The Great White Shark Dilemma in South Africa: Orcas, Humans, and Conservation Challenges

The coastal waters around Cape Town, South Africa, have seen a significant decline in great white sharks over the last decade. Historically rich with these marine predators, the waters are now eerily quiet. Carcasses of these apex predators have been discovered with missing livers, leading to intrigue and scientific debate over the possible causes.

Approximately ten years ago, great white shark carcasses started to wash up on the beaches. Since then, sightings have decreased dramatically, creating a mystery that scientists and conservationists are eager to solve. They agree on one point: once abundant, great whites are now absent from these waters.

“The ocean off Cape Town was the best place to see great whites, with plenty of smaller sharks for them to hunt.”

Chris Fallows, a photographer and naturalist, has fond memories of seeing hundreds of great whites annually. His photographs captured the awe-inspiring spectacle of these sharks leaping from the ocean. But lately, Chris and visitors have reported a sharp decline in these encounters.

In 2010, visitors could experience close encounters with great whites during cage diving tours. But those days seem far behind us, as sightings on such tours have dwindled.

The disappearance has mystified scientists like Alison Kock, a marine biologist with South African National Parks. Kock began investigating this disappearance in 2015 when divers sent her photos of smaller shark carcasses with peculiar incisions, initially suspected to be human-induced.

“It looked so surgical that it seemed done by someone with a knife.”

Upon further inspection, Kock found tooth marks, ruling out human culprits. Subsequent dives revealed unexpected perpetrators—killer whales, known as orcas. These intelligent hunters were present near areas where carcasses had been found.

Necropsies later conclusively identified orcas as the culprits, targeting shark livers for their high calorie content. Orcas have interacted with sharks in various global locations, but this behavior was new for South African waters.

Yet, despite compelling evidence, scientists and locals are divided. Some argue human actions have driven away great whites by depleting their food sources and entangling them in shark nets.

David Hurwitz, a whale-watching operator, was among the first to observe orcas Port and Starboard hunting sharks in an unusual manner, earning them notoriety.

“The presence of just two orcas that would drive away hundreds of great whites?”

Researchers documented how Port and Starboard, unlike typical orcas, hunted together, teaching others their unique method. Yet, not everyone attributes the decline solely to orca activity.

Chris Fallows and marine biologist Enrico Gennari have documented the detrimental effects of human fishing on smaller shark species, essential to the great white’s diet. Commercial fishing has utilized longlines extensively, impacting the ecosystem.

“Shark longlining undoubtedly robs great whites of food.”

Moreover, shark nets along the coast have claimed many great whites. Gennari advocates for alternative conservation measures, arguing for the preservation of these critical predators.

While debates continue regarding the cause, the urgency to adapt conservation methods grows. South Africa was the first to protect great whites, yet may now face the unfortunate distinction of losing them without further intervention.

Conservation efforts elsewhere, such as the recovery of humpback whale populations following hunting bans, demonstrate success. Fallows hopes similar strategies can apply to restore great white numbers.

It’s a delicate balance to maintain ocean health; without proactive measures, critical species like the great white may fade away.