Port, front, and Starboard, the killer whales who have been killing great white sharks by making near-surgical cuts to their underbellies and then removing their livers.
Image: Dave Hurwitz/Simon's Town Boat Company
Jonathan Edwards
Esther Jacobs smelled murder on the water. As the pungent odor of shark liver filled the air and an oily sheen spread across the surface, Jacobs had come upon an aquatic crime scene - and two notorious serial killers.
They were the killer whales known as Port and Starboard who had been rampaging the Southern Cape coast. Their surprising victims: great white sharks.
Shark experts such as Jacobs have spent years trying to figure out how orcas - the largest of the dolphin family - are so easily dispatching some of the fiercest predators in the ocean, and why they’re using such grisly methods.
On her June 2023 voyage into Mossel Bay, Jacobs didn’t know that danger still lurked below. Then she spotted Port and Starboard - and watched the latter stalk a great white, disembowel its liver and then show off this gruesome trophy to a human audience on a nearby boat.
Starboard swims near the New Cape Point Lighthouse on the Cape of Good Hope in South Africa.
Image: Dave Hurwitz/Simon's Town Boat Company
“It was surreal,” said Jacobs, the founder of Keep Fin Alive, a marine conservation and education nonprofit. She added: “I’ve always seen [great white sharks] as this incredibly powerful apex predator. So to see one just get picked off so easily … it’s really mind blowing.”
What Jacobs witnessed was one of dozens of times experts say the pair has killed sharks, many of them great whites. Marine biologists have been stunned by the killer whales creating near-surgical cuts in great whites’ underbellies, removing their livers and leaving them to die, sometimes within minutes.
“They can handle a white shark and just shuck it like a mussel almost - just tear it open and slide its liver out and consume it and discard the rest,” said Alison Towner, a marine biologist at Rhodes University in South Africa.
While other killer whales have been documented preying on sharks in the area, Port and Starboard are believed to be the primary offenders. They usually work together, but scientists believe they are part of a larger group from which they often break off to hunt.
The killings have had far-reaching implications. To steer clear of the roving killer whales, researchers say, great white sharks have fled their former favorite haunts, causing cascading effects up and down the food chain. Populations of the great whites’ food, including Cape fur seals, have spiked - and these animals in turn have grown bolder while feasting more heavily on their prey. There are tourism impacts, too: TV crews that once routinely made an annual pilgrimage to South Africa to capture great white footage now go elsewhere.
“I can’t believe we still, in less than a decade, have seen such profound impacts,” Towner said.
Port swims in False Bay on Feb. 2 while tourists with Simon’s Town Boat Company watch him. It was the last recorded sighting of him.
Image: Derek Goldman
A decade ago, great white and sevengill sharks ruled False Bay. They preyed on bony fish, rays, small cetaceans and other sharks.
They were also some of the bay’s marquee stars, fueling an ecotourism industry that includes scuba diving, cage diving and boat tours. Divers could routinely observe dozens of them during an hour-long dive on the west side of the bay at Miller’s Point, which one website hailed as “the epitome of shark diving worldwide.”
But starting in 2009, tourism boats started documenting the arrival of another predator: killer whales. Over the ensuing years, although the number of orcas in False Bay increased, the apex predators coexisted, with the orcas feeding on marine mammals, especially common dolphins and whales such as the humpback.
“Their presence was very rare in that area,” said Alison Kock, a marine scientist with South African National Parks who has been studying False Bay’s sevengills.
Then came Nov. 9, 2015. Cage divers at Miller’s Point hoped to be dazzled by the bustling sevengill population - only to find that the sharks had vanished overnight, even though the population usually peaks in the Southern Hemisphere’s late spring. Instead, divers soon found several sevengill carcasses, each with a gaping wound on its underbelly near the pectoral fins.
Researchers assumed humans must have been responsible. Fishers had long favored using oily shark liver as bait for other sharks, Kock said. And marine biologists didn’t think any animal could so precisely target a particular organ.
“We really didn’t know what had caused this,” Kock said.
Then in April 2016, several more carcasses were found littered on the seabed and at Miller’s Point. This time, divers recovered them, allowing Kock and other marine biologists to perform necropsies. She found that, like the sharks killed the previous November, the ones being examined had a gaping wound across their pectoral girdle with little other damage. Their hearts, stomachs and other major organs were still intact - with one exception.
“In each case, the liver had been removed,” wrote Tamlyn Engelbrecht, who co-authored a 2019 paper with Kock titled, “Running Scared: When Predators Become Prey.” Engelbrecht also noted that shark livers, which can account for up to a third of a shark’s body weight, are high in fatty energy-rich lipids.
