The first Orca predated Great White Shark has washed up in Hartenbos, Mossel Bay, a town in the Western Cape province of South Africa.
According to Alison Towner, a marine biologist, scuba instructor and skipper in South Africa, the first Orca predated white shark carcass washed up in Hartenbos, Mossel Bay last week. Towner, who is leading the research on these interactions between sea creatures, as part of a PhD, says she is “conducting the necropsies with expert colleagues on all of the shark carcasses here in South Africa.”
“It never gets easier seeing this.”
Alison Towner
Speaking about the shark that washed up, Towner said: “This is a very fresh sub adult female shark.” She also recommended anyone curious read the paper “Fear at the top: killer whale predation drives white shark absence at South Africa’s largest aggregation site,” which will be open access in the African Journal of Marine Science for another week or so.
When asked if this was becoming more common, and whether it was a learned behaviour that other Orcas could pick up on, Towner said: “Cultural transmission is a reality yes.” She was also asked whether it was the two “famous” orcas that have been reportedly attacked Great Whites before. She said: “Quite likely them but could be others.”
Another Instagram user asked how on earth Orcas manage such a clean taking of the liver. Towner responded: “They tear them open we have seen direct evidence of this. Sharks skin is very tough so raker marks (tooth impressions) are usually quite faint.”
When asked if there was any research being done to look into why orcas, or at least these two orcas, seem to be hunting food sources outside of their normal choices, Towner said: “This is their normal diet a paper by Foote came out recently explaining why Orcas shouldn’t be so heavily ecotyped in the N Atlantic… SA Orcas likely show more plasticity than their northern hemisphere counterparts.”
One commenter then chimed in with the following: “Given how endangered they are now, what do you think about taking steps to remove the 2 orca culprits (or are other orcas doing this in the region too now?) As awful as that would be, is it for the greater good in this instance?”
Towner said: “Lots of discussions ongoing as you can appreciate a very complex topic with very few clear-cut answers.”
In terms of whether this incident will change where Great Whites live, Towner said: “We have to follow the evidence and not speculate but… there could well be more movement away from Mossel bay now this is starting to repeat.”
Some commenters saw this as “Nature doing exactly what it’s supposed to do” and called it amazing, while others expressed their fears that the two Orca brothers may be part of a pod up to 100, and that they might pass this technique of shark predation on (“how many already know?”).
Towner also emphasised in a follow up post that Orcas are not the only pressure on the Great White population.
“More food for thought,” she said. “Time to be clear about something, again. Orcas are ONE pressure additionally now on Southern African white sharks. However, they are not the ONLY threat.”
She said white sharks were also under threat by fisheries and shark nets, with some studies concluding that shark nets were the worst culprits. Towner then said reducing this number is crucial, “especially in light of other threats this species faces.”
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