Emperors of the Deep

So when Mary Lee suddenly vanished, people naturally feared the worst. Dropping off the map wasn’t like her. It certainly wasn’t the kind of behavior expected by her growing legion of fans or her handlers. Either she had decided to go offline for a few weeks or—as seemed more likely as June turned to July—Mary Lee wasn’t ever coming back.

I first heard about Mary Lee, and the growing frenzy surrounding her, from Greg Skomal, a senior fisheries biologist at the Massachusetts Division of Marine Fisheries and head of the Massachusetts Shark Research Program. Skomal, who’s been studying great white sharks in Cape Cod since the Reagan administration, couldn’t stop talking about her. I can’t say I blamed him. As he made abundantly clear over the course of our conversations, it isn’t every day you get to track in real time a 16-foot, 3,456-pound great white, certainly not in the waters of the Atlantic.

“The great white shark is still really an open book,” Skomal told me in his office at the Shark Research Program, where he and his team examine the migratory patterns and social behavior of great whites. “When you turn on the television and see white sharks doing incredible things, typically it’s filmed in the Pacific and Indian Oceans. Scientists for decades have been studying this species in those areas. White sharks in the Atlantic have always lagged behind in terms of what we know about its biology, its natural history, its ecology. We didn’t have any of the white shark hot spots you see in other oceans.”

That all changed around 2004, according to Skomal, when the Northeast’s previously imperiled seal population started to flourish three decades after the Marine Mammal Protection Act of 1972 prohibited local fishermen from killing them to protect fish stocks. Once the seals returned to Cape Cod, so did the white shark, the seals’ natural predator. The return of white sharks provided scientists like Skomal with an unprecedented opportunity to study them. For the first time, they had regular access to white sharks in the Atlantic Ocean. “If you can find the species you’re trying to study,” Skomal said, “you can study it.”

And if you can study the species, you can start to figure out its biology, its behavior, and, over time, the size of its population—previously unknown data sets that help scientists get a better understanding of the species’ overall health and, as Skomal and others are starting to figure out, how the health of the Atlantic is directly related to the well-being of white sharks in its waters.

Skomal was part of the team that caught Mary Lee off the coast of Cape Cod in September 2012. Under the direction of OCEARCH founder Chris Fischer, the former Emmy Award–winning host of ESPN’s Offshore Adventures program, Skomal and a group of researchers tagged Mary Lee’s dorsal fin—the great white’s telltale peak—with a Smart Position and Temperature Transmitting Tag. SPOT, as the tag is also known, allowed OCEARCH to track Mary Lee’s movements and, in a technological twist, broadcast her whereabouts to the general public in real time across Twitter, Facebook, and the organization’s other social media platforms.

Because collecting data from free-swimming sharks is next to impossible, the catch-and-release work of OCEARCH is helpful. If scientists are ever going to understand these apex predators and their role in maintaining the world’s oceans, they need to examine them up close. Watching the operation unfold is a thing of beauty. In the video OCEARCH released of Mary Lee’s capture, Fischer spots the shark while chumming the waters in a skiff. Once he and his crew catch it, Fischer radios ahead to Skomal, who’s waiting a few miles away on the OCEARCH, a floating at-sea laboratory. “We are all green here,” Fischer tells him, calm and collected amid the growing excitement. “We are a full go. Big, big, big mature female shark. Definitely a five-plus-meter fish.”[1]

Towing the shark, Fischer steers the skiff toward the OCEARCH and docks the shark into a floating pen, a 75,000-pound capacity hydraulic platform that is slowly raised out of the water, until the pen looks like a wood-paneled pool deck extending off the massive vessel. Then, with the precision of a NASCAR pit crew, Fischer and his team get to work. To lessen the shark’s nervousness, one man covers the shark’s head with a large towel. He then inserts a large hose into the shark’s mouth, providing the captured shark with a continuous flow of fresh seawater so it can breathe in the open air. While that man caters to the shark, others frantically start tagging her, measuring and sexing, drawing blood samples, and performing a quick muscle biopsy to identify reproductive habits and, according to the OCEARCH website, assess organic and inorganic contaminants. One man, who I assume drew the short straw, scraped bacteria and other marine parasites from the shark’s teeth. Before releasing the shark safely back into the sea, Fischer christened his great white Mary Lee, after his mother. “I didn’t know if I was ever going to have the opportunity to name another shark,” he later admitted during a press conference.[2]

The entire operation—catch, tag, and release—took less than fifteen minutes, but those fifteen minutes ultimately produced more than five years’ worth of new research about great whites, the ocean’s most mysterious and most misunderstood inhabitant.

