There is always a bigger fish.
A new study by the Monterey Bay Aquarium found that even great white sharks, one of the most formidable predators in the ocean, have something to fear.
According to the research, which also included research partners from Stanford University, Point Blue Conservation Science and Montana State University and published in this month’s Nature’s Scientific Reports, found that great white sharks will abandon their feeding grounds in the Farallon Islands National Wildlife Refuge during the presence of orcas.
“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.
The researchers used tracking data from tagged great white sharks along with sighting data of killer whales to conclusively show how white sharks clear out of the area when the orcas show up. In every case examined by the researchers, white sharks fled the island when orcas arrived and didn’t return there until the following season. Electronic tags showed all white sharks began vacating the area within minutes following brief visits from orcas.
“On average we document around 40 elephant seal predation events by white sharks at Southeast Farallon Island each season,” Monterey Bay Aquarium scientist Scot Anderson said. “After orcas show up, we don’t see a single shark and there are no more kills.”
It was unclear whether it was the possibility of becoming prey for the orcas or they left because of the competition for the primary food source, however, researchers did observe four cases of killer whales preying on the sharks in the area during the study.
“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.”