Two orcas are eating white sharks off the coast of South Africa, according to US website Gizmodo. Called the Port and Starboard, they are said to have caused the death of eight great white sharks since 2017. Some carcasses have washed up on beaches across the country.
The wounds presented by the sharks and the records of the orcas in the same sea indicated to the research team that the orcas were responsible. According to results published in the African Journal of Marine Science, there could be more dead sharks.
Alison Towner, a marine biologist at the Dyer Island Conservation Trust, said orcas are highly specialized hunters. These animals can reach 9 meters in length, weigh over 7 tons and eat a variety of marine animals such as seals, dolphins, sharks and squid.
Great white sharks are not far behind and are strong opponents, being 6 meters long and having hundreds of sharp serrated teeth. Even so, they are being hunted by the orcas.
Towner’s team found that these sharks stopped frequenting coastal areas where orcas were hunting. “The more orcas frequent these places, the longer the great whites stay away.”
Because of this, orcas are altering the food chain: with white sharks leaving the area, the bronze whale shark, known to be eaten by great white sharks, is appearing there.
Orcas also eat animals of this species. Great white shark prey is also returning to the area in greater volume, such as seals, which are now eating African penguins.
Towner explained that this causes a domino effect. “To put it simply, while this is a hypothesis for now, there is some pressure that an ecosystem can withstand, and the impacts of shark removal by orcas are likely to have a big impact on the ecosystem.”