South Africa: where are the great white sharks?

South Africa: where are the great white sharks?

Science

No sightings of large white sharks were reported this year in False Bay, South Africa, which is usually one of the most frequented by predators. Orcs, but also Men, would be guilty of this absence.

On average, an average of 200 sightings of large white sharks occurs annually in False Bay, Cape Town, South Africa. But 2019 seems to be an exception. Sharks tagged along the South African coast did not send any signals. This is no longer the case since 2017. Shark Spotters, an association that monitors daily the beaches of the area, explains for its part has not observed the predator this year. Boats are offering tourists a meeting with the big white either. Nobody. How to explain this absence? How is it that this species, used to frequent these South-African beaches, has been as discreet since a few months? For the researchers, there would be two culprits.

Orca, on the one hand.

We learn that the attendance of large whites in the region began to decline since 2015. A date that coincides with the appearance, offshore, two orcas. These two large predators have been observed hunting flat-nosed sharks in the region. But we also know that the presence of orcas causes excellent white sharks to flee. This is at least the report that was made a few months ago off California. Some sharks, following the simple passage of orcas, moved elsewhere before returning the following season. So the same thing may be happening now in South Africa.

Several white sharks found dead seem to confirm this hypothesis. The carcasses all had the missing liver. A nutritious dish, we know, very popular with orcas.

Is man so guilty?

Several researchers, such as biologist Sara Andreotti of the University of Stellenbosch in South Africa, also point to human interference. “Overfishing and pollution are also likely to play a role,” she says. My concern is that the focus on orcs is diverting attention away from other issues that humans may be solving. ” Further studies will be needed to assess the leading causes of this absence.

Note also that the great whites have not completely disappeared from the region. Some specimens have been seen in Gansbaai – still in South Africa – less than 100 kilometers east of False Bay. Local officials are concerned, however, about the impact of this lack of predators in the region, which hosts many tourists every year to see it. In the meantime, nature has not wasted time. Several other species of sharks have already invested the niche left vacant to hunt seals.