UM's Shark Guru

UM's Shark Guru

From hammerheads to great whites, University of Miami researcher Neil Hammerschlag is a dedicated specialist on just about all things sharks.
From hammerheads to great whites, University of Miami researcher Neil Hammerschlag is a dedicated specialist on just about all things sharks.
UM News

The five massive tiger sharks had been ripping apart the drifting whale carcass for hours, cutting into its flesh with their razor-sharp teeth.

When University of Miami shark researcher Neil Hammerschlag heard about the feeding frenzy a couple of months ago, he thought: Perhaps this is a chance to learn something new about Galeocerdo cuvier. So he and two of his team members raced south on US Highway 1 in his Subaru Crosstrek, chartered a dive boat when they arrived in Key Largo, and headed out into the Gulf Stream.

After two hours of searching, they finally spotted them: Five of the biggest male tiger sharks Hammerschlag had ever seen, each of them taking turns ripping away chunks of the floating remains.

“I’m going in,” said Hammerschlag, slipping into a wet suit.

No use in trying to talk him out of it, his team members knew. That would have been like asking Armstrong not take his “giant leap for mankind,” or Amundsen not to make the treacherous trek to the South Pole. Like all great explorers, Hammerschlag has curiosity in his blood. “Sharks feeding on a whale carcass—that’s something rarely witnessed in nature, and there was no way I was going to miss that opportunity,” said the research associate professor at UM’s Rosenstiel School of Marine and Atmospheric Science, where he runs the Shark Research and Conservation (SRC) Program.

So he dove in, swimming to within only a few yards of the creatures, one of them as long as an SUV. “For the most part, they ignored me,” Hammerschlag recalled. “But whenever I’d get too close to the carcass, they would swim aggressively toward me, as if to say, ‘Back off.’ ” Which he did.

“That carcass was like a Las Vegas all-you-can-eat buffet, and there was enough blood and guts in the water to attract predatory fish from all over,” Hammerschlag said. “But aside from the five tiger sharks, there were no other sharks in the area. That told me they must have been preventing other sharks from coming into the area, maybe by communicating in some ways we just don’t know about yet.”

If anyone can figure out the answer, it is Hammerschlag. From blacktips to bulls, great hammerheads to great whites, and whitetips to tigers, he’s been studying sharks for nearly two decades, first becoming captivated by the predators more than 17 years ago, when, as a University of Toronto undergraduate, he interned with a group of California researchers tagging sharks in the Pacific. “Ever since then, I’ve never looked back,” he said.

Indeed, he’s come a long way since the days of his youth when he would strap an empty 2-liter soft drink bottle on his back, jump into the family pool, and pretend he was scuba diving.

Today, Hammerschlag is an accomplished shark researcher who’s had his fair share of airtime on the big networks. He’s been featured on NBC's Today, the syndicated entertainment television newsmagazine Entertainment Tonight, and the National Geographic Channel.

This Monday at 8 p.m. on Discovery, he’ll go shark tagging with New England Patriots tight end Rob Gronkowski on “Monster Tag,” making it the third season in a row that Hammerschlag’s been featured on the network’s widely popular Shark Week series.

As part of the weeklong series, which is celebrating its 30th season, Hammerschlag’s work will also take center stage on “Shark Tank Meets Shark Week” (July 25 at 9 p.m.), featuring powerhouse Manhattan real estate broker Barbara Corcoran, and “Tiger Shark Invasion” (July 26 at 10 p.m.), in which he and cinematographer Joe Romeiro travel to the Galapagos to meet ups with researcher Alex Hearn to locate and study a population of tiger sharks that appears to have increased over the last 10 years in one of the world’s oldest marine ecosystems.

The Hollywood-style exposure hasn’t spoiled Hammerschlag. He’s still a big Pearl Jam fan, traveling as far away as Europe to see his favorite rock band perform, and he hasn’t abandoned his favorite hobby—taking underwater photos of what else—sharks.

If anything, the limelight has actually been beneficial in some respects, he admits. Famous figures like English magnate Richard Branson and Olympic champion swimmer Michael Phelps, who have both gone on shark tagging expeditions with Hammerschlag, help raise awareness about the plight and importance of sharks, attracting a new breed of fans to the study of these animals.

“Shark Week is a powerful tool,” notes the UM researcher. “That’s how many people learn about sharks. A few years ago, Discovery decided to integrate more science into their shows to make them more educational and realistic, and that’s a great thing.”

Above all, it’s the research that’s most important to Hammerschlag.

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Hooked on Sharks

A native South African who earned his Ph.D. in marine biology and fisheries at the University of Miami Rosenstiel School of Marine and Atmospheric Science in 2009, Neil Hammerschlag knows a lot about sharks. He’s made several appearances on Discovery Channel’s Shark Week series.

Feeding Frenzy

Neil Hammerschlag, research associate professor at the University of Miami Rosenstiel School of Marine and Atmospheric Science, where he runs the Shark Research and Conservation (SRC) Program, filmed tiger sharks feeding on a whale carcass off the Florida Keys in May 2018.

