The first killer whale-predated Great White Shark carcass washed up in Hartenbos, Mossel Bay on Sunday morning. A small incision can be seen in the belly, where the liver was removed and eaten by what seemed to be Orcas.
Alison Towner, a Marine Biologist, is currently leading research on these interactions between Orcas and Great White Sharks here in the Western Cape as part of her Ph.D. Towner conducts necropsies alongside her expert colleagues.
This is a very fresh sub-adult female Great White Shark, an already vulnerable population and reportedly the target of Orcas.
Great White sharks and rare short-toothed Orcas found in South Africa are top-order predators which often overlap across their cosmopolitan distributions.
In her studies, Towner and fellow experts documented the emigration of white sharks from Gansbaai, the Great White Shark capital of South Africa, in relation to a series of predations on white sharks by a pair of male orcas sighted between 2012 and 2020.
The pair were potentially responsible for predating on at least five white sharks in Gansbaai in 2017. The shark carcasses revealed a single large tear across the pectoral girdle, the liver—and in some cases, other internal organs—was missing, and rake marks were present on the fins.
As a result of these occasional predations by killer whales, rapid emigration of white sharks from the area became evident and the absence of white sharks led to a corresponding increase in bronze whaler sharks.
While further investigations are still very much needed, Towner’s studies suggest that predator–prey interactions between white sharks, other coastal sharks, and killer whales are increasing in South Africa and are expected to have pronounced impacts on ecosystem structure and function.
It will be available in the African Journal of Marine Science for two more weeks and is open access so you can download it and have a read.
“We have more science on its way out soon and I am more than willing to answer questions.”