It is hard to imagine that great white sharks have a predator it is scared of but they do. Scientists have discovered that orcas have been causing these top predators to leave their stomping grounds.
In 2017, researchers noticed that great white sharks have become scarce off the coast of South Africa. At first, they attributed the scarcity to humans and overfishing. Now they believe a pair of orcas are actually to blame.
A small fishing town on the Southern African coast, Gansbaai, use to be heavily populated with sharks. The town was such a mecca for the predators that the nearby Dyer Island was treated as the great white shark capital of the world.
Over the past five years, there have been eight great white sharks that have washed ashore in Gansbaai. Seven of them had no liver and many didn’t have their hearts. This is the hallmark sign of an orca attack. Killer whales enjoy hunting sharks and slurping out their nutritious, vitamin-rich livers.
The injuries on the sharks are distinctive and have been traced to the pair of orcas roaming the South African coast. Researchers believe the pair is responsible for many more great white shark deaths; they just haven’t washed ashore.
Previous studies indicate that the presence of orcas can drive great whites from the area. A 2020 study showed that predator sharks will flee from their preferred hunting grounds if an orca makes an appearance in the area.
Marine biologist Alison Towner of the Dyer Island Conservation Trust led a team of scientists in a study using long-term sighting and tracking data from tagged sharks. The information they gathered proved that orcas are the reason sharks are avoiding their favorite stomping grounds.
Great white sharks avoided the area “for weeks or months” right after “an orca attack in Gansbaai,” according to Towner.
Over the course of the past five years, the team has tracked 14 sharks that had been GPS tagged as they hightailed it from the area when orcas were present.
This has many people wondering if it could happen in other areas of the world.
Great white shark appearances have become more frequent off the coast of Massachusetts. New England Aquarium’s John Chisholm stated, “When there have been orca sightings here through the years, they’ve never really seemed to impact the white sharks in the area.” He also verifies shark sighting reports on the Atlantic White Shark Conservancy’s Sharktivity app.
Only “Time will tell” on whether or not orcas will have the same impact on shark sightings in the New England area, he added.
Written by Sheena Robertson
Sources,
Boston Herald: Two orcas killing great white sharks are scaring away sharks in South Africa. Could that happen along Cape Cod?
Science Alert: Great White Sharks Are Being Scared From Their Habitat by Just Two Predators
Top and Featured Image Courtesy of Elias Levy‘s Flickr Page – Creative Commons License
Inset Image Courtesy of Diana Padrón‘s Flickr Page – Creative Commons License
