The killer whale (Ornicus orca) is the species presented on many occasions as a model of super predator, that is, the predator that has no natural predators, placing itself at the top of its food chain. The ability of orcas to attack has been proven and filmed on numerous occasions in various seas and oceans, but in almost all known cases, the hunting strategy for prey of large size or defense capacity (such as sharks or whales) consists in coordinated group attacks.
The episodes of shark hunting carried out in recent years by groups of orcas off the coast of South Africa are an example of the description of super predator to the point of surprising even experts. The actions of the killer whales are so remarkable that they have caused a migration of white sharks to other waters, as demonstrated in a study published (2022) in the African Journal of Marine Science. This type of action would have started in this area approximately in 2017, according to the authors of the study.
A scientific team led by Professor Alison Towner (Rhodes University and Dyer Island Conservation Trust), the same researcher who demonstrated the first group attacks by killer whales on white sharks in South Africa in 2022, now also presents in the African Journal of Marine Science (March 2, 2024) - the first known case of a single, fatal attack by an orca on a white shark.
"This astonishing predation, observed off the coast of Mossel Bay, South Africa, represents unprecedented behavior that underlines the exceptional ability of the orca," said Professor Alison Towner in statements released by Rhodes University.
Orcas are generally known to work together to capture large prey such as sea lions, seals and even other whales and of course sharks as well. When hunting together, they can surround their prey and use their combined intelligence and strength to attack.
They can hunt large animals individually. However, this is the first time something like this has happened in one of the world's largest predators: the great white shark (Carcharodon carcharias).
"Once again, as before in South Africa, killer whales show a strong preference for extracting and consuming the lipid-rich livers of white sharks, a specialized feeding behavior," explains Towner, who has studied great white sharks for the past 17 years. years; detailing their movement patterns through data that includes knowledge of individual specimens.
“In this case, what we witnessed was an orca, nicknamed Starboard, recognizable by its dorsal fin deflected to one side, acting alone to kill and consume a great white shark in an action that was astonishingly completed in just two minutes. The prey was a juvenile shark 2.5 meters long. "The orca extracted and devoured the shark's liver shortly after killing it," explains the lead author of the study.
"This sighting revealed evidence of solitary hunting by at least one orca, challenging conventional cooperative hunting behaviors known in the region.
"These are groundbreaking insights into the predatory behavior of this species, and our findings contribute significantly to the global understanding of killer whale predation dynamics, improving knowledge of marine ecosystems and predator-prey relationships."
During the observed interactions of this event, at least two great white sharks died, as evidenced by the discovery of a second carcass measuring 3.55 meters nearby.
"The study raises critical questions about the impact of killer whale predation on shark populations in South Africa," says Towner. "The displacement of several shark species due to the presence of killer whales may have implications for the release of mesopredators [mid-range predator] and possible trophic changes in the marine ecosystem."
Understanding the ecological dynamics of killer whale predation is critical to marine conservation efforts. The authors state that this event "underscores the urgent need for adaptive conservation strategies and vigilant ecological monitoring amid changing environmental conditions."
Study co-author Primo Micarelli, from the Center for Shark Studies and the University of Siena, was aboard the White Shark Africa vessel from which the monitoring was being carried out and commented: "During two decades of annual visits to South Africa, I have "We've seen the profound impact these orcas have. Watching Starboard carry the liver of a great white shark past our boat is unforgettable."
