Conservation & Science

Our commitment to science: white shark research

Monterey Bay Aquarium has since its inception affirmed that we are a science-driven organization, and that science underpins all of our public policy, research and education programs. That’s why we’re a partner with the national March for Science, a series of more than 500 events around the world on April 22.

As part of our commitment to the scientific process, our white shark research team works to understand and conserve these vital ocean predators. In advance of the March for Science, we’re taking a look at many of our scientific initiatives—in research, policy and education. Here’s a look at some of our recent white shark science highlights.

Annual Field Research

Every fall for the last decade, the Aquarium’s white shark research team has headed out to the Farallon Islands off the coast of San Francisco to tag, track, and identify white sharks as they feed on elephant seals and sea lions. The team observes behavior, captures underwater video, and deploys electronic tracking tags that relay information about white shark migrations and habitat preferences. When the team returns to the lab, they combine and analyze all these data to better understand white shark populations and their role in maintaining the healthy ocean ecosystems that ultimately support all life on Earth.

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Dispatch from the Farallones: White shark family portraits

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.


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Approaching the Farallones.

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.

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A whale fluke surfaces near our sailboat as we near the Farallon Islands.

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.

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The spooky science of shark mummies

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.

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Location of shark dump site in Baja California, Mexico.

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.

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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.”

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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.

New research: Steep decline for shark attack rate in California

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.

Salvador Jorgensen and colleagues tagging adult white sharks off the Farallon Islands near San Francisco.
Salvador Jorgensen and colleagues tagging adult white sharks off the Farallon Islands near San Francisco.

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.

Infographic courtesy Stoked School of Surf, South Africa

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.

Where and when you choose to surf , swim or scuba dive in California can dramatically reduce your risk.
Where and when you choose to surf , swim or scuba dive in California can dramatically reduce your risk.

“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.

Cynthia McKelvey

Reference:

Feretti, F., Jorgensen, S. Chapple, T.,K, De Leo, G., Micheli, F. 2015. Reconciling predator conservation with public safety Frontiers in Ecology and the Environment. (Vol. 13, Issue 6)

 

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