The Mystery of Cape Town’s Disappearing Great White Sharks

The coastal waters around Cape Town, South Africa, were once teeming with great white sharks. For about a decade, however, these majestic predators have been notably absent. Scientists and conservationists are at odds over the mysterious disappearance of the great whites and the potential suspects.

The Magnificent Whites

Historically, the ocean off Cape Town provided one of the best opportunities globally to observe great white sharks in their natural habitat. The area was rich with prey, including smaller sharks and tens of thousands of seals residing at Seal Island. Enthusiasts could watch these awe-inspiring creatures leap from the water in the early morning.

A decade ago, photographer and naturalist Chris Fallows documented 250 to 300 different great white sharks each year, capturing breathtaking images of these apex predators. He describes the experience as unforgettable, sharing the excitement of seeing such a powerful animal breach the water.

The Sudden Decline

The disappearance of great whites puzzled scientists, who first reported on the issue in 2010. Back then, thousands of visitors were drawn to the area for shark cage diving expeditions. However, sightings dwindled rapidly afterward, leading to a decline in tourism.

Chris Fallows notes that now, if one seeks out the sharks, the search is futile. Their numbers have dropped significantly, resulting in the near extinction of great whites in Cape Town’s waters.

Intriguing Investigations

The mystery of the disappearance prompted marine biologist Alison Kock to investigate further. In 2015, divers found smaller shark carcasses with unusual incisions. Initially, Kock suspected human involvement due to the surgical precision of the incisions.

Upon closer inspection, she found tooth marks on the pectoral fins of dead sharks. This evidence pointed away from human interference and suggested a new predator: orcas, known as killer whales.

Uncovering the Orca Connection

“The predator eats the prey.” — Alison Kock

Diving expeditions helped Kock confirm orcas as the culprits. During one dive, two orcas appeared under the boat just after a carcass retrieval, hinting at their role in the mysterious events. Orcas were known to hunt great whites off California and Australia, but this behavior was novel for South Africa.

In 2017, great whites began appearing onshore with their livers missing, a high-calorie organ targeted by orcas. Kock and her colleagues conducted necropsies, verifying orcas targeted the livers.

Tour operator David Hurwitz identified two distinct orcas, named Port and Starboard, hunting as a pair. Unlike typical orcas which hunt in pods, these individuals exhibited unique hunting behavior. There are even suggestions that Port and Starboard may be teaching others to hunt sharks.

The Human Factor

Despite the intriguing orca behavior, Fallows and marine biologist Enrico Gennari believe human activities are significant contributors to the decline. They have documented the effects of commercial fishing on smaller shark species, essential to the great white diet.

Longline fishing diminishes the sharks’ food supply. Furthermore, South Africa uses shark nets and hooks to protect swimmers, which also reduce shark populations. Fallows and Gennari suggest alternative methods, such as underwater magnetic fields, to protect swimmers and minimize environmental impacts.

Fading Protection

South Africa was the first country to protect great whites in 1991. However, efforts appear to have faltered, with Gennari fearing the country could lose the species altogether.

If South Africa cannot safeguard even a charismatic, protected species, the prospects for other marine life seem grim.

Lessons from Conservation

Chris Fallows has shifted his focus to photographing humpback whales, which have rebounded due to conservation efforts from the 1980s. He cites this as evidence that enlightened action can thrive.

By addressing human impacts on marine life, balance and health in the ocean can be achieved, benefiting both marine ecosystems and humans.

Produced by Michael H. Gavshon. Edited by Matthew Lev.