Researchers are working to tag and study young sand tiger sharks that come to Massachusetts waters year after year.
Beneath the waves of Boston Harbor, hidden in murky inlets and marshes, the start of a marine conservation success story is quietly unfolding. It’s a story of diligence and disappointment, of scalpels and sutures and blood, of long bouts of calm and short bursts of frenetic energy. It’s a story that spans decades and many miles of shoreline.
On a stunning late August afternoon, researchers from the Anderson Cabot Center for Ocean Life at the New England Aquarium set out on a small boat to write the next chapter in that story. Their mission is to implant tracking devices in juvenile sand tiger sharks. Their mood is buoyant, perhaps even giddy.
That atmosphere is largely the product of Ryan Knotek, the shark researcher leading the tagging efforts. Most days, his work involves sitting at his computer writing proposals, he explains. Days like this are much better.
Ryan Knotek and Emily Jones reel in a juvenile sand tiger shark near the Squantum Marshes in Quincy. – Madison Lucchesi/Boston.com
Knotek is a fisherman at heart whose longstanding obsession with sharks traces back to viewing Discovery Channel’s “Shark Week” at a formative age. He is in his element out on the water, dicing up frozen fish to use as bait, casting lines, deftly tiptoeing on the side of the vessel as he maneuvers around other passengers. Knotek spent the night before this outing perusing fishing forums and practicing how to tie sutures at his kitchen table. He only gets around four hours of sleep a night, but one would never know it. There is a cooler on board the boat well stocked with energy drinks.
Knotek steers toward the Squantum Marshes of Quincy Bay. This unassuming section of water is a sweet spot, he says. Young sand tigers are all over Boston Harbor and nearby areas from mid-July through September, but this is the only place where Knotek knows he can reliably catch the sharks.
Sand tigers live in coastal waters all over the world, but decades of overfishing caused population numbers to decline by around 75% by the early ’90s. That, coupled with the fact that sand tigers have one of the lowest reproductive rates among all sharks, put the species in serious danger.
They are still considered critically endangered, but a few decades of conservation efforts in some areas, like the East Coast of the U.S., are starting to show signs of success. One of the clearest signs of a population that is beginning to bounce back is the presence of juvenile sand tigers north of Cape Cod, according to Knotek. A little over 10 years ago, researchers began finding and tagging them in Duxbury Bay. After fishermen began reporting their presence in Boston Harbor, scientists like Knotek took an increased interest in proving that the young sharks are frequenting those waters as well.
“We basically fished all over the harbor trying to find these things. It was a lot of trial and error,” Knotek says.
After a few years’ hiatus due to the COVID pandemic, Knotek and others have spent the late summer and early fall months tagging sand tigers in Boston Harbor. The goal, he says, is to gather enough data so that NOAA Fisheries designates it as a “Habitat Area of Particular Concern.” Knotek hopes to tag 40 to 50 sharks before submitting a proposal to NOAA. Around 25 have been tagged so far. The most he’s ever caught in a single day is four.
Juvenile sand tiger sharks move north to areas like Boston Harbor during the late summer months to find food and avoid predators. – Madison Lucchesi/Boston.com
Adult sand tigers spend most of their time farther south, off the coast of the Carolinas. Juveniles, which are only four or five feet long, are at risk of being eaten by the adults. They follow schools of Atlantic menhaden up the coast and around the tip of Cape Cod, taking advantage of the Cape’s natural barrier until water temperatures drop and they must travel south again.
Even after studying sharks for his entire life, Knotek is still amazed at the ability of the young sand tigers to find extremely specific feeding grounds year after year.
“These sharks make me feel like I have zero intelligence sometimes,” he says. “These sharks are one or two years old and travel thousands of miles back to this one very small part of Wollaston Bay… If I didn’t have Google Maps, I’d be lost in my neighborhood.”
Shark surgery
Not long after anchoring near the Squantum Marshes, one of the five fishing rods set up around the boat suddenly jitters. The line goes taut, and a flurry of activity consumes those on board. Working alongside Knotek is Emily Jones, a scientific program officer, and Lena Weiss, a program manager, both from the Cabot Center. They scramble to prepare the tagging materials as Knotek reels in the line.
But a sand tiger does not emerge from the water. Instead, the crew has caught another type of shark known as a smooth dogfish. It’s a false alarm, but an expected one. Smooth dogfish frequent the same waters and go after the same types of bait. Knotek jokes about how normally they need to get a couple “smooth dogs” out of the way before bagging a sand tiger.
His words prove prophetic, and soon the scientists are reeling in a true sand tiger. With the help of a large net, the shark is soon dumped into a cooler full of ocean water. It flails around the container, flashing rows of needle-like teeth. Just as the researchers begin preparing their instruments, another line shudders. A second sand tiger has been caught.
Now a coordinated dance plays out. Weiss holds the second shark in a net off the side of the boat as Jones and Knotek get to work on the first one. Jones expertly flips the shark, placing her hands at key spots and initiating a trance-like state in the animal known as tonic immobility. She assesses its color and its breathing; she remarks on the beauty of its unique pattern of spots.
Emily Jones, of the Anderson Cabot Center for Ocean Life at the New England Aquarium, holds a juvenile sand tiger shark as her colleagues prepare to insert an acoustic transmitter into its abdomen. – Madison Lucchesi/Boston.com
Local anesthetic is applied to a small portion of the shark’s abdomen before Knotek unsheaths a scalpel. The animal’s skin is so tough that a cut of only a couple inches will dull the blade. Knotek wipes away blood and inserts a small black cylinder into the abdomen.
This acoustic transmitter will send ultrasonic signals from inside the shark for about the next 10 years as the animal matures. A network of receivers in Boston Harbor and along the East Coast will allow scientists to track the animal in a setup Knotek compares to the E-ZPass system used by drivers to quickly pay highway tolls.
Knotek delicately uses a pair of pliers to tie sutures, closing the wound and allowing Jones to let the animal go. After the scientists take a variety of measurements, they release it back into the ocean and repeat the process with the second shark.
The second surgery goes well, aside from a brief moment when the shark’s teeth catch on the net and risk making a small hole much larger.
The two sand tiger catches in quick succession end up being an anomaly. For the rest of the day all that comes up on the lines are a few dogfish and, to Knotek’s disdain, a gnarled spider crab.
Ryan Knotek releases a juvenile sand tiger shark. – Ross Cristantiello/Boston.com
But the lack of continued success does not dampen the mood on board. Reading recommendations are exchanged, pop music is blasted, and snacks are consumed. The researchers share stories of past shark-tagging expeditions and remark on the legendary, solitary Orca recently spotted north of Cape Cod.
As the sun begins to set and the sounds of rush hour traffic grow louder, the vessel returns to the boat ramp where it set off from six hours earlier in Weymouth.
It was a good day, the researchers say. There is an air of exhaustion on board but also a feeling of satisfaction. It is an echo of a small but meaningful moment that occurred hours earlier, when Knotek released the second shark.
As the animal disappeared into the waves, he had let out a contented sigh.
“There’s nothing better looking than that right there. Beautiful.”
Ross CristantielloStaff Writer
Ross Cristantiello, a general assignment news reporter for Boston.com since 2022, covers local politics, crime, the environment, and more.
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