Certain killer whales have a preference for liver, particularly that of great white sharks.
A video captured by Mexican scientists demonstrates how an astute whale targets the apex predator’s fatty organs.
Researchers documented two killer whale hunts in the Gulf of California, one in 2020 and the other in 2022. The footage reveals a group of great white sharks flipping a young shark onto its back, disorienting it, before slicing open its side to extract its liver. The findings from this video study were published on Monday in Frontiers in Marine Science.
In one notable scene, all members of the shark clan feasted on the pink liver fat while the remainder of the shark’s body remained submerged in the ocean depths. A sea lion was seen lurking nearby, seemingly hoping to steal a meal, but orcas released bubbles to ward it off.
Marine biologist and documentarian Eric Higuera Rivas, who filmed the hunt from a nearby boat, initially did not grasp the significance of the footage until he began editing.
“On the monitor, we noticed the shark’s liver hanging out, already dislodged. Moments later, the shark emerged with the liver in its mouth,” recounted Higuera Rivas, a co-author of the study. “I was astonished to learn it was a great white shark. I could hardly believe it.”
Heather Bowlby, a researcher from Fisheries and Oceans Canada not involved in the study, noted that the footage serves as a strong reminder that even apex predators need to stay vigilant.
“We typically view great white sharks as the pinnacle of the food chain,” she stated. “It’s always beneficial to remind them that they can also be prey.”
Higuera Rivas and his team indicated that the hunt appeared to involve members of the same group of killer whales, which they have designated as Moctezuma pods. This pod regularly patrols the Baja California coast, primarily hunting elasmobranchs, including sharks and whales. Higuera Rivas has been monitoring these pods and recording their behaviors for over a decade, noting their adaptations based on the species they target.
Previously, evidence of killer whales preying on great white sharks was limited to South Africa, where they have been known to extract livers and wash the remains ashore.
Alison Towner, a marine biologist at Rhodes University specializing in the South African phenomenon, stated that while behaviors in Mexico and South Africa are similar, they are not identical; Mexican killer whales typically target younger sharks, whereas their South African counterparts focus on adults.
Towner indicated that individual killer whale pods likely learned their hunting strategies independently.
“Observing this behavior in Mexico implies that specific groups of killer whales have developed distinct methods for hunting sharks,” she mentioned via email. “Even though the same organs are the target, the manner in which they are approached varies from what we have documented in South Africa, indicating group-specific learning.”
A new study reveals that Mexican killer whales have discovered a vulnerability in great white sharks.
“When flipped over, a shark enters a state known as tonic immobility,” explained study co-author Francesca Pancaldi, a shark researcher at the National Institute of Marine Sciences. “They become immobilized, akin to a catatonic state. They simply freeze.”
The liver, a nutrient-rich and fatty organ, comprises about a quarter of a shark’s body, delivering “a substantial amount of energy,” he added.
Researchers from both South Africa and Mexico concurred that this hunting behavior is likely not new to killer whales. What has changed for scientists is the advancement of drone technology, which has enhanced the ability to observe and document these hunting events.
“I believe this has been occurring for centuries, but it’s challenging to witness such events,” Pancaldi remarked.
However, she also mentioned that climate changes may have heightened interactions between great white sharks and the octopus pods.
“In fact, we have noticed a growing presence of great white sharks in the Gulf of California over the past decade,” Pancaldi noted, explaining that the species is particularly sensitive to changes in ocean temperatures linked to weather patterns such as El Niño.
According to Towner, scientists in South Africa began observing attacks by killer whales on great white sharks nearly a decade ago. Such predatory behavior has caused great whites to abandon their usual feeding, resting, and breeding spots, referred to as assemblages.
“As a result of repeated predation, great whites have entirely vacated their traditional core gathering sites,” Towner explained. “Many sharks may have relocated offshore or to less monitored regions, which is reshaping coastal ecosystems.”
Following the exodus of the sharks, populations of Cape fur seals and sevengill sharks have surged, leading to conflicts with the primary prey species, such as small fish and smaller sharks, according to the report. This study was published in Frontiers in Marine Science earlier this year.
Mr. Towner noted that only two adult male killer whales, referred to as Port and Starboard, were responsible for the frequent attacks on great white sharks in South Africa. This predation puts pressure on great whites, which have slow growth and reproductive rates, and a similar situation could develop in Mexico if this behavior becomes more prevalent.
Source: www.nbcnews.com