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Shark Tagging

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Shark Tagging

Apex Predators 

After Hammerschlag graduated from the University of Toronto, his fascination with sharks led him to Florida, where he earned a master of science in marine biology from Nova Southeastern University. He then enrolled at UM’s Rosenstiel School, earning a Ph.D. in marine biology and fisheries in 2009. Now, as the founding director of SRC, he and his team of graduate students and staff study and tag sharks year-round, tracking their movements to better understand the biology, ecology and behavior of a super predator that swam the world’s oceans long before dinosaurs even roamed the Earth.

His message to the world: We should be afraid for sharks, not of them. Many of them are apex predators, he explains, and as such, they help maintain healthy marine ecosystems, preying on fish below them in the food chain and helping to keep prey populations in check. 

Yet many shark populations around the world are in decline, with some species threatened and others endangered. Nearly 20 percent of all known species of sharks face extinction, their numbers dwindling primarily as a result of overfishing but also due to climate change and the loss of their habitats.

By some estimates, close to 100 million sharks are killed each year, the majority targeted for their meat, liver oil, and cartilage, but mostly for their fins, which are chopped off and used to make shark fin soup, a delicacy in East Asia.

Hammerschlag’s exhaustive research is a way to shed new light on these fascinating creatures to ultimately save them. Among his investigations: He and his students have determined the home range of great hammerhead sharks, a threatened species, off Florida coastlines, showing how much of their habitat falls within waters where they are protected and waters where they are vulnerable to fishing.

He and his team of other scientists have employed the same ultrasound imaging technology used on expectant mothers to study pregnant tiger sharks, performing sonograms on the sharks to determine their reproductive cycles.

In collaboration with neurologists at UM’s Miller School of Medicine, he found high concentrations of toxins linked to neurodegenerative diseases like Alzheimer’s in the fins and muscles of 10 species of sharks, a study that suggests that restricting the consumption of sharks could have positive health benefits for consumers and for shark conservation.

“In a new study, we're even studying how urbanization—pollution, noise, light, water quality, those things that are coming from land in a big urban center like Miami—is affecting the behavior and health of sharks,” said Hammerschlag.

Tagged for Survival

It all starts in the field, aboard a vessel in the waters of the Atlantic and Gulf of Mexico, where the South African-born researcher and his students deploy drum lines—unmanned aquatic traps with baited hooks—to lure and safely capture sharks. Once a shark is hooked, the animal is carefully secured to a platform. Then, in a process akin to a NASCAR pit stop, Hammerschlag and his students spring into action, with each team member performing a different task, from inserting a hose in the shark’s jaws to help it breathe to measuring its length, taking blood and tissue samples, and attaching a tag to its dorsal fin. With a push, they send the animal on its way. All told, the process takes less than five minutes.

Hammerschlag has logged hundreds of hours on such trips. But he can’t set sail on all of them. “I try to go on as many as I can, but I have to write scientific papers, advise and teach students, inform the public about our work and write the grants that fund our research,” he said.

His students, who he has meticulously trained, lead many of the tagging expeditions. “Everyone’s got a stake in it,” Hammerschlag explains. “Our team will come up with a plan, and these amazing students implement it. I guide them through it, but they’re in the trenches doing most of the tagging.”

It could be a nurse shark or a tiger shark, a bull or a great hammerhead. Whatever the species, the tags will eventually tell their story—from simple identification tags that provide the location of a shark’s capture and release, to electronic acoustic tags that emit an ultrasonic ping, allowing hydrophones to record a shark’s location and how much time they spend in a certain area.

When SRC researchers want to know where the sharks are going, they attach sophisticated satellite tracking devices to their dorsal fins, tracking the predators in real time.

While the lab and blood workups on these animals may seem less appealing than the tagging expeditions, the hard science being done under the microscope is just as important. Using blood samples, some of Hammerschlag’s students are studying the immunology of sharks, looking for ways to assess their health in the natural marine habitat.

Pregnancy Exam for Jaws

Using the same imaging technology as that employed by medical professionals on pregnant women, Neil Hammerschlag at the University of Miami has teamed with scientists from the University of New England to capture detailed images of the reproductive organs of female tiger sharks, revealing the presence of pups in the womb without having to kill the sharks to conduct such research.

Shark Declines Can Lead to Change in Reef Fish Shapes

The researchers found that at Scott Reefs, where shark populations have declined, the eyes of fishes that are normally prey for sharks were on average up to 46 percent smaller compared to the same sized fish of the same species on reefs at the Rowley Shoals where shark populations are healthy.

Study Finds Seals Stressed Out by Sharks

The researchers found that seals exhibited high stress levels when the risk of great white shark attack was high, such as at locations where and when the seals were under risk of unpredictable and lethal attack from great whites.

Saving Sharks 

He’s brought the world of shark research to inner-city youth, taking hundreds of elementary and high school students on shark tagging trips each year. SRC has even founded a program—Females in the Natural Sciences or F.I.N.S.—that provides girls with hands-on experience in marine science. “We want to inspire the next generation of scientists, conservationists and problem-solvers,” Hammerschlag said.

His research helps inform policymakers who enact the laws that protect sharks.

“There’s not a blanket policy that works best for all sharks in all scenarios,” he said. “Our goal is to triage and figure out which species and populations are in need of the most help, and to learn enough about the biology and ecology of sharks to generate the most effective conservation-management decisions.

“It’s been great to see different laws enacted while we’ve been doing this research,” he continues. “But there’s still more work to be done.”