Great white sharks at risk of extinction due to this formidable predator

It's confirmed: the orca has targeted the great white sharks of Australia. A recent study, published in the scientific journal Ecology and Evolution, revealed a new phenomenon that could heavily impact the balance of the marine ecosystem.

It was by relying on numerous field observations and DNA analyses that researchers were able to confirm the behaviour of these formidable predators. As reported by GEO, a 4.7-metre great white shark washed up near Portland in October 2023, in the Australian state of Victoria. Strange fact: the animal's liver, as well as its digestive and reproductive organs, had disappeared. Some observers, two days before this discovery, noted the presence of orcas in this area, capturing a large prey. DNA samples on the bite marks were then collected by researchers, confirming the orca's DNA around a wound located near the shark's pectoral fin.

A first confirmed proof

The lead author of the study and researcher at Flinders University, Isabella Reeves, explains that this analysis is "the first confirmed proof - using DNA and observation data - of orca predation on great white sharks in Australia, and their selective consumption of the liver". According to her, orcas and great whites are “both super predators". She also notes that the analysed shark carcass had "four distinctive bite wounds". One of them clearly indicated that orcas had "deliberately ripped out the liver" of the shark. With regard to this predation phenomenon, Isabella Reeves reaffirms the importance of better understanding the dietary habits of orcas in order to evaluate their impact on the marine ecosystem.

Marine ecologist at Griffith University, Olaf Meynecke, states to The Guardian that this kind of targeted predation has been documented. "Why the liver is consumed is not entirely clear, but it could suggest a nutritional deficiency that the orcas are trying to compensate for," noting that in South Africa, orcas have contributed to the disappearance of great whites from certain areas. "This behaviour can have a significant impact on the distribution of great whites," he adds.

Beware of interactions between super predators

Adam Miller, the co-author of the study and associate professor in marine sciences and ecological genomics at Flinders University, indicates that these interactions between super predators could accelerate the decline of great white shark populations, reports GEO. "We know that great white sharks are key regulators of ecosystem structure and functions, so it's very important to preserve these super predators. Therefore, it's essential to monitor these types of interactions in Australian waters as much as possible."

(MH with Raphaël Liset - Source: GEO - Illustration: Unsplash)