Great White Sharks Don't Always Flee After Orca Attacks, New Study Reveals

Australia - Ekhbary News Agency

Challenging the Narrative: Great White Sharks' Response to Orca Encounters Re-examined

The great white shark (Carcharodon carcharias), a creature often relegated to the realm of marine nightmares, is frequently perceived as an apex predator. However, its position at the top of the food chain is not absolute. These formidable hunters can themselves become prey to an even higher predator: the orca (Orcinus orca), also known as the killer whale. For decades, scientific understanding has suggested that orcas are the primary, if not sole, natural predator capable of killing a great white shark.

This predator-prey dynamic gained significant public attention in 2015 when tourists on a cage-diving boat near Australia's Neptune Islands witnessed a group of orcas apparently kill a great white. Following this dramatic event, great white sharks disappeared from the region for approximately two months. This observation, along with similar incidents reported in South Africa, led many to conclude that the presence or predation by killer whales was the definitive cause for such disappearances. Researchers hypothesized that these encounters trigger a strong flight response, causing sharks to abandon traditional feeding or aggregation sites for extended periods, sometimes weeks or months.

Dr. Charlie Huveneers, director of the Flinders University Marine and Coastal Research Consortium in Australia, previously noted the widespread observation of this phenomenon. "The sudden disappearance of white sharks following killer whale predation, or even presence, has been observed across different locations, including in South Africa or California," he stated. This established theory suggested a clear cause-and-effect: orca sighting equals great white vanishing act.

However, a groundbreaking study published in the journal *Wildlife Research*, co-authored by Dr. Huveneers, is now challenging this long-standing assumption. The research team employed a novel approach, analyzing over a decade's worth of acoustic tracking data combined with tourism sighting records. This extensive dataset, spanning multiple years, provided a more comprehensive picture than earlier studies that often relied on more limited observational data.

"Our research shows that long absences can happen naturally, even without killer whales present," Dr. Huveneers explained. "Across 12 years, we recorded six long absences, and only one coincided with killer whales." This finding is crucial, suggesting that the absence of great white sharks from certain areas might not always be a direct consequence of orca activity.

The study's implications extend further, demonstrating that "killer whales aren’t always, or the only, driver of long white shark absences." This means the widely cited 2015 Neptune Islands disappearance, where sharks vanished for two months after an apparent orca attack, might not have been solely triggered by the predation event. It's possible that natural factors were at play, or perhaps the sharks would have left the area around that time regardless.

Furthermore, the research indicates that the most significant shark absences recorded in their study period occurred without any known killer whale presence. In fact, the study suggests that direct killer whale predation or even just their presence might lead to shorter-term disappearances, rather than the prolonged absences previously theorized. This implies that the sharks' reaction to orcas might be more nuanced than a simple, extended flight response.

Dr. Huveneers also pointed out that other factors can influence shark movements, leading to temporary departures. These include shared environmental cues, such as changes in water temperature or currents, and chemical signals like necromones – compounds released by a dying shark that can alert others to danger or a potential food source, potentially influencing their dispersal.

Lauren Meyer, a marine scientist at Flinders University and co-author of the paper, emphasized the study's contribution: "This study highlights the importance of long-term monitoring to understand white shark movements and site fidelity, while challenging the idea that killer whales are always or solely responsible for prolonged shark absences."

The takeaway message is that while the predatory relationship between orcas and great white sharks is undeniable and fascinating, the reasons behind great white shark disappearances are more complex than previously understood. These magnificent predators may simply be exhibiting natural behaviors, responding to environmental shifts, or following their own migratory patterns, independent of the presence of killer whales. This research underscores the need for continued, long-term ecological studies to unravel the intricate behaviors and ecological interactions within our oceans.

Ekhbary News Agency