“What we’ve done, for the first time in history, is establish a proven method of capturing the ocean’s giants and releasing them alive,” said Fischer. “And, in between, giving the leading scientists fifteen minutes of access to use all of the latest technology and to do all of the research projects they’ve ever dreamed of.”[3]

To achieve Fischer’s stated goal of providing a brighter future for the white sharks, OCEARCH and their collaborators first need to learn the fundamental pieces of the white sharks’ life. If scientists are to preserve the great whites, they need to understand their behavior, biology, reproduction, and range movements. This list is by no means exhaustive. One important place to start is with the population size and the health status of the great whites on the East Coast. Another important area to explore is where the sharks mate, give birth, and grow up as juveniles. To this day, no one has ever witnessed a great white giving birth. If a scientist can determine exactly where white sharks mate and mature, for instance, they can petition the government to protect those maritime areas.

OCEARCH has worked with scientists from different organizations, and their ongoing tagging program has catalogued hundreds of sharks, which are added to OCEARCH’s open-source database to aid researchers in their work.

Still, as we enter this golden age of shark research, Skomal was quick to remind me, “There’s a lot for us to learn.”

Fischer told the Associated Press in 2013 that he expected Mary Lee to be more of an offshore fish, taking advantage of the Atlantic’s bountiful schools and, potentially, hanging out in the North Atlantic right whale’s birthing habitat off the Carolinas. Instead, Mary Lee hugged the East Coast, traveling from Cape Cod to Charleston, then up and down the Southeast, swimming between Jacksonville, Florida, and Wilmington, North Carolina, before heading around Cape Hatteras, toward New York, a few miles offshore from Times Square. While Mary Lee didn’t pinpoint potential birthing sites, her path did help to confirm what scientists knew about the distribution of white sharks off the eastern coast of the country. Before she could spill any more secrets, however, Mary Lee went offline. The loss of Mary Lee was a setback, but the best approach as far as Fischer, Skomal, and everyone else was concerned was to keep tagging as many white sharks as they could and, as a result, uncover as many of the species’s hidden secrets as possible.

On a subsequent expedition, Skomal and his team pinned another white shark—this one named Luci—with a sophisticated pop-up satellite archival transmitting tag, which over time collected data about the shark, including the depths of its dives. Figuring out a shark’s migratory pattern was useful, but piecing together a shark’s movements as it ventures nearly a mile below the surface of the ocean would help scientists figure out how deep a shark can dive and, once it’s down there, what sharks might do at those depths. After receiving via satellite Luci’s data, Skomal and his team were able to piece together, meter by meter, one of Luci’s most spectacular dives as she cruised along the East Coast of the United States. Skomal established her position at 600 feet below the ocean’s surface. While there is plenty of sunlight at the surface, light quickly fades as the depth slowly absorbs it. Continuing the descent, Luci freely exited the sunlit zone, speeding through the enveloping darkness past 660 feet, where only 1 percent of the light penetrates the increasing density.

In 2014, a scuba diver named Ahmed Abdel Gabr, a former member of the Egyptian army, set the Guinness World Record for the deepest scuba dive. Having spent four years training, he successfully dove 1,000 feet under the Red Sea, proving that humans—or at least one with seventeen years’ experience as a diving instructor, three canisters of oxygen strapped to his back, and a support team in tow—could survive a deep-sea immersion. Abdel Gabr’s descent took twelve full minutes, while Luci blew past this depth in a matter of seconds.

