Posted by: The ocean update | July 20, 2016

South Africa’s great white sharks face extinction, says study

A great white on surface of the water in South Africa. Photograph: UIG/Getty Images

A great white on surface of the water in South Africa. Photograph: UIG/Getty Images

July 20th, 2016. Research shows ‘rapid decline’ in numbers caused by hunting, pollution and nets.

South Africa’s great white sharks face the threat of extinction after a steep decline in numbers caused by trophy hunting, shark nets and pollution, according to a study.

The six-year research project along the country’s coastline revealed that only between 353 and 522 of the sharks are still alive, half the level previously thought.

“The numbers in South Africa are extremely low. If the situation stays the same, South Africa’s great white sharks are heading for possible extinction,” said Sara Andreotti, the study’s author and a Stellenbosch University researcher, on Wednesday.

Scientists conducted the census by collecting biopsy samples and photographs of dorsal fins of the great predators, including in the Gansbaai area near Cape Town, a hotspot for shark-cage diving.

“We have come to the conclusion that South Africa’s white sharks faced a rapid decline in the last generation and that their numbers might already be too low to ensure their survival,” said Andreotti.

The study, published in the journal Marine Ecology Progress Series, also blamed shark nets, ocean pollution and baited hooks on the eastern seaboard of South Africa for the dwindling numbers.

“The chances for their survival are even worse than what we previously thought,” said Andreotti.

About 333 of the sharks are thought to be capable of breeding.

Although the great whites population has dropped off South Africa, the report said the sharks were still found in large numbers off the coast of Canada, Australia and the US.

The South African coast is notorious for shark attacks, with regular cases of surfers and swimmers being mauled to death.

Ref. : Andreotti S, Rutzen M, van der Walt S, Von der Heyden S and others (2016) An integrated mark-recapture and genetic approach to estimate the population size of white sharks in South Africa. Mar Ecol Prog Ser 552 : 241-253.

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