When orcas and white sharks cross paths, only one can prevail as the true apex predator. New research from the Monterey Bay Aquarium published in Nature Scientific Reports details these rare, sometimes brutal encounters — and their ecological implications.
It’s a study decades in the making because observations of the two creatures interacting is a rarity.
Scot Anderson, a white shark expert and seasonal researcher for the Aquarium, still remembers one such run-in more than 20 years ago near the Farallon Islands, a short boat ride west of downtown San Francisco.
“The first time it happened was kind of shocking to everybody,” Scot says. “Before we had seen anything like that, people would ask, who’s the baddest predator?”
The first scorecard came on October 4, 1997, when orcas killed and partially ate a white shark within view of a whale-watching boat. Scot was heading out from nearby Bolinas when he heard what was happening over the radio.
Monterey Bay and surrounding waters are prime habitat for white sharks. The same adult white sharks visit this part California annually over decades, mostly during fall and early winter. Farther south, from Santa Barbara to Central Baja, white shark babies, or pups, typically spend their first years in warmer “nursery” waters.
What’s new and surprising, though, is that in recent years a seasonal group of younger white sharks has established itself within sight of the beaches at the north end of Monterey Bay. Is this new cohort taking up residence as a result of warming ocean conditions? And why are the sharks aggregating in one portion of the bay?
This spring, a diverse team of ocean scientists headed to the middle of the Pacific Ocean, seeking to explore the vast and mysterious home of one of the world’s top ocean predators: the white shark.
Guided by the sharks and their need for a steady supply of food, the researchers sailed into the heart of what was once deemed an oceanic “desert.” They discovered that the open Pacific, particularly an expanse dubbed the White Shark Café, teems with abundant and unusual life forms—organisms that may help explain the fascinating behaviors of white sharks on the high seas.
“The Café is far from the desert it was thought to be,” says Aquarium research scientist Dr. Sal Jorgensen. “It is home to an abundance of life that satellite imaging is not detecting. In fact, for white sharks, it is more of an oasis.”
The White Shark Voyage team embarked from Honolulu for a month-long journey aboard the Schmidt Ocean Institute’s R/V Falkor and traveled east to waters halfway between Hawaii and Mexico.
Headed by principal scientist Dr. Barbara Block of Stanford University, the research team aboard the Falkor included marine biologists, engineers and oceanographers from Monterey Bay Aquarium, Stanford, Monterey Bay Aquarium Research Institute (MBARI), University of Delaware, NOAA, Montana State University and ocean tech innovator Saildrone.
While no one knew what they’d find, everyone hoped to gather insights about what might be driving the behaviors of white sharks, and what role this offshore habitat plays in the lives of these apex ocean predators.
What can scientists studying white sharks learn from an expert on mountain lions? As it turns out, quite a lot.
Such a collaboration is on display in new research published in the Journal of Applied Ecology. Models that estimate survival rates for top predators on land, according to the study, can also work in the ocean. The research also revealed important safeguards that can help protect white sharks while they’re young and vulnerable.
“We always learn things from adjacent fields,” says Sal, who specializes in white sharks, and who coauthored the paper along with six others. “John made his name studying mountain lions in Southern California.”
John’s past work also involved black bears in Louisiana, panthers in Florida, wolves and coyotes in Canada, and moose and their various predators in Alaska. After so much experience on land, John saw working with Sal at the aquarium as a chance to—as the saying goes—get his feet wet. Continue reading New insights to help young white sharks survive
Monterey Bay Aquarium’s white shark tagging team recently made its annual visit to the Farallon Islands outside San Francisco Bay. The goal: to continue its long-term efforts to monitor a genetically distinct population of adult white sharks, which gathers at the islands each fall to gorge on seals and sea lions.
During the trip, team members took photos to identify individual sharks by their dorsal fin patterns, collected tissue samples for genetic research, and attached electronic tags to study these majestic ocean predators. Presley Adamson, associate producer and editor for the Aquarium’s film team, reports back on his experiences in the field.
It’s been two hours since we lost sight of the Golden Gate Bridge and, with it, any sign of civilization. Dr. Salvador Jorgensen, senior research scientist for Monterey Bay Aquarium; and Scot Anderson, a pioneering white shark expert and seasonal researcher for the Aquarium, are somehow sleeping through the relentless rocking and rolling of our sailboat. I’m too excited to sleep.
Choppy waves have kept us stuck on shore for six straight days. Today, the waters are finally calm enough for us to cross the 25 miles of open ocean between San Francisco and the Farallon Islands.
