For years, great white sharks were turning up dead on South Africa’s False Bay and Gansbaai shores missing something crucial — their livers.
Killer whales had been extracting the sharks’ livers with chilling precision, killing them in the process.
Then, the sharks stopped washing ashore. They stopped swimming around those beaches , some of which are their best-known South African habitats. The sharks were 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 worried that overfishing of both the food the sharks eat and the sharks themselves may have killed off large swaths of the population.
But, it turns out that the sharks didn’t die off, they were just hiding out in a new part of town, trying to avoid trouble, according to a new study in the journal Ecological Indicators’ October issue.
Where great white sharks fled for their lives
By following reports of human-shark incidents, scientists determined that the South African shark populations had shifted east, to places like Algoa Bay and the KwaZulu-Natal coastline.
“We are aware that predators can have an impact on their prey’s habitat and movement, which is why this phenomenon shouldn’t be surprising,” Jewell said to Hakai Magazine.
The scientists used a method of elimination to examine the most likely explanations, including a decline in prey in the area where the sharks vanished and rapid reproduction where there were many new sightings of sharks.
Ultimately, the scientists concluded that the most likely explanation is that the great whites fled to avoid continued killer whale attacks. The study explains that white sharks have behaved similarly in other regions of the globe.
In North America, for example, at the Southeast Farallon Islands great white sharks have been recorded fleeing from hunting areas after killer whales 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 stated.