There’re 440 known shark species on the planet. Some, such as the whale shark, grow to the size of a school bus. Others, like catsharks, are no bigger than a kitten. Certain sharks prefer the warmer Gulf of Mexico, and others seek out the chilly Pacific. As apex predators, some subsist on large predatory fish like grouper and tuna. Others live on plankton. There’s the great white with its serrated, blade‑like teeth, the blacktip with its eponymous fin marking and the hammerhead with its, well, hammer‑shaped head.
But on a commercial fishing boat — where a shark’s head, tail and fins are typically amputated from its body — distinguishing one shark species from another gets tricky, and potentially illegal as regulations prohibit certain threatened and endangered species from being caught and mandate that each fin on board correspond with its carcass.
Sounds simple enough, except shark fin soup is an expensive delicacy in Hong Kong and mainland China, and responsible for the death of tens of millions of sharks a year. It is illegal to harvest the three largest species of hammerhead sharks in Florida waters, but their fins are a prized commodity. Through the years this has enticed some crooked fishing vessels to cut the fins off the endangered creatures and dump their still-alive bodies at sea, where they could drown or bleed to death. To skirt enforcement, fishing vessels would catch a legal species, like a blacktip, hack off its fin and Frankenstein the butchered body parts to pass as one whole shark. It was left to law enforcement to solve this bloody maritime jigsaw puzzle.
That’s where Dr. Mahmood Shivji came in. In the late 1990s, the charismatic marine geneticist and conservation biologist took a position at Nova Southeastern University and moved to South Florida from the Pacific Northwest. He read about the shark body part dilemma in the newspaper. He had never researched sharks, but it sparked an idea that went on to change the trajectory of his career, and in the past two decades the application of his work has saved countless sharks in the process.
“I never worked with sharks before, but I’m a geneticist,” says Shivji, who now leads both the Guy Harvey Research Institute and Save Our Seas Shark Research Center at Nova Southeastern University. “And DNA is the same from a shark to a coconut tree to a human.”
A headless and finless bull shark might not look very different from a headless and finless great white. But on a molecular level, each shark species has its own DNA fingerprint, which Shivji set out to find. These key forensic genetic markers are what differentiate a coconut tree from a human, and a hammerhead fin from a blacktip shark carcass. Shivji published his findings in 2001, and the National Oceanic and Atmospheric Administration quickly adopted Shivji’s technique. They even called on the professor to write affidavits so NOAA’s Office of Law Enforcement could build cases against anyone caught with illegal shark species. The work would eventually become unnecessary in the US thanks to new regulations requiring all harvested sharks be brought to land with their fins intact. But for a time, Shivji’s team did detective work.
“They used to call it CSI: Shark Week,” Shivji jokes in his office overlooking the water of Port Everglades at NSU’s Halmos College of Natural Science and Oceanography in Dania Beach. “We’ve branched out into a lot of things since then, but that rapid DNA forensic method for identifying shark body parts is what we built our reputation on.”
It’s All In The Genes
Dun Dun. DUN DUN! Jaws was released in 1975, and it’s hard to bring up sharks without cuing the ominous theme song ever since. Sharks have been depicted as deadly beasts, lurking with their triangular fins poking out of the dark water as they wait to devour the nearest human. In reality, roughly six people die from shark attacks a year. In 2018, there were four fatalities in the world. Many shark researchers are quick to point out that falling coconuts kill 150 people a year.
Being at the top of the food chain, sharks maintain the overall health of the marine ecosystem by removing weak and sick creatures. Without them, larger predatory fish like grouper take over. They feed on herbivores, and the absence of herbivores can lead to algal blooms that cause coral reef die-offs.
And yet, even armed with those facts, Shivji still seems nervous to acknowledge the abundance of sharks off South Florida’s shores: Lemon sharks, nurse sharks, sandbar sharks, blacktip sharks, great hammerhead sharks. He pauses, and it’s clear that he’s worried not that the sharks’ existence will harm any humans but that knowledge of their existence might lead humans to harm sharks.
“Many people are afraid to go in the water because they think they’re going to be eaten by a shark. The media has a lot to do with this because they hype it on TV,” Shivji says. “There are a lot of sharks right here that people don’t even know about because they don’t see them, but they’re there.”
Shivji is considered one of the leading shark researchers in the world. The Guy Harvey Research Institute (GHRI), which he leads, is a scientific research organization established in 1999 to understand and save the world’s fish resources and biodiversity. It’s a collaboration between NSU and the renowned marine life artist whose work is popularly reproduced on shirts, hats and even mousepads. In 2005, NSU even changed its mascot from the Knights to the Sharks after consulting with Shivji. “They went with mako sharks – they’re the fastest shark in the ocean,” Shivi says. “There are mako sharks in South Florida but because it’s warmer here they tend to be much deeper.”
A few years later, Shivji’s forensic marine work caught more media attention when he tested the DNA of fish served at local restaurants and found that red snapper, grouper and white tuna are commonly mislabeled. “Cooking the fish degrades its DNA,” Shivji says. “I’d wipe off any sauce, put the little piece of meat in Ziploc bags and store it on ice.” For homework, Shivji instructed his students to order seafood and bring their leftovers to class to test its DNA to see if it confirmed the menu description. A report released later found that fish is mislabeled about a third of the time in South Florida.