Past 1,000 feet, water pressure begins to reach staggering proportions. One atmosphere at sea level equals 14.6 pounds of pressure per square inch, the same as the weight of the earth’s atmosphere. This means that, on land, each square inch of your body is subjected to a force of 14.6 pounds. Water pressure increases about 1 atmosphere every 33 feet of depth, which at 1,000 feet, translates to 30 atmospheres, or roughly the equivalent of one large, 450-pound, adult pig squatting on every square inch of your body. To withstand water pressure at this depth, German engineers reinforced the hulls of U-boats, which allowed them to dive beyond 1,000 feet, but even these engineering marvels couldn’t survive a dive beyond 1,200 feet. Like early explorers venturing across the Atlantic and Pacific Oceans, Skomal and his team were discovering something entirely new, something truly groundbreaking, a high point in shark research.

A deep dive creates problems for many animals. For humans, high blood nitrogen pressures can exert a narcotic effect, known as “nitrogen narcosis,” which during ascent may lead to nitrogen bubble formation, a phenomenon known as “the bends.” Great whites avoid this problem at this depth because they don’t have lungs or swim bladders.

Well beneath the sunlit zone, which ends at 660 feet, Luci breached the middle of the twilight zone at 1,750 feet. This bewitching area of the ocean (660 to 3,300 feet) is too dark for photosynthesis. Many underwater creatures live in the dim light here during the day but travel up the water column to hunt at night in the sunlit zone. Sharks are highly suited to this area because, like lions, they can see in the dark, thanks to the tapetum lucidum, a layer of tissue behind the retina that reflects light through the retina a second time, increasing the light available to the eye’s photoreceptors. Because Luci’s eyes can take in light even in near darkness, she would have still been able to attack unsuspecting prey, if she were so inclined. But she wasn’t finished diving. Luci easily beat the maximum depth of a nuclear-powered submarine (1,750 feet) and, 950 feet later, eclipsed the height of the Burj Khalifa in Dubai, the world’s tallest building.

At 3,000 feet, Luci entered the ocean’s dark zone. No light can penetrate this depth. No plants can grow there. The only source of food is the “snow” of waste from above. To the surprise—and celebration—of Skomal and his team, Luci bottomed out at 3,700 feet, where she was surrounded by total darkness except for the occasional bioluminescence of nearby fish, jellyfish, and crustaceans, which flashed in the water like lightning in the pitch-black sky.[4]

Luci is not the only shark star with such diving capabilities. In New Zealand, the National Institute of Water and Atmospheric Research (NIWA) tagged a 16-foot-long shark they named Shack, which set the world’s record for the deepest known dive by a great white shark at 3,900 feet. According to NIWA, Shack “regularly … deep dives between 3,200 and 3,900 feet while crossing the Pacific Ocean.”[5]

Nature has designed great whites like Luci, Shack, and others to routinely dive to great depths around the world. They inhabit one of the most inhospitable places on the planet. The pressure at this level is staggering, roughly the weight of a grand piano on every square inch of a great white’s body. At this depth, Luci was the only living thing with solid mass; every other creature was gelatinous and had strange, translucent appendages. Temperatures at 3,700 feet are equally unfriendly at 35° to 39°F, which Luci combated by generating her own body heat. While Skomal and his team studied the mechanisms of Luci’s singular descent, they remained mystified about the reason for the dive. The Marine Conservation Science Institute’s Michael Domeier has theorized that, at these depths, sharks like Luci are likely hunting a giant squid, a mysterious, deep-ocean dweller. Most squid live at the surface and are only 2 feet long, but at 3,000 feet, they grow twenty times bigger. At these depths, squid, worms, and sea crabs grow to monstrous sizes because of a phenomenon known as “abyssal gigantism,” a condition scientists link to either the deep-sea environment’s higher atmospheric pressure or its colder temperatures. For years, people doubted giant squid really existed. Then some began washing up on beaches around the world. A squid measuring 30 feet in length beached in Galicia, Spain, while other recent discoveries proved that female and male giant squid can grow as long as 43 and 33 feet, respectively. Before Skomal confirmed great whites can dive to this depth, the only known predators of giant squid were sperm whales. But as Luci bottomed out, it wasn’t too hard to imagine great whites and giant squid waging epic battles at the bottom of the ocean floor.

ONE OF THE GREATEST IRONIES ABOUT WHITE SHARKS IS THAT they aren’t white—or at least not entirely. Only their underbelly is white. This design is shrewd, because in deep-sea water the shark’s blue-white countershading camouflages them when pursuing prey.

