Orcas blamed for disappearance of S.Africa great white sharks

The numbers of great white sharks in the waters around Cape Town have steeply declined
The numbers of great white sharks in the waters around Cape Town have steeply declined

Killer whales are suspected to be behind the disappearance of great white sharks off Cape Town's coast over the last few years, according to a report published by South Africa's government on Tuesday.

The vanishing of great whites from the coastal sites False Bay and Gansbaai had previously been blamed on and overfishing, among other causes.

But the results of a study conducted by a government-appointed team of nine local and international experts suggest that orcas could be the culprits, after a pair of was first sighted in the area in 2015.

The researchers said they "found some evidence for a causative link between the appearances of a pod of orcas that had specialised on preying on ".

The number of great whites in the area is not known, but spotters initially reported steep declines in 2017—then an extended absence.

The remains of five killed by orcas were discovered in the Gansbaai area in 2017.

Another shark killed in a similar fashion was found on a beach this year, and there could be many more, a marine biologist and one of the researchers, Alison Kock, said during the report presentation.

"Each and every time that this happened, there was an immediate drop and gap in white sharks sighting," Kock said, conceding that "we still don't have all the answers".

Great white sharks are a big tourist attraction in South Africa—they are viewed from boats or from cages lowered into the water.

A great white shark pictured in waters off Gansbaii near Cape Town a decade ago—their numbers have steeply declined
A great white shark pictured in waters off Gansbaii near Cape Town a decade ago—their numbers have steeply declined

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Orcas prey on great white sharks in South African waters

© 2020 AFP

Citation: Orcas blamed for disappearance of S.Africa great white sharks (2020, November 17) retrieved 28 February 2021 from https://phys.org/news/2020-11-orcas-blamed-safrica-great-white.html
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