In 2009, Save Our Seas Shark Research Center (SOSSRC) was established at NSU to focus on study and conservation of sharks and rays worldwide. Shivji was appointed director. In tandem with GHRI, Shivji’s team has grown to nine scientists and researchers, and they’ve traveled as far away as Brazil, Ireland and New Zealand for their work. Several years later, the marine campus at Dr. Von D. Mizell-Eula Johnson State Park in Dania Beach, located directly at the entrance of the Port Everglades channel, received an upgrade with a new state-of-the-art five-story building. Today, GHRI and SOSSRC are located on the third floor with panoramic waterfront views and what’s believed to be the largest private collection of Guy Harvey art on its walls. “Someone once made the joke that we went from the outhouse to the penthouse,” Shivji says.
Earlier this year Shivji celebrated another big win: mapping the first great white shark genome in a project co-led with Cornell University biologist Michael Stanhope. Sharks evolved from the rest of the animal kingdom 400 million years ago, and decoding the great white’s genome was a massive undertaking and years in the making. Great whites have 41 pairs of chromosomes compared to humans’ 23. The project will help conservation biologists understand great whites and other shark species that are in steep decline.
But Shivji points also to stunning clues for great whites’ most curious abilities: their resilience to heal from serious wounds in a matter of months and knack for fending off cancer, a trait known as genome stability that suppresses tumors and repairs mutated DNA.
With more research, Shivji’s confident that studying shark genes can one day save human lives. He pauses. “There’s one important thing: we are absolutely not saying that if you eat sharks, you’ll heal faster or beat cancer…It’d be like saying that if you eat sharks you’ll swim faster.”
Shark Tales
Classes have let up for summer, and Shivji’s lab on the third floor is practically empty on a recent Friday afternoon except for one researcher in a white lab coat studying samples. The space is flooded with natural light, and boats can be seen bobbing on the water in the distance. An enormous gray shark fin rests on the counter beside a serpentine cookie-cutter shark preserved in what looks like a pickle jar filled with formaldehyde.
Shivji walks to a flat screen monitor beaming his non-genetic venture: shark tracking. For the past seven years, Shivji and his team have been clipping satellite tags on close to 300 sharks, including makos, tiger, whitetip, hammerhead and even whale sharks all over the world from the Yucatan Peninsula to Western Australia to Bermuda and up the Atlantic coast. They’re studying their migration ecology.
“We wanted to know how far do these things travel, where do they go, when do they go, why do they go,” Shivji says. They were shocked to see that makos can travel more than 9,000 miles in a year, the equivalent of two roundtrip jaunts between New York City and Los Angeles.
To promote human-shark relations, Shivji and his team take schoolchildren on field trips out on their boats to tag sharks with them. There’s even an option to sponsor a shark on their live, public site, which explains why some of the sharks are named “Advanced Roofing,” “Jiffy Lube” and “St. Marys.” The latter is actually a primary school in Ohio, and St Marys the mako met an untimely end after being captured (legally) by fishermen in 2015.
“It’s sad because the kids at that school were following him, but it becomes a life lesson,” NSU spokesperson Joe Donzelli says. “All of a sudden the shark’s trajectory makes a straight line and the tag is blinking and reporting from shore.”
But Shivji and his team couldn’t help but notice that a large portion of their tagged sharks were being captured by fishermen. When they crunched the numbers, they found that twelve of the 40 makos they had tagged over three years had been harvested – roughly 30 percent and 10 times higher than the fishery mortality estimates. In March, NOAA updated its regulations prohibiting the capture of mako sharks of a certain size to prevent overfishing.
“It was another very fast practical application of the science,” Shivji says, “that led to shark conservation.”
In 2000, President Clinton signed the Shark Finning Prohibition Act into law, which made it illegal to hack a fin off a shark and release it back into the water were it could drown or bleed to death. But soon after the mako overfishing findings, another researcher set out to find exactly how many sharks were being harvested in the shark fin trade and the results were higher than anyone expected: up to 73 million a year.
It led Oceana, an ocean conservation and advocacy organization, to fight to ban the sale and trade of shark fins imported and exported through the United States. Earlier this year, the Shark Fin Sales Elimination Act was introduced into Congress. So far, it’s received bipartisan support.
“It is currently legal to catch a shark and sell its fin,” says Cat Uden, a Broward-based Oceana campaign organizer. “But with shark species’ declining numbers, this isn’t sustainable if the sale of fins is not just legal but lucrative.”
Like Shivji, Uden doesn’t like to recount her shark tales to prevent any fearmongering. But she’s surfed beside hammerheads in Hawaii, swam with leopard sharks in California and taken her kids swimming with sharks in the Bahamas. She’s even taught her children to simply leave alone the nurse sharks they sometimes encounter when they go swimming in South Florida.
“They are more afraid of us than we are of them, and rightfully so; we’re a danger to them,” Uden says. “Instead of feeling that fear, I get so excited every time I see a shark.”
Shivji understands that not everybody is going to love sharks. But the more he learns about them, the more usefulness and potential he sees – from reef preservation to perhaps even treatments for cancer. More than anything, he hopes people realize that it’s more valuable to conserve sharks than to consume them. “Even,” he says, “if just for purely selfish reasons.”
