Orcas have a taste for shark liver and prey on great white sharks in Australian waters, researchers have confirmed using DNA analysis.
In October 2023, the maimed carcass of a 4.7m great white shark washed ashore near Portland, in southwest Victoria, missing its liver, digestive and reproductive organs.
Two days earlier, citizen scientists witnessed several killer whales, including locally catalogued animals known as Bent Tip and Ripple, catch large prey in the area.
Photo: Ken Balcomb, Center for Whale Research via AP
Suspecting a killer whale was the behind the shark’s death, researchers swabbed and analyzed DNA samples taken from the distinctive bite wounds.
The results, published this week in Ecology and Evolution, confirmed the presence of killer whale DNA in the area around the largest bite, a wound measuring 50cm in diameter near the shark’s pectoral fin. Tests also found the presence of genetic material from scavenging broadnose sevengill sharks in three smaller bite wounds.
That was the first confirmed evidence — using DNA and citizen science data — of orca predation on great white sharks in Australia, and their likely selective eating of shark liver in Australian waters.
Isabella Reeves, a Flinders University researcher and the lead author of the findings, said “killer whales and white sharks are both top predators.”
The carcass found in Victoria had “four distinctive bite wounds,” she said, one of which showed killer whales had deliberately torn out its liver.
The phenomenon was previously observed off South Africa, where in one published case, an individual orca incapacitated a great white and ate its liver in less than two minutes.
“It shows we’re probably really underestimating how often and where this behavior is actually occurring,” Reeves said.
She said understanding what orcas eat and their nutritional needs could help with preserving them, their prey and the rest of the ecosystem.
The paper said that killer whales have previously been recorded specifically choosing certain organs, such as whale tongue, as well as shark liver.
Orcas, often referred to as the “wolves of the sea,” get their hunting advantage from “their exceptional intelligence, strong family and social bonds, and their ability to work together in highly synchronized pods” — able to work in packs to bring down prey as large as great white sharks and blue whales, said Rebecca Wellard, a marine scientist based at Project ORCA and Curtin University who was not involved with the study.
Griffith University marine ecologist Olaf Meynecke, also not involved in the study, confirmed that killer whales were known to eat particular body parts.
“Why the liver is eaten is not fully clear, but could suggest a nutritional deficiency that the orcas try to compensate for,” he said.
“In South Africa, sharks have disappeared in areas when orcas are around,” he said. “So this behavior can have a strong impact on white shark distribution.”
A humanoid robot that won a half-marathon race for robots in Beijing on Sunday ran faster than the human world record in a show of China’s technological leaps. The winner from Honor, a Chinese smartphone maker, completed the 21km race in 50 minutes and 26 seconds, said a WeChat post by the Beijing Economic-Technological Development Area, also known as Beijing E-Town, where the race began. That was faster than the human world record holder, Ugandan Jacob Kiplimo, who finished the same distance in about 57 minutes in March at the Lisbon road race. The performance by the robot marked a significant step forward
Four contenders are squaring up to succeed Antonio Guterres as secretary-general of the UN, which faces unprecedented global instability, wars and its own crushing budget crisis. Chile’s Michelle Bachelet, Argentina’s Rafael Grossi, Costa Rica’s Rebeca Grynspan and Senegal’s Macky Sall are each to face grillings by 193 member states and non-governmental organizations for three hours today and tomorrow. It is only the second time the UN has held a public question-and-answer, a format created in 2016 to boost transparency. Ultimately the five permanent members of the UN’s top body, the Security Council, hold the power, wielding vetoes over who leads the
An earthquake registering a preliminary magnitude of 7.7 off northern Japan on Monday prompted a short-lived tsunami alert and the advisory of a higher risk of a possible mega-quake for coastal areas there. The Cabinet Office and the Japan Meteorological Agency said there was a 1% chance for a mega-quake, compared to a 0.1% chance during normal times, in the next week or so following the powerful quake near the Chishima and Japan trenches. Officials said the advisory was not a quake prediction but urged residents in 182 towns along the northeastern coasts to raise their preparedness while continuing their daily lives. Prime
South Korea’s air force yesterday apologized for a 2021 midair collision involving two fighter jets, a day after auditors said the pilots were taking selfies and filming during the flight and held them responsible for the accident. “We sincerely apologize to the public for the concern caused by the accident that occurred in 2021,” an air force spokesman told a news conference, adding that one of the pilots involved had been suspended from flying duties, received severe disciplinary action and has since left the military. The apology followed a report released on Wednesday by the South Korean Board of Audit and Inspection,
RSS