Shark safety programme Shark Spotters recorded a 4.9m female white shark found dead at a Gansbaai beach last week.
There was a large gaping hole between her pectoral fins where they were torn apart to reveal her body cavity, but it wasn't until a necropsy (animal autopsy) was performed days later that it was discovered that her large liver, which can constitute up to a third of her weight, was completely missing.
Shark Spotters says this information, combined with the recent sightings of Orcas and the disappearance of white sharks in the area, provides convincing evidence that the Orcas are responsible for the shark's death.
Further evidence mounted following the discovery of a second shark, a 3.5m male in the same area and with the same wounds, on Thursday.
Shark Spotters project manager Thomas Morris said the removal of the liver was indicative of an Orca attack.
On Sunday morning, Shark Spotters confirmed another shark had been found dead.
Morris said Orcas posed no danger to humans as they were not present close to beaches.
“We have had a very quiet season (sighting sharks) compared to others, and we have been interested to find out why. This shows us there has been a great collection of Orcas, moving sharks away from Gansbaai,” he said.
Department of Environmental Affairs spokesperson Zolile Nqayi confirmed that the two dead sharks washed up in Gansbaai were victims of predation, with their livers removed “and wounds and bite indentations consistent with what would be expected in an Orca attack”.
“Orcas have been spotted in and around False Bay and Gansbaai, with their occurrence appearing to be more common around the South African mainland in recent years,” said Nqayi.
He said killer whales commonly feed on marine mammals and seabirds, but have been known to feed on sharks, preferring the oil-rich liver to the rest of the carcass. Hence the carcasses being washed up with just the livers being removed.
Similar incidents have been recorded involving cow sharks in False Bay.