If Chief Martin Brody would have had an orca on him, Jaws would have been a much shorter movie.
Image credits: John Boscarino.
A new study published in Scientific Reports finds that even the king of the oceans has something that will send them scurrying. The report has found that great white sharks will make themselves scarce when orcas, often referred to as killer whales, have been found in the area. While reports of orcas attacking great whites have been sparsely recorded, this is the first evidence of great whites actively avoiding the whales.
“When confronted by orcas, white sharks will immediately vacate their preferred hunting ground and will not return for up to a year, even though the orcas are only passing through,” said Dr. Salvador Jorgensen, senior research scientist at Monterey Bay Aquarium and lead author of the study.
Researchers documented four encounters between the top predators at Southeast Farallon Island in the Greater Farallones National Marine Sanctuary, off San Francisco, California. They monitored data from 2006 to 2013 of 165 tagged great whites and compiled 27 years of seal, orca and shark surveys at the Farallones. Within minutes of meeting the orcas, the sharks would hightail it to safer waters. Predator on predator encounters — dubbed ‘lateral interactions’ — have been well documented on land, however, those interactions are not as well understood in the sea.
“We don’t typically think about how fear and risk aversion might play a role in shaping where large predators hunt and how that influences ocean ecosystems,” Jorgensen said. “It turns out these risk effects are very strong even for large predators like white sharks—strong enough to redirect their hunting activity to less preferred but safer areas.”
The research team — which included Jorgensen and Monterey Bay Aquarium scientist Scot Anderson, and research partners from Stanford University, Point Blue Conservation Science and Montana State University — found that in every case examined, the great whites fled the island once orcas arrived at the scene. They didn’t reemerge until the following season. Previous research has shown that killer whales kind of have a thing for shark livers, which is probably one reason sharks opt for the flight option in lieu of the fight.
That behavior was also found to have a positive effect on the elephant seal colonies, as the data found four to seven times fewer predation events during those periods the sharks left. While some orcas will eat elephant seals, the locals have only been found to feed on fish.
“On average we document around 40 elephant seal predation events by white sharks at Southeast Farallon Island each season,” said Monterey Bay Aquarium scientist Scot Anderson. “After orcas show up, we don’t see a single shark and there are no more kills. These are huge white sharks. Some are over 18 feet long and they usually rule the roost here.”
I guess at the end of the day, Free Willy beats Jaws.
