Two orcas whales are hunting and eating great white sharks, according to new research.
A recent article in アフリカ海洋科学ジャーナル focuses on two killer whales researchers have discovered that hunt great white sharks off the coast of South Africa. The whale pair’s appetite for great whites has sent the sharks fleeing out of the area.
“最初は, following an orca attack in Gansbaai, individual great white sharks did not appear for weeks or months,” the article’s lead author, Alison Towner, SWNSに語った.
“It mirrors what we see used by wild dogs in the Serengeti in Tanzania in response to increased lion presence,” 彼女は付け加えた. “The more the orcas frequent these sites, the longer the great white sharks stay away.”
According to the article’s findings, 以来 2017, eight great white sharks have washed up dead on South African shores with identifiable orca bite marks.
Seven of those sharks had their livers removed by the whales during the attack, and some of them had their hearts removed too. All of the dead sharks found had distinctive wounds traced to the same pair of killer whales.
Researchers believe the orcas have killed more than the eight great whites found washed up on shore and that other killer whales are capable of similar attacks.
Orcas are the iconic great white shark’s only predator — apart from humans. The whales can reach up to 30 feet in length and weigh over six tons — feeding on fish, squid, seals, and sea birds. Great whites can reach up to 22 feet long and weigh around 2.5 トン.
Towner, a Ph.D. student at Rhodes University in Makhanda, 南アフリカ, said that this research “is particularly important” because it determines “how large marine predators respond to risk.”
She added that the research can also help scientists understand the “dynamics of coexistence” の間に “other predator communities.”
Towner’s recently published study used long-term sightings and tagging data to show that the two orcas have scared great whites away from South Africa’s Gansbaai coast, which the sharks dominated for years. Located 60 miles east of Cape Town, Gansbaai was known for great white sightings.
Towner, a senior biologist at the Dyer Island Conservation Trust off the southern tip of Africa, lives in Gansbaai and has witnessed firsthand how the two shark-hunting orcas have driven great whites out of the area and changed the sea’s ecosystem.
“It’s triggered the emergence of a new mesopredator to the area, the bronze whaler shark, which is known to be eaten by the great white shark,” 彼女は説明した.
“Balance is crucial in marine ecosystems. 例えば, with no great white sharks restricting Cape fur seal behavior, the seals can predate on critically endangered African penguins or compete for the small pelagic fish they eat,” Towner added.