For decades the waters off Cape Town around Seal Island were world‑renowned for great white sharks. Photographers, researchers and cage‑diving operators regularly recorded hundreds of individuals each season; dramatic surface breaches became a tourism draw and a pillar of local wildlife business.
That changed about ten years ago. Sightings dropped dramatically and the sharks stopped coming to the island. Beginning around 2015 divers and marine biologists began recovering small shark carcasses on the seafloor with clean, surgical‑looking cuts and missing livers. South African National Parks marine biologist Alison Kock examined these remains and found tooth marks on pectoral fins and other signs that something was targeting juveniles and, later, removing the calorie‑rich livers of larger animals. The liver is an efficient prey item for a predator that can disable a shark and take only that organ.
Kock and colleagues concluded the culprits were killer whales. Two unusual male orcas, nicknamed Port and Starboard because their collapsed dorsal fins tilt left and right, were filmed hunting sharks in the region. Drone and boat footage captured orcas stunning great whites and extracting their livers; necropsies of washed‑up great whites confirmed livers had been removed by orca bites. In several cases the same orcas were later observed feeding on sharks near where carcasses had been found.
Scientists describe two linked effects from this novel predation. Orcas sometimes kill sharks outright, but perhaps more importantly their presence appears to alter shark behavior: sharks avoid places where orcas hunt, creating a “landscape of fear” that displaces them from traditional hunting grounds like Seal Island. Kock argues that a small number of orcas can drive many great whites away along the coastline, and that orca learning and social transmission of shark‑hunting techniques could magnify the impact. Later video shows more orcas working together to stun and dismember large sharks.
Not everyone agrees that orcas explain the whole story. Enrico Gennari, who has studied South African great whites for decades, and photographer Chris Fallows emphasize long‑standing human pressures that predate the orca attacks and could have already reduced shark numbers. They document extensive commercial longline fishing and targeted shark longlining that remove smaller shark species important to great white diets, and the use of shark nets and baited hooks meant to protect beaches. Those lethal mitigation measures have killed many sharks — including protected great whites — for years. Gennari notes that great white numbers had fallen significantly before Port and Starboard appeared near Seal Island, and he worries that loss of prey and ongoing bycatch make recovery less likely.
Global comparisons are mixed. In California and Australia orcas have also killed great whites, but the whites later returned; at Seal Island a return has not yet been observed. Kock maintains that the local population overall may still be stable and favors a displacement explanation for the absence at Seal Island, while Gennari and Fallows argue the population has declined and that human activities are the decisive factor. Everyone agrees on one point: the large numbers of great whites people once saw near Seal Island are now rare or absent.
That disagreement matters because management responses differ sharply depending on the cause. If orcas are the main driver there is little humans can directly change. If fisheries and coastal mitigation are the primary causes, there are concrete policy options: stricter regulation of longline fisheries, reducing or replacing lethal shark‑control gear, and adopting less‑lethal deterrents. Suggested alternatives include magnetic or electrical exclusion devices, improved net designs or exclusion barriers that reduce bycatch, and modernization or removal of baited hooks and nets that kill non‑target species.
South Africa protected great whites legally in 1991, but some researchers say protection on paper has not eliminated lethal pressures from fisheries and beach safety programs. If a high‑profile, legally protected apex predator like the great white can decline under current practices, they argue, it signals broader gaps in marine conservation and enforcement.
Advocates for conservation note the ecological stakes: great whites are apex predators whose presence shapes prey populations and habitat dynamics. The situation has prompted comparisons to other recoveries — humpback whales nearly vanished under commercial whaling but rebounded after sustained protection and fisheries changes — suggesting that reducing human pressures can allow recovery given enough time and effort.
Meanwhile, local photographers and tour operators have adapted. With few great whites at Seal Island in recent years, some have shifted effort to other species such as humpback whales, whose comeback offers a hopeful example of targeted conservation. Scientists continue to collect data: monitoring shark movements, tracking orca behavior and social learning, and pressing for policy changes that address human drivers many fear are compounding the orca effect. The fate of the once‑famous Cape Town great white hotspot remains uncertain, and researchers emphasize the need for better data and clearer management choices to give the population a chance to recover.