CAPE TOWN, SOUTH AFRICA — Drone footage captured in 2022 showed five orcas working together to stun and kill a great white shark off the coast of Cape Town, South Africa, providing direct evidence of a predation pattern that researchers have linked to the disappearance of great white sharks from the region. The sharks were abundant in the coastal waters around Cape Town in 2010 but began disappearing from the area a few years later.

Signs of orca predation on sharks first emerged in 2015, when marine biologist Alison Kock received photographs of smaller shark carcasses on the sea floor bearing incision marks. "I initially assumed the incision marks had been made with a knife because they appeared surgical," Kock said. She and her colleagues went diving in the area where they had found a shark carcass and encountered two orcas beneath their boat, leading her to identify orcas as a possible culprit.

Two years later, great white shark carcasses with similar incision marks began washing ashore in the same area. Necropsies confirmed that orcas had been feeding on the sharks by eating their livers. A great white shark's liver comprises almost one third of its body mass and is its most calorie-dense organ.

Whale-watching tour operator David Hurwitz was the first person to observe two male orcas hunting and killing sharks off the coast of South Africa. He named the pair Port and Starboard. Unlike most orcas, which hunt in pods, Port and Starboard hunted sharks for their livers as a pair. Before these observations, no one had documented an orca killing a great white shark in South African waters, though orcas have inhabited the region's waters for years.

Kock said great white sharks fled farther up the coast after being hunted by orcas, though she believes the overall population of great white sharks in South African waters remains stable. Marine biologist Enrico Gennari, who has researched great white sharks in South Africa for 20 years, disagreed, saying the population is in decline. Gennari attributed the decline to human activities in addition to orca predation.

Since the 1950s, South African authorities have used shark nets and baited hooks attached to buoys to protect swimmers along the coast. Those measures kill more than 20 great white sharks annually. Commercial fishing boats also lay longlines with thousands of hooks on the ocean floor to catch smaller shark species, which are exported to Australia for use in fish and chips. Gennari described current shark protection methods as lethal, outdated and unsustainable, and proposed using underwater magnetic fields and smaller-meshed nets as nonlethal alternatives. "Losing the white shark in South Africa would constitute a loss for all nature and reflect a failure to protect other species against unsustainable use," he said.