Scientists in South Africa have released a study featuring the first known footage of orcas (killer whales) predating on great white sharks.
Taken from drone and helicopter footage filmed over Mossel Bay earlier in 2022, the video shows a pod of orcas killing multiple great white sharks during an hour-long hunt. Although some of the footage was broadcast in June, the complete picture has only been described in a more detailed study led by Alison Towner of the Department of Ichthyology and Fisheries Science at Rhodes University.
‘This behaviour has never been witnessed in detail before, and certainly never from the air,’ said Towner, who is the senior shark scientist at Marine Dynamics Academy in Gansbaai, South Africa.
It is not the first time that orcas have been linked to the deaths of great white sharks. Carcasses washed ashore during a spate of great white shark deaths in 2017 were found to have bite marks indicating that they had been killed by orcas and had their fatty livers removed ‘with surgical precision’
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Two killer whales – named ‘Port’ and ‘Starboard’ – were thought to be responsible for the predation, but were never actually caught in the act. Their presence in the Mossel Bay area, however, appeared to drive the great white population elsewhere, with only a single shark being seen for 45 days in the aftermath of the attacks.
‘We first observed the flight responses of seven gills and white sharks to the presence of killer whales Port and Starboard in False Bay in 2015 and 2017,’ said Dr Alison Kock, co-author of the study and South African National Parks marine biologist. ‘The sharks ultimately abandoned former key habitats, which has had significant knock-on effects for both the ecosystem and shark-related tourism.’
The footage also gives new insights into how the sharks attempted to evade the hunting orcas. The sharks – which have no other known predator – stayed close to an approaching orca, circling tightly to keep it in view – the same strategy used by seals being hunted by great whites. Unlike sharks, however, which are solitary hunters, orcas are wily pack hunters, and the strategy ultimately failed as other members of the pod raced in for the kill.
‘Killer whales are highly intelligent and social animals,’ said Dr Simon Elwen, research associate at Stellenbosch University and another of the study’s co-authors. ‘Their group hunting methods make them incredibly effective predators.’
The orca known as Starboard was identified as one of the members of the five-member pod that was recorded hunting the sharks, suggesting that the behaviour may be spreading. Killer whales are known to adopt newly learned behaviours from their peers.
Towner’s study suggests that if the shark-hunting behaviour continues to spread, there may be greater impacts for the region’s shark populations in the future.
The complete paper ‘Direct observation of killer whales predating on white sharks and evidence of a flight response’ by Alison V Towner et al is published by the Ecological Society of America online journal, DOI: 10.1002/ecy.3875
