On May 20—just before the Memorial Day holiday that draws thousands of boaters and beachgoers to the water—the research firm Ocearch announced that it had tracked a great white shark deep in Long Island Sound for the first time. A tracking device, the researchers said, showed the nearly 10-foot-long animal swimming off the coast of Greenwich, Connecticut.
What happened next was the kind of Jaws-meets-Sharknado media frenzy that makes marine researchers cringe. CBS News gave beachgoers plenty to fuel their imaginations, reporting that the animal weighed more than 500 pounds. The harbormaster in Greenwich confirmed for The Connecticut Post that it would be unusual for a great white to be so far west in the sound, adding that people likely had nothing to worry about, because the shark was “probably well fed.” ABC News covered the story on its “World News Tonight” television program, calling the ping from the tracking device “an ominous alert.” Putting a fine point on the media message, NBC’s “Today Show” urged beachgoers to “stay safe this Memorial Day.”
The reporting was shared endlessly on social media sites including Facebook and Twitter, reaching thousands more people. Then, just 12 hours later, the story started to change. All of a sudden, researchers said, the same shark was being tracked off the southern shore of Long Island, suggesting that it had never even entered Long Island Sound at all. The confusion, experts say, is one that’s born of two types of technology. First, there’s shark-tracking technology, which, in this case, is rarely perfect. And second, there’s media technology, which, in this case, spread questionable information faster than Jaws movie actor Roy Scheider could say, “You’re gonna need a bigger boat.”
Many kinds of marine researchers use different types of devices to track sharks nowadays. The tracking technology used with this particular shark is called SPOT, which stands for Smart Position and Temperature. It’s placed on the shark’s dorsal fin, and it only transmits the shark’s position to satellites when the fin emerges from the water. The pings that researchers see, therefore, are occasional at best, making this type of technology ideal for tracking long-term migration patterns as sharks move across great distances.
“Think of how the pitch of a siren changes as a police car or ambulance passes,” says Megan Winton, a research scientist at the Atlantic White Shark Conservancy in Chatham, Massachusetts. “Now think about how accurate your estimate of the position of that police car would be if you had no visual and were basing it solely on the sound. You’d probably be in the ballpark but with a good amount of error.”
Greg Metzger, chief field coordinator for the shark research and education program at the South Fork Natural History Museum in Bridgehampton, New York, says that all kinds of human judgment calls go along with assessing the already imperfect information that pings from a SPOT tag. For instance, researchers also look at weather conditions, mathematical models and more to try and determine how valid the data coming from the ping actually is. “If there’s seaweed or something attached to the antenna, that cuts down the signal’s ability,” he says. “Heavy cloud cover can disrupt the signal. How many satellites are in the area above that tag to lock onto it, that matters—the more satellites, the more accurate the location of the tag.”
What happened in this case, he says, is that researchers saw two or three pings come in close to Greenwich within a few hours’ time, adding legitimacy to the incoming data. There wasn’t just a random, one-off ping in a location where researchers would not expect a great white to be. But then, within a dozen hours, another ping showed up far enough away from Greenwich that the shark couldn’t have gotten there in the same amount of time, giving researchers a reason to doubt the data that previously had seemed trustworthy. “Ocearch had a call, and they put the word out, then more information came in,” Metzger says. “More pings came off the shark, and that’s all.”
If not for the spread of the story online and in the media, Metzger says, the apparently false information would not have concerned researchers. “If it’s off a few miles here or there, for the question of migration, it’s not really that big of a deal,” he says. “It averages out during the course of the four or five years that those types of tags typically give information.”
Other kinds of shark-tagging technology, are now capable of estimating locations via GPS, which makes the devices as accurate as a chartplotter on a boat. Metzger’s team, for instance, is using a device called a pop-off satellite tag to determine how baby white sharks, less than a year old, are using Long Island Sound as a nursery.
“That records the depth and temperature the shark is at, about every 20 seconds for 28 days, so we’re getting very, very accurate, fine-scale movements,” he says. “Then the tag pops off and floats to the surface so we can find it. Otherwise, it emails data it has collected for the last 28 days.”
That type of research on baby sharks is the first of its kind, he says, adding that while tagging technology continues to improve, our understanding of how the animals use Long Island Sound is in some ways still nascent.
“We want to know where they are, how long are they here, when they leave Long Island waters and when they come back,” Metzger says of the babies. “There really isn’t anything known about the basic day in the life of a shark.”
This article originally appeared in the August 2019 issue.
