The Battle for Apex Predator Status in South Africa’s Waters
In the waters off the coast of South Africa, a dramatic predator-prey juxtaposition is playing out. The long-held view of great white sharks as the ultimate apex predators is being challenged by the rise of a formidable pair of orcas known as Port and Starboard.
These two orcas have become notorious for targeting great white sharks, extracting their nutrient-rich livers with surgical precision. The implications of their behavior ripple far beyond the deaths of individual sharks, reshaping the marine ecosystem itself.
The Vanishing Great Whites of Gansbaai
Gansbaai, once celebrated as the “great white shark capital of the world,” has experienced a steep decline in shark sightings since 2017. This mysterious disappearance initially puzzled researchers, who suspected human activities such as overfishing.
However, evidence soon pointed to a more surprising culprit: orcas. Marine biologist Alison Towner noted the grim discovery in 2017 when “the bodies of white sharks began to wash ashore… each one with a unique injury”—their livers had been meticulously removed.
Subsequent studies confirmed the involvement of Port and Starboard. By 2022, researchers documented at least nine great whites washed ashore, their injuries unmistakably consistent with orca predation. This predation marks a shift in the balance of power, as orcas assert themselves over what were once thought to be untouchable ocean giants.
Orcas: The New Apex Predators
Port and Starboard’s hunting prowess extends beyond great whites. Reports reveal that the pair killed 17 broadnose sevengill sharks in a single day. After an orca attack, great white sharks exhibit a behavior known as “displacement,” vacating the area for extended periods—weeks or even months at a time. Towner described the phenomenon, saying, “Initially, following an Orca attack in Gansbaai, individual Great White Sharks did not appear for weeks or months.”
The effects of these disappearances cascade through the marine ecosystem. Without great whites to keep their populations in check, other species, such as copper sharks, are moving into the void left behind. This shift brings its own set of ecological challenges.
Ecological Consequences of Displacement
The decline of great whites in Gansbaai’s waters is not just a headline—it’s a catalyst for significant ecological change. The absence of these apex predators has allowed copper sharks, also known as bronze whalers, to proliferate in areas previously dominated by great whites. However, these new mesopredators are not safe from Port and Starboard either. As Towner explained, “It has triggered the emergence of a new mesopredator to the area… and these Bronze Whalers are also being attacked by the Orcas too.”
This domino effect—where one predator’s decline leads to shifts in the behavior and populations of other species—illustrates the fragile interconnectedness of marine ecosystems. The consequences of these changes could be long-lasting and unpredictable.
Why Shark Livers?
One of the most intriguing aspects of Port and Starboard’s hunting behavior is their focus on shark livers. Rich in fats and oils, these organs provide a highly concentrated source of nutrients, essential for orcas during their extensive migrations.
Towner described their coordinated strategy: “Two orcas take a pectoral fin in their mouth and pull open a shark together to extract the liver.” This precision suggests not only advanced hunting techniques but also a level of cultural knowledge passed between orcas.
What Comes Next?
The interactions between orcas and great white sharks in South Africa’s coastal waters offer a striking example of how predator behaviors can reshape entire ecosystems. Towner summed up the situation succinctly: “What we seem to be witnessing… is a large-scale avoidance strategy” among great whites due to the presence of orcas. This avoidance is just one piece of a larger puzzle, as scientists continue to explore the full impact of these interactions.
Ongoing research, enhanced tracking studies, and citizen science initiatives will be essential to understanding the long-term effects of these predator-prey dynamics. As the battle for apex status plays out beneath the waves, its outcomes will likely influence not only the future of these species but the broader health of marine ecosystems along South Africa’s coast.
Read Next:
- Get To Know The Orca – Killer Whale
- Get To Know The Great White Shark
- Where To Go Cage Diving With Sharks Near Cape Town