A specialized group of orcas, known as Moctezuma”s pod, has been observed in the Gulf of California methodically hunting young great white sharks. Recent footage shows these orcas employing a unique strategy: flipping the sharks upside-down to access their nutrient-rich liver.
This behavior may be a response to changing environmental conditions, as warming waters seem to be altering the habitats where juvenile sharks are nurtured. These younger sharks, lacking the survival skills of their elders, may be more vulnerable to orca predation.
“I believe that orcas that consume elasmobranchs, which include sharks and rays, would have the capability to hunt great white sharks anywhere they sought them,” stated marine biologist Erick Higuera Rivas, who leads the project at Conexiones Terramar and Pelagic Life. He is also the principal author of a study published in Frontiers in Marine Science.
The researchers documented two separate hunting events, during which three juvenile white sharks were killed. The hunts were meticulously recorded, allowing scientists to identify the individual orcas involved by examining their dorsal fins. In the first incident, which occurred in August 2020, five orcas chased a juvenile white shark to the surface, successfully flipping it over and ultimately re-surfacing with its liver.
A second hunt, observed in August 2022, followed a similar pattern. The orcas turned another juvenile shark onto its back, causing it to bleed from its gills while they consumed its liver.
This technique of turning a shark upside-down induces a phenomenon known as tonic immobility, which temporarily paralyzes the shark and makes it defenseless. “This state allows the orcas to extract the liver, which is rich in energy, as well as possibly other organs,” explained Higuera.
By examining the wounds on the sharks, scientists theorize that the orcas may have developed specific methods to achieve tonic immobility, thereby reducing the risk of being bitten. Smaller, less experienced juvenile great whites are likely easier targets.
“This marks the first instance of orcas consistently targeting juvenile white sharks,” remarked Dr. Salvador Jorgensen from California State University, a co-author of the study. “Adult white sharks tend to react swiftly to hunting orcas, vacating their seasonal gathering spots and often not returning for extended periods. Juvenile white sharks, on the other hand, may be unaware of the threat posed by orcas.” The research raises questions about whether the flight responses of white sharks are instinctual or learned behaviors.
Upon further investigation, the pod was confirmed to be Moctezuma”s pod, named for one of its notable members. This pod has previously been observed hunting rays and larger sharks like whale sharks and bull sharks, possibly gaining insights into effectively tackling great white sharks.
The shifting distribution patterns of white sharks in the Pacific could have presented new opportunities for Moctezuma”s pod. Climate phenomena such as El Niño appear to have altered the nursery areas for white sharks, leading to an increased presence in the Gulf of California. This change may make the juvenile sharks more susceptible to predation from orcas.
However, these findings are preliminary, and the researchers intend to conduct a more extensive survey to determine the dietary habits of this orca population. This follow-up will help clarify whether they regularly hunt white sharks or specifically target juveniles when they are present. Field studies are challenging due to high costs and the unpredictability of orca hunts.
“So far, our observations indicate that this pod primarily feeds on elasmobranchs,” noted Dr. Francesca Pancaldi from the Instituto Politécnico Nacional Centro Interdisciplinario de Ciencias Marinas and a co-author of the study. “There could be additional dietary preferences. Understanding the remarkable feeding behaviors of killer whales in this area will help identify their critical habitats, allowing for the establishment of protected zones and management plans to mitigate human impact.”
For further reading, see the study titled “Novel evidence of interaction between killer whales (Orcinus orca) and juvenile white sharks (Carcharodon carcharias) in the Gulf of California, Mexico,” published in Frontiers in Marine Science.
