When you think orcas could not be more impressive, they get even better. New evidence shows that these whales are really good at scare the most feared beast out of the sea. Yes. The killer whales knocked the great white shark out of its "predator apex" throne.
A team of marine scientists has found that large white sharks (Carcharodon carcharias) will become extremely scarce whenever they detect the presence of orcas (Orca orcinus).
"When confronted by killer whales, white sharks will vacate their preferred hunting grounds and will not return for up to a year, even though orcas are just passing by," said marine ecologist Salvador Jorgensen of the Monterey Bay Aquarium.
The team collected data from two sources: the comings and goings of 165 large white sharks mapped between 2006 and 2013; and 27 years of population data for killer whales, sharks, and seals collected by Point Blue Conservation Science on the southeast of Farallon Island off the coast of San Francisco.
The team also documented four encounters between large white sharks and killer whales in Greater Farallones National Marine Sanctuary, which they were able to analyze in relation to the other data.
The data showed that whenever orcas appeared in the area – as at all times – the sharks left quickly to the left and remained out until next season. They would be off in minutes, even when the killer whales stayed for less than an hour.
And there was a surprising beneficiary: sea elephants (Mirounga distressing) that inhabit the coast and are preyed upon by the great white sharks.
"On average, we have documented about 40 predatory events of elephant seal by white sharks in southeast Farallon Island every season," said marine biologist Scot Anderson of the Monterey Bay Aquarium. "After the orcas appear, we do not see a single shark and there are no more deaths."
It is also known that transitional orcas eat the elephant seals, but these visiting whales only appear infrequently. Resident killer whales feed on fish.
The sharks have not always gone far. Sometimes they only moved at a safe distance along the coast, where they were close to different colonies of elephant seals. At times, however, they were headed into the middle of the Pacific Ocean, the region dubbed White Shark Cafe.
These are also not tiny sharks. Some of them measure more than 5.5 meters (18 feet) from nose to tail, and are probably too accustomed to making their own way wherever they go. But 5.5 meters are on the small side of killer whales, which can attack whales much larger than this, so they are unlikely to be easily pushed.
In addition, orcas were observed attacking large white sharks around the world, including near the Farallon Islands. The reason for this is not yet known, but the dead sharks on orcas that are on dry land (one of them is at the top of the page) do not have their livers – their delicious livers rich in oil and full of vitamins.
If sharks are instinctively avoiding predators that can eviscerate them so easily, or if the transients in the past have bullied the sharks away from the source of elephant seals food is still a stranger.
"I think this demonstrates how food chains are not always linear," Jorgensen said.
"The so-called side interactions between top predators are well known on land, but they are much harder to document in the ocean, and because this happens infrequently, it may take a little longer to fully understand the dynamics."
The research was published in the journal Scientific Reports.