LifestyleNew Discovery: Shark-Bitten Orcas Found in the Northeastern Pacific may be a...

New Discovery: Shark-Bitten Orcas Found in the Northeastern Pacific may be a New Population of Killer Whales

Research conducted by the University of British Columbia (UBC) suggests that a group of killer whales spotted hunting marine mammals, including sperm whales and a sea turtle, in the open ocean off the coasts of California and Oregon may represent a new and distinct population.

The findings, detailed in a recent publication in Aquatic Mammals, propose that the 49 orcas observed could either be a subgroup of transient killer whales or a unique oceanic population specifically located in the waters of California and Oregon.

According to Josh McInnes, a graduate student at the UBC Institute for the Oceans and Fisheries (IOF), “Observing killer whales in the open ocean is a rare occurrence, given that it is the largest habitat on Earth. This study sheds light on the movements and behaviors of killer whales in this environment, showcasing the differences from those inhabiting coastal regions.”

Exploring Ecotypes of Killer Whales

Currently, there are three recognized ecotypes of killer whales in the California and Oregon coastal areas: ‘residents’, ‘transients’, and ‘offshores’.

Although the unidentified killer whales have been sighted previously, the recent study presents a comprehensive analysis based on data collected from nine encounters involving 49 individuals between 1997 and 2021, providing a substantial foundation for the identification of a potential new population.

Dr. Andrew Trites, a professor at IOF and co-author of the study, stated, “Discovering a new population of killer whales is a significant achievement that requires extensive documentation and observation to distinguish unique characteristics of these animals.”

During the encounters with the orcas, researchers observed various remarkable behaviors, such as engaging with a group of adult female sperm whales, preying on a pygmy sperm whale, a northern elephant seal, and a Risso’s dolphin, as well as showing signs of feeding after scavenging a leatherback turtle.

Distinctive Characteristics and Habitats

The distinguishing feature of almost all the orcas in this new population is the presence of cookiecutter shark bite scars, indicating a potential habitat range primarily in deep waters far from the coast, where this parasitic shark is commonly found.

In addition to the bite scars, physical differences such as variations in dorsal fins and saddle patches were noted among these orcas. McInnes explained, “While the sizes of their dorsal fins and saddle patches resemble those of transient and offshore ecotypes, the shapes vary from pointed to rounded fins, and distinct pattern differences in their saddle patches were observed, akin to killer whales in tropical regions.”

In conjunction with ongoing marine mammal stock assessments, the identification of this unique killer whale population raises new questions and insights into the biodiversity and behavior of these magnificent marine predators.

For more information on this study, you can visit the following link: Read More

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