The Farallones are technically part of the City of San Francisco, but we won’t find any subdivisions or grocery stores here. The islands, their surrounding waters, and their plant and animal inhabitants are protected in the Farallon National Wildlife Refuge, within the Greater Farallones National Marine Sanctuary.
More elephant seals and sea lions than people visit the Farallones. The abundance of blubbery pinnipeds attracts some of the largest white sharks in the world, who hang around the islands looking for a meal.
Sal and Scot have brought me along to document this year’s research season. I’m armed with six cameras that need to be set up before we get to the Farallones. I also need to put on foul-weather gear—boots, life jacket, raincoat, and other gear to stay warm and dry. But I’m distracted by a pod of humpback whales next to our boat, showing off their giant flukes as they go about their own morning commute.
I can just start to make out a lone pinnacle emerging from the sea. We’re almost there.
John O’Sullivan, the Aquarium’s Director of Collections, was in Mexico on a mission. A young white shark equipped with an electronic tag had traveled over 650 nautical miles south from its release point in Monterey Bay, and the tag had popped off somewhere along the central coast of Baja California. The tag contained a complete data set documenting the shark’s movements and physiology since its release, and John aimed to recover it.
Instead his guide, a local fisherman, led John to a shark graveyard.
A grisly grimace
Sometimes, commercial and sport fishermen accidentally ensnare juvenile white sharks off the coasts of California and Mexico. But locals in some communities consider it bad luck to discard the unmarketable parts, such as the heads, back into the ocean. Instead, they deposit these shark parts at dump sites in the Mexican desert.
In central Baja, just north of Guerrero Negro, John and a team of local Mexicans encountered hundreds of shark heads, in various stages of decay. Some were fresh; others were rotting. Some had skin that was dry and well-preserved—in other words, mummified—in this arid location.
Many of us would turn away from that gruesome sight. But John and his colleagues looked into the mouths of the shark-head mummies and saw an opportunity.
“If you were to put a Fitbit on a white shark, where would you put it?” asks Monterey Bay Aquarium research scientist Salvador Jorgensen. “The answer is in its stomach.”
Jorgensen and his colleagues are trying to learn where and when white sharks feed by using an electronic tracking device called a “Daily Diary” that works like the activity-logging Fitbit. Where a Fitbit tracks steps, the Daily Diary tracks tail beats. It also monitors changes in temperature and pressure.
Sharks are apex predators that occupy the top of the food web—but their might does not always keep them safe from human activity. And without sharks to keep prey animal populations in check, the food web could crumble. Knowing when and where sharks feed will help researchers identify places that need protection so that white sharks can have plenty of food to eat in peace.
A challenging project
Devices like the Daily Diary are a popular way to study wild animals, Jorgensen says. But attaching them to an ocean animal is challenging. It’s relatively easy to place an accelerometer on the leg of a sedated cheetah, but a shark is a whole other kettle of fish. So instead, Jorgensen and his team have the shark do what it does best: eat.
In their latest study, published in the Journal of Animal Biotelemetry, the team – which includes researchers from the Aquarium, Stanford University and Montana State University – used the internal Daily Diary attached to a pop-up archival transmitter (PAT) tag to record feeding behavior in wild and captive sharks. In the wild, researchers lured white sharks to a skiff using a seal-shaped decoy. They wrapped the two internal tags in whale blubber—like putting medicine in a dog treat—and fed it to the shark.
Getting the tag back is easier than you’d think. Like owls, sharks eat their food and later regurgitate solid and indigestible materials. When the tag is regurgitated, it floats to the surface and pings its location to the research team.
What the data reveal
The stored data tell the story of shark feeding behavior. Sudden bursts of acceleration indicate that a shark is swimming fast to ambush its prey. If the shark is successful, the acceleration is followed by a measurable increase in stomach temperature.
Of course, that knowledge has to come from data stored on the physical tag, which isn’t always easy to retrieve from the ocean – especially if someone beats you to it.
One time, researcher Paul Kanive got a favorite shark, nicknamed “Scar Girl”, to swallow the tag. But right after he returned from his sampling trip, Kanive got a call from Jorgensen saying that Scar Girl’s tag had surfaced north of San Francisco, in Tomales Bay, and the signal was heading toward the boat ramp at Nick’s Cove. Kanive raced over and asked everyone on the dock if they had, by chance, retrieved any bright orange devices in the water.
‘Find something orange?’
Kanive noticed a man putting a kayak on his truck and asked him if he had found anything orange. “And he kind of stopped and smiled,” Kanive said. “He was like, ‘Ah, I knew that thing would get me in trouble!’”
Kanive said the kayaker was happy that he was able to help the team out but, “He was blown away that I was there asking him if he found something that nobody saw him find.” After he retrieved the tag, Kanive was able to get Scar Girl to swallow it once more.
