One of the biggest and best known populations of great white sharks live off the coast of South Africa. So when their behaviour changed in 2017, and they were seen far less regularly, scientists raised alarm bells fast.
Yet, it seems that the reason is far more simple. Great white sharks appear to sit at the top of the food chain, but they do not. The true apex predator of the sea, is the Orca or killer whale. During 2017 5 carcasses washed ashore, each with liver eaten, and one had had the heart consumed as well. Now it is believed that just 2 Orca are responsible for these attacks, though there is much suspicion that other Orca must also be behaving in the same way, as it seems unlikely that just 2 animals could have such a big impact.
Gansbaai is a famous shark watching destination close to Cape town, but the great whites are increasingly absent. This is rather unbalancing the ecosystem, with smaller sharks proliferating and decimating the numbers of prey species, which has largely upended the whole system.
This behaviour of displacing great white sharks has been seen before, off the coast of San Francisco, but this is the first time its been seen in South Africa.