Marine biologists found bite marks on the sharks’ pectoral fins and bruising of the underlying tissue. Armed with these observations, they reexamined photographs of the sharks that had been killed five months earlier and found the same kinds of bite wounds on their pectoral fins, which had also been marred by rake marks - scratchlike injuries caused by orcas when they scrape victims with their teeth.
The scientists had cracked the case: Their killers were killer whales.
It was a shocking discovery. Killer whales eat a wide range of food as a species, from fish to squid to marine mammals such as seals. But different groups often have specialized diets based on culture. While orcas had been documented eating sharks, instances of them targeting bigger ones at the top of the food chain were rarer.
What happened was rarer still. It was the first time - anywhere - that anyone had recorded killer whales using force to extract a shark’s liver.
Up to that point, Kock had focused her research on sharks - while many of her impressions of killer whales grew out of “Free Willy,” a 1993 movie in which a 12-year-old boy befriends and helps free an orca whose owners plan to kill him for insurance money. Kock’s discovery upended the movie’s heartwarming depiction of the animals, which can grow up to 32 feet and weigh as much as 11 tons.
“Seeing their immense impact on white sharks and how they prey on them, and how Hannibal Lecter it is, I think that ‘Free Willy’ really was a bit of a lie, and ‘Silence of the Lambs’ was a little bit more accurate,” she said.
Researchers quickly homed in on two suspects.
A Marine Dynamics team member handles the carcass of a female great white shark that washed ashore on May 3, 2017, near Gansbaai. Marine biologists discovered that a killer whale had eaten the shark's liver.
Image: Marine Dynamics
A pair of killer whales were spotted for the first time in 2012 at the far south end of False Bay near the Cape of Good Hope. The two males, who were eventually nicknamed Port and Starboard because their dorsal fins had collapsed in opposite directions, then disappeared for three years.
They showed up in the bay again in January 2015 and were spotted multiple times there over the next 10 months, including just days after the sevengill attacks in November of that year. As Kock and her team performed two dives in the wake of the second sevengill massacre in April 2016, they approached their boat. Kock compared sighting records of Port and Starboard from dive boat operators to the places where carcasses had been found - they matched up.
She had found the shark killers.
But the carcasses kept coming. Dave Hurwitz, the owner of the ecotourism business Simon’s Town Boat Company who nicknamed the killer whales, said about 20 sevengill sharks were killed that year.
And those are just the ones that washed ashore or were found by divers, he added. Because shark corpses sink, a combination of factors, including tides and currents, have to align for their bodies to be discovered. Undoubtedly, experts said, many more have sunk to the ocean floor.
The following year, Port and Starboard turned their attention to bigger game. The first great white shark carcass washed ashore in February 2017, in Gansbaai, a town about 35 miles southeast of False Bay. Over the next several months, four more were found, all with tears to their underbelly near their pectoral fins and none with livers.
Marine biologists also found rake marks on their bodies, leading Towner and others to conclude that the creatures that had been hyped into sea monsters by “Jaws” and Discovery Channel’s Shark Week had become prey.
“All of a sudden, they’re the victims,” she said of the sharks. “So it really did turn everything on its head.”
Marine biologists don’t know why they started hunting off the coast in the first place. Killer whales usually rove farther offshore, and Port and Starboard were already adept killers with well-honed hunting skills when they arrived, Jacobs said. She thinks they were forced in but said that experts haven’t figured out why, although they have theories that include overfishing.
“No one really has any idea,” she said.
The effects of Port and Starboard’s decade-long hunting campaign have been pronounced and enduring, for the sharks most of all, especially because they’re the most threatened fish in the ocean, Towner said.
Humans are their biggest danger. About 70 percent of sharks face serious pressure from overfishing, which is rampant and off the radar in southern Africa, Towner said. Climate change has altered ocean conditions, which is modifying the travel patterns of their prey and for sharks themselves. And underwater shark nets, designed to protect swimmers, trap and kill sharks. Orca predation only adds to their woes, Towner said.
Port and Starboard are still terrorizing the South African coast. One marine biologist described them as “roving bandits” looting the coasts of southern Africa, as far north as Walvis Bay in Namibia and as far east as Algoa Bay in South Africa. Most recently, in October, Port and Starboard killed more sevengills in nearby bays.
No one knows where they are now, but biologists say it’s only a matter of time before they show up again - and leave a watery graveyard in their wake.