Great whites are one of the largest carnivorous sharks in the ocean; however, they are only sixth in overall size compared to other sharks, a fact that belies the notion of the great white as a killing leviathan. The largest sharks, which are harmless to humans, belong to the filter feeder category—the whale, the basking, and the megamouth sharks, all of whom are larger than the great white. Like great whites, the Pacific sleeper and Greenland sharks are carnivorous but larger, according to Greg Skomal. Unlike many species, where males are bigger than females, female white sharks like Mary Lee are larger than their male counterparts, which on average measure between 11 and 13 feet and weigh between 1,500 and 1,700 pounds. Mature females grow to 15 or 16 feet and can weigh up to 2,500 pounds. While males can easily reach 17 feet, it is not unusual for a female shark to grow to 20 feet in length and weigh 4,300 pounds, equal to the length and weight of an adult giraffe, as difficult as that is to imagine. A white shark caught in Cuba in 1945 measured 21 feet in length and weighed a staggering 7,300 pounds, or 3.5 tons, a weight equal to six adult grizzly bears. The reason female white sharks are larger than males is simple: as Skomal told me, females need considerable strength and abdominal space to carry their pups during the white shark’s long gestation period, all while continuing to hunt. It takes longer for a white shark to develop in utero than it does a human, mainly because once they are born, shark pups are on their own. Unlike dolphins and orca whales, which protect their babies, white sharks leave their pups to fend for themselves. The great white pups eat what they can catch, which in their infancy is fish. As white sharks mature, they start hunting seals and other larger mammals.

“[Pregnant white sharks] are older animals,” Skomal explained. “They’re in their twenties and thirties when they reproduce. And they’re not capable of reproducing until they hit those sizes and those ages. When an angler removes a young, or small, great white shark from the ocean, it has a significant impact on the population because that shark probably hasn’t lived long enough to breed.” The population replacement rate for the white shark is extremely low, which makes the species vulnerable to exploitation. “They’re maturing at a late age and only giving birth to a handful of young, most likely, every two to three years. We have to be particularly conscious of this when it comes to sustainability, conservation, and management of the species.”

While there is still no reliable data about the world’s total great white population, scientists believe that the total number is dropping, largely because of overfishing and other environmental factors. White sharks are currently listed as vulnerable, a tick above endangered, on the International Union for Conservation of Nature’s Red List of Threatened Species.

The white shark’s vulnerability belies the popular misconception of the species as bloodthirsty man-eaters. “When people think of white sharks,” Skomal told me, “they think all kinds of things. Most of them are fairly negative, which came out of Jaws. Hollywood has done a very good job of scaring the hell out of people.”

The nearly five-decade-long counterattack against sharks is not just the result of the cultural impact of Jaws. It is also the result of the rapid expansion of the commercial fishing industry during the 1980s. These developments endanger the species and, in the process, upset the delicate balance of the marine ecosystem.

A fear of sharks has led people to seek the thrill of catching them. But what I have found out about the great white is extraordinary. In sharks and in life, fear is often the absence of knowledge. “The more people know about these animals,” Skomal said, “the more likely they are to revere them as opposed to fear them. The more we’re learning about sharks, the more we’re learning that they’re an integral part of the marine ecosystem.” Fischer and Skomal and an entire generation of marine biologists and conservationists have dedicated their careers to trying to change the public’s perception of sharks, specifically great whites, as underwater monsters.

Like most teenagers of his generation, Skomal discovered marine life from TV shows like The Undersea World of Jacques Cousteau and National Geographic, which brought color images of sharks and other underwater wonders to living rooms around the world for the very first time. But what really impacted Skomal were his family vacations to the Caribbean, where he fell in love with the ocean, mesmerized at an impressionable age by coral reefs and the variegated fish species he saw scuttling about their natural environment.

“When I was, like, twelve, thirteen years old, I wanted to study sharks, but I figured by the time I got old enough to do it, it would all be done,” he said. “How naive was I?”

