In the vast expanse of the Northeastern Pacific Ocean, a mysterious population of killer whales roams the open waters, leaving researchers intrigued and astounded by their unique behaviors and characteristics. With cookie-cutter shark scars adorning their sleek bodies, these enigmatic orcas have captured the attention of scientists from the University of British Columbia (UBC), sparking a quest to unravel the secrets of this newfound population.
In a recent study published in Aquatic Mammals, UBC researchers shed light on the existence of a potential new subpopulation of killer whales inhabiting the waters off the coast of California and Oregon. Led by master’s student Josh McInnes and Dr. Andrew Trites, the team meticulously analyzed nine encounters spanning from 1997 to 2021, piecing together evidence that hints at the presence of a distinct group of orcas with behaviors and characteristics unlike any previously documented.
The journey to uncovering the identity of these elusive orcas began with observations of their predatory habits, which included hunting marine mammals such as sperm whales, pygmy sperm whales, northern elephant seals, and Risso’s dolphins. Perhaps most astonishing was their unprecedented attack on a herd of nine adult female sperm whales, marking the first known instance of killer whales preying on sperm whales in the region. These encounters provided researchers with invaluable insights into the feeding behavior and ecological niche of this mysterious population.
A key clue to the identity and habitat range of these orcas lies in the distinctive cookie-cutter shark bite scars found on almost all individuals. These parasitic sharks inhabit the open ocean, suggesting that the new population primarily dwells in deep waters far from the coast. Additionally, the orcas exhibit physical differences in their dorsal fins and saddle patches compared to the three main ecotypes—residents, transients, and offshores—found along the coasts of California and Oregon.
While the sizes and shapes of their dorsal fins and saddle patches bear resemblances to existing ecotypes, variations in fin shape and saddle patch patterns set them apart. Some orcas display pointed dorsal fins akin to transients, while others possess rounded fins reminiscent of offshores. Similarly, their saddle patch patterns vary, with some featuring large uniformly gray patches and others sporting smooth narrow patches more commonly seen in tropical killer whale populations.
Despite the absence of definitive matches with known killer whale populations through photos or descriptions, the researchers remain steadfast in their pursuit of understanding this newfound group. Citizen scientists, including fishermen and passengers on open-ocean expeditions, have played a crucial role in documenting sightings and providing valuable observations of the unidentified orcas.
The researchers aim to expand their dataset by documenting more sightings and gathering additional information, including acoustic data and genetic samples. These efforts will provide further insights into the behavior, ecology, and genetic distinctiveness of the shark-bitten orcas, shedding light on their role within the complex marine ecosystem of the Northeastern Pacific.
As the quest to unravel the mysteries of these elusive predators continues, one thing remains clear: the discovery of a potential new population of killer whales serves as a poignant reminder of the vastness and diversity of life that thrives beneath the surface of our oceans.
