There have been multiple sightings of great white sharks in New England waters this summer, as there typically are.
But there are other sharks in the area, including in Boston Harbor. And scientists say they deserve some attention, too.
A research team from the New England Aquarium is on a mission to find sand tiger sharks — and to track them over time as their population recovers from a sustained period of overfishing. Sand tigers come up to Massachusetts waters in the summer as juveniles, but because they rarely surface, most people don’t even know they’re here.
Anchored just off the Squantum Marshes in Quincy recently, Ryan Knotek, a research scientist with the aquarium, gripped a fishing rod and reeled in his catch.
“OK, that’s the biggest sand tiger we’ve ever had!” he exclaimed in surprise.
It was still a juvenile, but it was more than 4 feet long, with a mouth full of teeth. Sand tigers can grow to more than 10 feet long, but they’re only interested in fish, so they don’t pose a risk to humans.
Knotek placed the shark into a cooler full of water. It thrashed around at first, but once scientist Mike O’Neill flipped it onto its back and held it, the sand tiger became totally calm. It’s a behavior called tonic immobility.
“Interesting evolutionary thing, but convenient for us,” said Emily Jones, another scientist with the aquarium.
Jones readied a syringe with a local anesthetic. Then Knotek used a scalpel to make an incision in the shark’s abdomen, before squeezing in the tag, which looks a bit like a tube of lipstick. This tag puts out a signal that can be picked up by receivers on buoys up and down the East Coast, allowing the scientists to track the shark’s movement.
When Knotek was done sewing up the incision with surgical precision, he released the shark back into the harbor.
“Adios,” he said, as the shark swam away.
Until relatively recently, the population of sand tiger sharks was decimated by fishing.
“And that fishing pressure between like the ’70s to the ’90s actually depleted their population by like 70 to 90%,” Knotek said.
But then, catching and keeping them was outlawed in the 1990s.
“So for the better part of two decades now, sand tigers have been protected,” Knotek said. “And we are optimistically starting to see some signs of recovery.”
This is a conservation success story in the works. The waters here are far cleaner than they used to be, and an increase in bait fish is now attracting sand tigers to Boston Harbor as a nursery area.
But still, progress is slow. Knotek says about 1-2% of the population is restored each year.
“And the goal is to tag as many of these sharks as we can to just figure out exactly when, where, and why the sharks are in Boston Harbor, with sort of that end goal to maybe get some additional actions towards protections for this species as they try to recover,” he said.
A bit later, Knotek caught another sand tiger, but this one they’d met before. The New England Aquarium team tagged it here last summer.
“So that thing traveled hundreds of miles down to — who knows? Carolinas or Florida — and came back to this exact marsh,” Knotek said with a laugh of amazement.
“[It’s a] demonstration of how massive the ocean is and how small it can be sometimes, when people think about our impact on it,” added O’Neill.
The presence of great white sharks in New England waters is more talked about, Jones said.
“[But] there’s a lot more sharks out there in New England than just the white sharks, and it’s really important that those sharks get attention and funding to gather data,” she said. “Because we just don’t know a lot about them yet.”
The sand tigers will stick around in Boston Harbor until September, before heading back south. And for the next 10 years — until the batteries in the tags they’re carrying run out — scientists will have a window into the behavior of this slowly rebounding species.
