Orcas have been killing great white sharks off South African shores. But lately, there’s been a mysterious disappearance of great white sharks in these waters.
Scientists suggest that the remaining great whites who survived moved east to avoid trouble.
For years, great white sharks were turning up dead on South Africa’s False Bay and Gansbaai shores, missing something crucial – their livers.
Orcas had been extracting the sharks’ livers with chilling precision, killing them in the process.
Then, the sharks stopped washing ashore. They stopped swimming near those shores – some of their most well-known South African habitats – altogether. They were just gone.
A mysterious mass disappearance
“The decline of white sharks was so dramatic, so fast, so unheard of that lots of theories began to circulate,” Michelle Jewell, an ecologist at Michigan State University Museum, told Hakai Magazine.
People were worried that overfishing of both the food the sharks eat and the sharks themselves may have killed off large swaths of the population.
But a new study in the journal Ecological Indicators’ October issue indicated that the sharks didn’t die off; they were just hiding out in a new part of town, trying to avoid trouble.
Where great white sharks fled for their lives
By following reports of human-shark incidents, scientists determined the South African shark populations had shifted east to places such as Algoa Bay and the KwaZulu-Natal coastline.
“We know that predators have a huge influence on the movement and habitat use of their prey, so this isn’t really surprising,” Jewell told Hakai Magazine.
Through a process of elimination, the scientists in the study looked at the leading possible explanations, including prey decline in the region where the sharks disappeared and rapid reproduction in the areas where a large number of new shark sightings were reported.
Ultimately, they concluded the most likely explanation was that the great whites fled to avoid continued orca attacks. The study said its conclusion was supported by white shark behavior in other parts of the world.
In North America, for example, at the Southeast Farallon Islands, great white sharks have been recorded fleeing from hunting areas after orcas showed up.
Though many people think of the great white as an apex predator, this study is a prime example of the saying, “There’s always a bigger fish.”
“The indirect effect of predation (or the fear of predation) profoundly influences animal behavior,” the study said.
This article was originally published by Business Insider.
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