Conservation & Science

For white sharks, an oasis, not a desert

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.

White sharks tagged along the California coast guided researchers to the offshore waters where they spend half the year. Photo by Steven K. Webster/Monterey Bay Aquarium

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.”

Researchers spent a month at the White Shark Café aboard the Schmidt Ocean Institute’s R/V Falkor. Photo courtesy Schmidt Ocean Institute

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.

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New insights to help young white sharks survive

What can scientists studying white sharks learn from an expert on mountain lions? As it turns out, quite a lot.

Monterey Bay Aquarium and its research colleagues have been tagging juvenile white sharks in southern California since 2002. Now they’ve gained new insights into white shark survival from those data tags. Photo courtesy Steve McNicholas

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.

At the heart of the effort was the work of lead author John Benson. Before taking his current role as a professor at the University of Nebraska, John was a post-doctoral researcher at the Monterey Bay Aquarium, working with senior research scientist Sal Jorgensen.

Young white shark on exhibit at Monterey Bay Aquarium.

“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. Read more…

Voyage to the White Shark Café

For nearly 20 years, researchers from Monterey Bay Aquarium and Stanford University have fitted electronic tracking tags on adult white sharks each fall and winter along the California coast around San Francisco Bay. Each year, the tags documented a consistent migration by the sharks to a region more than 1,200 miles offshore—halfway to Hawaii—that’s been considered an oceanic desert. They dubbed it the White Shark Café, guessing that opportunities to feed and to mate might be the draw.

Now a team of scientists will spend a month at the Café in a month-long expedition to learn why the sharks make an epic annual migration to such a distant and seemingly uninviting location. The multi-disciplinary team is bringing an impressive complement of sophisticated oceanographic equipment, from undersea robots and submersibles to windsurfing drones that will search signs of sharks and their possible prey.

Funded by the Schmidt Ocean institute (SOI), the team is led by Stanford University Professor Barbara Block and includes marine biologists and oceanographers from Stanford University, Monterey Bay Aquarium, Monterey Bay Aquarium Research Institute (MBARI), the University of Delaware, and NOAA’s Office of Ocean Exploration and Research.  They are traveling aboard the SOI research vessel Falkor and set sail from Honolulu on April 20. They will return to port in San Diego on May 19.

Unraveling a mystery

We’ve studied these sharks for nearly 20 years, and they’ve told us consistently that the White Shark Café is a really important place in the ocean—but we’ve never known why,” said Dr. Salvador Jorgensen, a senior research scientist and shark research lead at Monterey Bay Aquarium.

Sophisticated oceanographic monitoring tools like these Saildrones will collect data to document the presence of white sharks and their prey species in the cafe. Photo courtesy Schmidt Ocean Institute.

By documenting the biology, chemistry and physical conditions in the region—a swath of the Pacific Ocean the size of Colorado—the researchers hope to understand what makes the Café an annual offshore hot spot for one of the ocean’s most charismatic predators. Read more…

Camera to crack a white shark mystery

The idea seemed like a long shot: Build a video camera that could attach to a great white shark for months at a time, withstand ocean depths of more than 3,000 feet, and sense the shark’s movements to selectively capture footage of its behavior.

But Monterey Bay Aquarium Senior Research Scientist Salvador Jorgensen, a white shark expert, thought it might have a chance if he joined forces with the talented minds at the Monterey Bay Aquarium Research Institute (MBARI).

“Some of the engineering team said it was an impossible job,” MBARI Engineer Thom Maughan recalls with a smile. “But I’m attracted to those opportunities.”

So Thom and Sal teamed up on a high-tech mission: to capture video footage of great white sharks in their most mysterious habitat.

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Shark fins, unique as fingerprints

To most of us, all white sharks look similar: strong, elegant and powerful. But not to Aquarium Senior Research Scientist Dr. Salvador Jorgensen.

“In order to tell them apart, we like to think of something descriptive to call them: Middle-notch, or Split-fin, or Rooster,” Sal says. “There’s one that looks like a profile of Jay Leno. We have a shark called Hitchcock. We have one called Elvis.”

Jay-Leno-Shark
When you stare at shark fins all day, you might start to see things – like Jay Leno’s profile.

He pulls up a photo of a  dorsal fin—the characteristic, triangular fin on a white shark’s back that features prominently in movies like Jaws—and compares the negative space at the tip to a profile of Jay Leno. The two are an uncanny match.

Like fingerprints and retinas are unique to each person, a dorsal fin is unique to each white shark. Each fin has scars, pockets and notches.

Sal and a number of colleagues from Stanford and Montana State University are taking advantage of these fin fingerprints to identify the same sharks as they return to Central California year after year.

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In the belly of the beast: a shark tag’s travels

“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.

The internal tag was wrapped in whale blubber so the shark would swallow it. Photo courtesy Sal Jorgensen.
The internal tag was wrapped in whale blubber so the shark would swallow it. Data were later calibrated to align with the orientation of the shark’s body. Photo and illustration courtesy Sal Jorgensen.

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.

White shark swallows a feeding tag. Photo courtesy Sal Jorgensen.
White shark swallows a feeding tag. Photo courtesy Sal Jorgensen.

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.

– Cynthia McKelvey

Citation: Jorgensen SJ, Gleiss AC, Kanive PE, Chapple TK, Anderson SD, Ezcurra JM, Brandt WT, Block BA. (2015). “In the belly of the beast: resolving stomach tag data link to temperature, acceleration and feeding in white sharks (Carcharodon carcharias).” Journal of Animal Biotelemetry, December 2015, 3:52.

Unlikely landing for white shark tag

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.

Data tag washed up on a Monterey Bay area beach 10 months after it was fitted on a juvenile white shark off the southern California coast.
This data tag washed up on a Monterey Bay area beach 10 months after it was fitted on a juvenile white shark off the southern California coast.

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.

An aquarium team scoured the beach north of the Pajaro River. They found the shark tag near the high tide line.
An aquarium team scoured the beach north of the Pajaro River. They found the shark tag near the high tide line.

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.

The shark was collected and tagged on November 6, 2014 in Santa Monica Bay by our research partners with the Southern California Marine Institute and the California State University Long Beach Shark Lab. At the time, it was about 6.5 feet in length and weighed 146 pounds. Based on its size, they estimated it to be just over a year old.

Juvenile white shark spotted in Monterey Bay the week of September 7.
Juvenile white shark spotted in Monterey Bay the week of September 7.

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.

Learn more about our shark research program.

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