Great White Sharks Are Being Scared From Their Habitat by Just Two Predators

The great white shark is the most terrifying sea creature of all time.

The great white is considered to be one of the ocean's top predators due to its sleek body, sharp teeth, and reputation for enjoying human flesh. That's true, but there's more to it than that.

Scientists have documented that the sharks have become very rare off the coast of South Africa. Humans were initially blamed for the disappearance.

According to new research, the true culprit is a pair of orcas that hunt the sharks and eat their valuable organs.

The fishing town of Gansbaai on the South African coast used to be a mecca for shark-spotters because it was so heavily populated with the sharks. The shark's presence has been decreasing over the last few years.

The hallmark of an orca attack is when seven great white sharks wash up on the shore without their hearts or lungs. The wounds on the sharks are different from those on the orcas. Scientists think that the pair are responsible for many more great white deaths that haven't been found.

The presence of orcas can cause great white sharks to leave the area. If an orca makes an appearance in the area, great whites will leave the preferred hunting waters off the coast of San Francisco.

A team of scientists led by Alison Towner have shown that orcas are the reason sharks are avoiding certain areas.

Towner said that great white sharks didn't show up for weeks or months after the orca attack.

In response to increased lion presence, we are seeing a large-scale avoidance strategy used by wild dogs in the Serengeti. The longer the great white sharks stay away, the better.

The team tracked 14 sharks that had been tagged as they fled the area when orcas were present. Great white sharks are not seen as often in several bays.

This is significant. Since record-keeping began, there have only been two times when great white sharks have been absent for a week or more in the area. Researchers said that the new absences are unprecedented. They're changing the environment.

In the absence of great white sharks, copper sharks are moving in. The orcas are hunting the coppers instead of preying on the sharks. The researchers said that they are doing so with the skill of predator who have hunted large sharks.

With no great white sharks limiting Cape fur seal behavior, the seals can predate African penguins, or compete for the small pelagic fish they eat. "That's a top-down impact, we also have'bottom up' trophic pressures from extensive removal of abalone, which graze the kelp forests these species are all connected through."

Although this is a hypothesis for now, the impact of orcas removing sharks is likely to be much wider-reaching.

There are reasons why orcas might be hunting sharks. The sharks use their huge, plump, and full of fats and oil to fuel their epic migratory journeys. It's not clear how the orcas figured this out or why they would seek the shark livers as a source of nutrition.

Scientists theorize that some orcas may be adapting to preferentially hunt sharks in response to declining numbers of their preferred prey. The added pressure of an efficient predator is a cause for concern.

Towner said that the orcas are targeting subadult great white sharks, which can further impact an already vulnerable shark population.

Increased vigilance using citizen science, as well as continued tracking studies, will aid in collecting more information on how these predations may impact the long-term ecological balance in these complexes.

The research was published in a journal.