Conservation & Science

New kids on the block

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.

The cohort of young white sharks close to popular Santa Cruz County beaches has sparked Monterey Bay Aquarium researchers to investigate what’s drawn them to the area. Photo © Giancarlo Thomae Photography

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?

That’s what Monterey Bay Aquarium research scientist Dr. Sal Jorgensen and his colleagues hope to determine in the coming months.

Read more…

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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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.

Read more…

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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