DNA evidence has confirmed that killer whales in Australia hunted a white shark to consume its liver. The research, led by Flinders University, analyzed DNA from bite marks on a large white shark carcass that washed up near Portland, Victoria, in 2023, which revealed that killer whales targeted the liver-rich mid-section.
For the first time, DNA evidence has confirmed killer whales in Australia hunted a white shark for its liver.
Using DNA analysis from the bite marks on the carcass of a large white shark that was found on a beach near Portland in Victoria in 2023, a study led by Flinders University has determined that killer whales were accountable for consuming the mid-section that includes the liver, known for being nutritionally valuable.
Killer whales (Orcinus orca) have been recorded hunting various shark species worldwide, including white sharks (Carcharodon carcharias), with prior observations in California and South Africa.
The find of a 4.7-metre-long white shark without its liver on a southeastern Australian beach allowed researchers to study its unique bite marks and pinpoint the predator.
“The liver, digestive system, and reproductive organs were absent, and there were four unique bite marks, with one being indicative of liver removal by a killer whale, akin to what has been documented in South Africa,” explained lead author Isabella Reeves, a PhD candidate affiliated with Flinders University’s Southern Shark Ecology Group and the West Australian Cetacean Research Centre (CETREC).
“We collected samples from the bite marks on the white shark and analyzed them for any residual genetic material from the predator. We confirmed killer whale DNA was present in the main bite area, while the remaining three marks showed DNA from scavenging broadnose sevengill sharks.”
“These results offer solid evidence of killer whale predation on white sharks in Australian waters, with strong indications of specific liver consumption. This hints that such predation events could be more common globally than previously thought.”
This research, published in Ecology and Evolution, utilized wildlife forensic methods to verify that killer whales were responsible for the removal and consumption of the liver from the white shark. Witnesses had observed several killer whales, including ones called ‘Bent Tip’ and ‘Ripple’, catching a significant prey in Bridgewater Bay just two days before the white shark carcass was found.
The large white shark carcass was retrieved by state fisheries officers for further investigation.
Killer whales in Australia have occasionally been seen preying on different shark species, such as blue shark (Prionace glauca), porbeagle (Lamna nasus), shortfin mako (Isurus oxyrinchus), and ground sharks (most likely school shark, Galeorhinus galeus). However, no documented instances of white shark liver consumption have been observed in Australia, despite numerous reports from California and the actions of the well-known killer whale duo ‘Port’ and ‘Starboard’ in South Africa.
Several reported interactions between killer whales and white sharks in Australia include at least one suspected kill in February 2015 at the Neptune Islands Group Marine Park in South Australia. On that occasion, an oil slick hinting at a successful predation was seen, although no carcass was retrieved to confirm the event.
Dr. Alison Towner, a marine biologist from Rhodes University in South Africa and a co-author of the study, noted that comparable killer whale predation on white sharks has caused shifts in local shark populations in both South Africa and California. “Nevertheless, direct observations of these interactions are rare, and their frequency is not well understood,” she stated.
Senior author and Flinders adjunct Associate Professor Adam Miller remarked, “We still lack clarity on how often these events occur in Australian waters and the significance of our findings. Evidence suggests that white sharks being disrupted or directly killed by killer whale predation in South Africa has led to significant changes in the broader marine ecosystem.”
“Given that white sharks play a vital role in regulating ecosystem structures and functions, it is crucial to protect these apex predators. Thus, monitoring these interactions in Australian waters is essential whenever possible.”
Dr. Lauren Meyer, a research fellow at Flinders University and another author of the study, added, “This research also reveals that killer whales facilitate scavenging by selectively consuming tissue, such as the liver and internal organs, while leaving substantial parts of the carcass behind, which benefits local ecosystems as a nutrient source.”
