led to speculation about the existence of a new population that has adapted to life in the vast expanses of the open ocean.

One of the most intriguing aspects of this potential new population is their diet and hunting behavior. In one of the documented encounters, the orcas were observed attacking a herd of sperm whales, a behavior not previously reported in these waters.

The encounters also included attacks on a pygmy sperm whale, a northern elephant seal, Risso’s dolphin, and even a leatherback turtle, showcasing the wide range of prey these orcas are capable of hunting.

Physical features and scars from encounters with cookie-cutter sharks have provided additional clues to these orcas’ lives. Almost all observed individuals bore marks from these parasitic sharks, which inhabit the open ocean, hinting at the orcas’ deep-water preferences.

Variations in the shapes of their dorsal fins and saddle patches further indicate that these killer whales may not fit neatly into the existing categories of resident, transient, or offshore orcas.

The discovery of this potential new population of killer whales highlights the vast, unexplored territories of the ocean and the creatures that inhabit them.

It opens up new avenues for research, including the collection of acoustic data to study their calls and the analysis of DNA samples to understand their genetic makeup better.

As the researchers continue to gather more information, the enthusiasm among fishermen and the public grows, with many now actively participating in documenting sightings of these elusive orcas.

This collaborative effort between scientists and the community could pave the way for a deeper understanding of killer whale populations and their adaptations to life in the open ocean, offering new perspectives on the biodiversity of our planet’s largest habitat.

The research findings can be found in Aquatic Mammals.

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