Later, after resolving to learn everything he could about the ocean, Skomal enrolled at the University of Rhode Island, where he earned his bachelor’s and master’s degrees. He later returned to school to earn his PhD at Boston University. While searching for a full-time researching job, he volunteered at a federal laboratory. Surrounded by field scientists with years of experience, Skomal conducted scientific investigations, developing in the process an unshakable passion for great whites. In 1987, he landed a full-time job as a senior fisheries biologist at the Massachusetts Division of Marine Fisheries, where he quickly realized that most of the scientific knowledge about great whites emerged from hot spots in the Pacific and Indian Oceans. Fortunately, his career coincided with the return of great whites to the northeastern Atlantic Ocean, once the seal population returned. “I was at the right place at the right time,” Skomal told me. The entire Atlantic Ocean was suddenly his to explore and research, uncontested. “Many white sharks come up to Cape Cod in the summertime, and simply move in the wintertime down to the coasts of Florida and Georgia and South Carolina. But then we have a component of the population that wanders the Atlantic, and those are most intriguing to me. You know, not just the coastal migratory pattern, but the ones moving out into the central part of the Atlantic, where they’re diving to great depths.”

Like Fischer, Skomal has a nose for finding great whites. To date, he and his team have tagged and tracked more than 150 great whites and have identified approximately 350. In a 26-foot skiff, he regularly patrols the waters off Cape Cod’s Monomoy Island, an 8-mile-long run of sand extending southwest from Chatham. The island is a popular congregating spot for seals. Often, Skomal films these encounters. From his boat, he looks out for the great white’s unmistakable shadow underwater: a dark mass moving through the green water. When he sees a shark, he approaches the prow and plunges a tag into the base of the passing shark’s dorsal fin. No worse for wear, the shark swims on, unbothered.

As Skomal described it, hunting for sharks sounds routine and uneventful, like swimming laps in a pool. But it isn’t always this easy or stress-free. Once, trying to get a close-up of the shark’s face to help identify it, he attached his GoPro on a pole and plunged it into the water. He had done this scores of times but on this occasion, an 11-foot female went right for the camera. “It kept coming and then opened its mouth and bit it,” he said, calling the shark’s action exploratory, rather than predatory. If it had been the latter, he reminded me, the shark would have destroyed the camera and, in all probability, pulled Skomal into the water during their brief tug-of-war.

Skomal added that this shark was not one of the 150 sharks in the area that were already tagged by his team for research. He and his team will now review the video to look at her markings and determine if she’s brand new to the area or if she is one of the 350 sharks his team has tracked previously. These experiences and the research information that come out of this tagging program have helped to answer a number of questions about great whites, including their life expectancy, which has confounded scientists for years.

Previous studies concluded that great whites live into their twenties and thirties. However, as scientists continue to collect more information, such estimates are proving problematic. Schoolchildren know that as trees grow, they lay down rings on an annual basis. Each ring represents a year. Sharks similarly lay down band pairs of rings on their vertebrae, which is thought to be on an annual basis. While this trait was known in small to medium-large white sharks in the northwestern Atlantic, what was not known was that, after maturity, the largest sharks may experience a change in the rate of vertebral material deposition. Another difficulty scientists encountered while trying to determine a shark’s age was that some bands become too thin to read accurately.

The best scientific method to determine the life expectancy of great whites is radiocarbon dating. This well-known method uses the properties of radiocarbon (carbon-14), a radioactive isotope of carbon, to determine the age of an object. But where could scientists find the white sharks for the test? It just so happened that a lab in Narragansett, Rhode Island, contained the largest collection of vertebrae samples from white sharks caught in the northwestern Atlantic Ocean from 1967 to 2010. Using this material and the National Ocean Sciences Accelerator Mass Spectrometry facility at Woods Hole Oceanographic Institution, scientists were able to determine that great white sharks can live to over seventy years,[6] which means that great whites are alive today that, as pups, heard the sound of US depth charges attacking Nazi submarines in World War II. Based on the data they collected from Mary Lee, Skomal estimated that she is in her early thirties, a woman in her prime. Because she likely has another forty years in her, if she were still online, she would have helped scientists identify her preferred breeding ground and pup nursery, which could have provided Skomal and other scientists with invaluable insights to assist with management of the species.