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Cape Town's Great White Sharks have vanished.

This is interesting.

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Nobody knows where or why these apex predators have vanished to, but they have disappeared from their feeding grounds at Seal Island in False Bay, South Africa.

Their disappearance has never been recorded before, the city of Cape Town noted. Clearly, something is wrong in this particular ecosystem that is full of Cape fur seals, and it may be due to biosphere collapse.

Great white sharks, which support South Africa’s shark-diving industry and have been responsible for a number of fatal attacks off Cape Town, haven’t been seen in the region for 18 months.

Between 2010 and 2016 staff at the Shark Spotting Programme, established to warn swimmers when the three-ton predators approached beaches, reported an average of 205 sightings of the fish off the beaches of False Bay. In 2018 that fell to 50 and this year not one has been seen. None have been seen at Seal Island, a one-time feeding ground off the coast.

“Further supporting evidence of the absence of these large apex predators is the lack of any feeding or bite marks on whale carcasses the city has removed from False Bay this year,” Cape Town’s municipality said in a statement on Wednesday. “We do not know how their absence from False Bay would affect the ecosystem. Neither do we know the causes for their disappearance

Starving orcas were originally thought to be feeding on the sharks, but that has been dismissed as unlikely by marine biologists familiar with the area.

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Shark sightings fell by around a quarter in 2018, compared with average yearly sightings between 2010 and 2016.

More worryingly, not a single shark spotting has been reported so far this year.

Marine biologist Dr Sara Andreotti says claims that local killer whales in the area are to blame just don't add up.

“I cannot believe that two orcas would make an entire white shark population disappear from the most important site around the coastline.

— Dr. Sara Andreotti, Marine biologist 

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In 2012, experts put the population of great whites around the coast at around 300-500.

Given those figures, Andreotti says she's not surprised by the latest statistics.

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“We also did a genetic study to confirm this result and it confirms that the white shark population in South Africa was in very big trouble”.

Dr. Sara Andreotti, Marine biologist

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Cape fur seals on Seal Island.  “The island has become famous for the size of the sharks, and for their favoured way of catching their prey – a shark launching an attack will come up from underneath and hurl itself out of the water with the seal in its mouth. It has been shown that if the seals enter the “Ring of Death” (where the sharks circle the island) on the surface instead of at the murky bottom, they are more likely to be picked off by the faster and more aggressive great white”.
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Cape Town etc. provides additional information on the disappearance mystery. 

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“Further supporting evidence of the absence of these large apex predators is the lack of any feeding or bite marks on the whale carcases the City has removed from False Bay this year,” Nieuwoudt said. “To our knowledge the absence of great white sharks from False Bay has not been recorded or reported before.”

Great white sharks are apex predators and we do not know how their absence from False Bay would impact the ecosystem, or what has caused their disappearance.

Despite the lack of great white shark activity our tourism operators have managed to view seven gill sharks. Gill sharks were previously not present at Seal Island, and this confirms that there are changes happening within our ecosystem.

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The orcas agree that they are not to blame.

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