For the first time since we started tagging juvenile white sharks in southern California more than a decade ago, we’ve retrieved one of the tags in Monterey Bay.
The tag spent 10 months on a young shark before it popped free over Labor Day weekend and washed ashore just north of the Pajaro River, in Santa Cruz County. Several aquarium staff members went beachcombing and found the data-rich tag on Sunday, near the high tide line.
The tag showed up in an area where a number of young white sharks have been spotted in recent weeks. Several were featured on Big Blue Live when they were caught on camera by airborne film crews. Our white shark research scientist Sal Jorgensen photographed the sharks this week as well.
Our research team speculates that unseasonably warm sea temperatures drew the young sharks far north of their usual haunts off southern California and the Baja Peninsula.
No other juvenile white shark has carried a data tag this long, so our white shark team is eager to download the information stored on the tag. They’ll learn where the shark journeyed over the past 10 months, and the water temperatures it favored.
We and our colleagues have tagged 93 sharks since we began tagging juveniles in 2002. Data from the tagged animals show a seasonal migration pattern between southern California and Mexico, with the sharks appearing to seek out warmer waters.
This is the first time young white sharks have been seen in such numbers in Monterey Bay since the last El Niño event in 1997.
Here’s a video showing some of the young white sharks in the bay’s warmer waters this summer.
It’s summer beachgoing season and with the recent spate of shark bite reports in the Carolinas, sharks are more top of mind than ever. But are shark attacks really on the rise?
Research published today by Stanford University’s Hopkins Marine Station and the Monterey Bay Aquarium shows that, indeed, the overall number of shark bites on the California coast is climbing gradually every year. But there’s a catch. Since 1950, the annual rate of shark attacks has actually decreased – and fairly dramatically.
Using data from the Global Shark Attack File, Aquarium shark biologist Sal Jorgensen and his Stanford colleagues discovered a surprising story. The research team noticed that even though the number of attacks was rising, they weren’t keeping pace with the tripling of California’s coastal population – from 7 million people in 1950 to 21 million coastal residents by 2013.
The numbers of surfers, scuba divers and swimmers rose at much faster rates than the overall population. So when the team weighted their data to reflect the number of ocean users, they found that the likelihood or rate of an individual being bit by a white shark dropped substantially – by 91 percent between 1959 and 2013.
“This shows that the goals of public safety and conserving the ocean wilderness, intact with top predators, are actually compatible.” Sal says. “Our results also suggest that attacks could be further reduced by modifying when and where we get in the ocean.”
Using a statistical model, the team was able to determine the most and least risky times and locations for shark attacks. According to their data, October through November – when sharks are feeding on seals along the coast – are the most likely times for attacks to occur. March through May are relatively safer times to be in the water – when most white sharks are far offshore at the mysterious White Shark Café.
The authors noted that beachgoers and water enthusiasts face many greater perils than a shark attack. Hospitalizations from drowning and scuba-related decompression sickness occur at much higher rates than those from shark bites.
“Our disproportionate fear of shark attacks is amplified by a lack of having control when we enter the ocean wilderness,” notes Sal, an avid surfer himself. “This type of data can give people the ability to have more control and minimize their risk.”
For instance, the results showed it’s 1,566 times safer to surf between San Diego and Los Angeles in March, compared with surfing between October and November in Mendocino County.
Making these types of informed choices would be far more effective at increasing public safety than culling, the research finds. In Australia, officials have tried to reduce public risk by killing white sharks in a large culling program – a tragic and uninformed approach. In fact, culling sharks is ineffective.
“These programs often serve more to reassure people rather than effectively increase beach safety,” says Francesco Ferretti, a postdoctoral research fellow at Hopkins Marine Station and the study’s lead author.
Though culls are meant to target white sharks, other shark species are often killed as well. Because of the importance of all shark species to maintaining the balance of the food web, culls can dramatically disrupt the ecosystem. And they’re extremely costly. The cull in western Australia is slated to cost $22 million.
Francesco says the money could be more wisely used to promote research and awareness of sharks, and to come up with more effective solutions to keep people from encountering sharks.
In California, white shark attack rates have declined so much that the researchers wonder if perhaps the numbers reflect a decrease in the shark population over the last half decade. An alternative possibility is that as populations of marine mammals – adult white sharks’ favorite prey – have bounced back, the sharks have relocated closer to their rookeries.
Marine mammals, especially elephant seals, tend to congregate on island beaches far away from those used by people. The Aquarium’s ongoing research with Hopkins colleagues may provide some answers in the near future.