For decades the stretch of ocean off Cape Town around Seal Island was one of the world’s best places to see great white sharks. Photographers and tour operators once counted hundreds of different individuals each year; visitors came in cages for dramatic surface breaching, and local tourism revolved around the predators.
About a decade ago that changed. Sightings dwindled and sharks stopped coming to the island. Around 2015 divers and marine biologists began finding smaller shark carcasses on the seafloor with mysterious, surgical-looking cuts and missing livers. South African National Parks marine biologist Alison Kock examined retrieved carcasses and found tooth marks on pectoral fins and evidence that something was targeting small sharks and, later, the livers of great whites. The liver is calorie-dense and makes an efficient meal for a predator that can disable a shark and take only the organ.
Kock and others concluded killer whales — orcas — were responsible. Two strange male orcas, nicknamed Port and Starboard because their collapsed dorsal fins lean left and right, were observed hunting and killing sharks in the area. Drone and boat footage showed orcas stunning great whites and extracting livers, and necropsies of washed‑up great whites confirmed livers had been removed by orca bites. In some cases orcas were later seen feeding on the sharks in the same areas where carcasses had been found.
Scientists propose several related effects from this novel predation. Orca presence can kill some sharks directly, but perhaps more importantly it can change shark behavior: sharks may avoid areas where orcas hunt, creating a “landscape of fear” that displaces them from traditional hunting grounds such as Seal Island. Kock argues that a small number of orcas can drive away many great whites across the local coastline, and that orca learning and social transmission of shark‑hunting techniques may amplify the effect. Video from later years shows more orcas working together to stun and dismember great whites.
Not all researchers agree that orcas explain the full story. Enrico Gennari, an Italian scientist who has studied South African great whites for decades, and photographer Chris Fallows point to major human impacts that predate orca attacks and could have reduced shark numbers. They document extensive commercial longline fishing and shark longlining that remove smaller shark species important in the great white diet, and the use of shark nets and baited hooks to protect beaches. These lethal mitigation measures have caught and killed many sharks — including protected great whites — for decades. Gennari notes that great white numbers fell substantially before Port and Starboard were ever seen near Seal Island, and he worries that losing prey and suffering ongoing bycatch mortality makes a population decline more likely and harder to reverse.
Other comparisons show varied outcomes elsewhere. In California and Australia orcas have killed great whites but the whites later returned; in South Africa the return has not yet been observed at Seal Island. Kock contends the local population overall remains stable and proposes displacement rather than extirpation at Seal Island, while Gennari and Fallows argue the population has been reduced and human pressures are the decisive factor. The two sides agree on one thing: the nearby great whites that people used to see in large numbers are now rare or absent.
The conflict has sparked a bitter debate among scientists and conservationists because the management responses differ depending on the perceived cause. If orcas are the main driver, there is little humans can directly do about it. If human activities — longlining, nets, baited “shark control” hooks — are primary, there are concrete policy choices. Critics of current approaches say South Africa still relies heavily on lethal shark mitigation: gear that intentionally kills large predators to reduce human encounters. Researchers suggest alternatives used elsewhere: less‑lethal deterrents (magnetic or electrical barriers, improved net designs or exclusion devices), better regulation of longline fisheries, and removal or modernization of lethal beach protection methods that take non‑target species.
South Africa protected great whites in 1991, but some scientists say legal protection alone has not eliminated lethal pressures from fisheries or from coastal mitigation programs. If a charismatic, legally protected species like the great white can decline under current practices, they argue, it signals wider failures for marine conservation.
Those who study and photograph marine life emphasize the broader stakes. Great whites play important roles as apex predators in ocean ecosystems, and their presence affects prey and habitat dynamics. The story has also prompted comparisons with whales: humpbacks were hunted nearly to extinction but rebounded after sustained conservation efforts. Some argue that if humans reduce or remove pressures — by changing fisheries, updating beach safety methods, and improving enforcement — populations can recover.
Meanwhile, photographers and tour operators have adapted. With few great whites at Seal Island in recent years, some have shifted efforts to other species, such as humpback whales, whose comeback shows what targeted conservation can achieve. The fate of the once‑famous Cape Town great white hotspot remains uncertain: researchers continue to collect data, monitor orca behavior, track shark movements, and press for policy changes that address the human drivers that many fear are compounding the orca effect.
