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Killer whales seen with shark bites may be a completely new population

Researchers believe they have identified a new population of killer whales, a revelation that highlights the rich and largely unexplored biodiversity of our planet’s largest habitat.

This potential new group of 49 orcas has been observed off the coasts of California and Oregon engaging in unique hunting behaviors, targeting marine mammals such as sperm whales and even a sea turtle.

The study from University of British Columbia (UBC), published in the journal Aquatic Mammals, presents compelling evidence that these orcas may either form a subpopulation of transient killer whales or constitute an entirely new oceanic population.

Hidden giants: A new orca population discovered

Josh McInnes, a master’s student at the UBC Institute for the Oceans and Fisheries (IOF) and the study’s first author, emphasizes the rarity of such observations in the open sea.

“The open ocean is the largest habitat on our planet, and observations of killer whales in the high seas are rare. In this case, we’re beginning to get a sense of killer whale movements in the open ocean and how their ecology and behavior differs from populations inhabiting coastal areas,” explained McInnes.

Typically, three ecotypes of killer whale are found along the coasts of California and Oregon: residents, transients, and offshores. The newly observed orcas, documented through nine encounters from 1997 to 2021, could not be matched with any known animals, sparking the hypothesis of a new population.

Dr. Andrew Trites, a professor at the IOF and co-author of the study, notes the significance of such a find, stating, “It’s pretty unique to find a new population. It takes a long time to gather photos and observations to recognize that there’s something different about these killer whales.”

Deciphering the behavior of this killer whale population

One of the most striking behaviors observed was the group’s hunting tactics. In one encounter, researchers witnessed the pod attacking a herd of nine adult female sperm whales, a behavior not previously reported on the west coast.

Other encounters included attacks on a pygmy sperm whale, a northern elephant seal, Risso’s dolphin, and a leatherback turtle.

A distinctive clue to this new population’s habitat comes from the cookiecutter shark bite scars observed on almost all of the orcas. This detail suggests that the killer whales primarily inhabit deep waters far from land, as cookiecutter sharks are known to live in the open ocean.

Unique traits help identify new orcas

Furthermore, the orcas exhibit physical characteristics that set them apart from the known ecotypes. Their dorsal fins and saddle patches (the grey or white patches by the fin) show variations that hint at a genetic distinction.

“While the sizes and shapes of the dorsal fins and saddle patches are similar to transient and offshore ecotypes, the shape of their fins varied, from pointed like transients to rounded like offshore killer whales,” McInnes elaborated.

“Their saddle patch patterns also differed, with some displaying large uniformly grey saddle patches and others having smooth narrow saddle patches similar to those seen in killer whales in tropical regions,” he concluded.

Contributions from citizen scientists

The discovery has sparked interest among the maritime community, including fishermen and passengers on whale-watching tours, some of whom have taken up photographing these orcas as a hobby.

Dr. Trites highlights the collaborative nature of this research, with sightings and data provided by those who spend significant time at sea.

Moving forward, the researchers aim to document more sightings and gather additional data, including acoustic recordings of the orcas’ calls and genetic samples, to further explore how this potential new population may differ from or align with already documented killer whale populations.

Future studies of this killer whale population

In summary, the discovery of a potential new population of killer whales marks a significant leap forward in our understanding of the complexities of marine life.

By combining rigorous scientific research with observations from the maritime community, researchers have revealed the unique behaviors and characteristics of these enigmatic creatures, underscoring the vast, unexplored wonders of the ocean.

This study enriches our knowledge of killer whale populations and emphasizes the critical need for continued exploration and conservation efforts in our planet’s largest and most mysterious habitat.

As we move forward, the ongoing study of these orcas promises to reveal more about their lives, offering insights into the intricate balance of marine ecosystems and the vital role these apex predators play within them.

The full study was published in the journal Aquatic Mammals.


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