WILMINGTON — It’s a pleasantly warm May morning, and a small center-console boat containing three men and five fish is gliding along the Brunswick River, a 14-mile-long fork of the Cape Fear River between Navassa and Eagle Island. The hum of nearby traffic on U.S. 17 and the cackle of seagulls are audible above the sputtering of the motor and the splashing sound of four fish thrashing around in a tub full of water. A fifth, not-so-fortunate fish rests on the deck of the boat.
While the men are enjoying their time out on the water, this is not a pleasure cruise, nor is it a commercial fishing operation. The team is part of an effort to tag and study the prehistoric-looking sturgeon, an ancient fish that researchers think has been around since the dinosaurs. Those who work with the species hope to be able to say that for years to come, thus the reason for their tagging operation, funded through a 2011 federal grant split among North Carolina, South Carolina and Georgia.
Joe Facendola of the N.C. Division of Marine Fisheries surgically implants a sonar device inside a sturgeon found along the Brunswick River near Wilmington. Photo: Judy Royal
Both species of sturgeon found in the Cape Fear River, Atlantic and the less common shortnose, are listed as endangered. The shortnose has been protected for decades, while the Atlantic just joined the list in 2012. The moratorium on fishing these has been around since 1998.
“I think we’re just now starting to see the results of the offspring of those fish that successfully were reproducing,” said Joe Facendola, a technician with the N.C. Division of Marine Fisheries.
The four fish in the tub are all juvenile Atlantic sturgeon. Before being returned to the water, all of them will receive an external and internal tag, and the largest will get an extra sonar implant that allows more detailed studying of its movements.
And the fish flopping around on the deck? Well, this flathead catfish won’t be so lucky.
“It’s a non-native species that has been shown to eat sturgeon, so we’ll take him back to look at his gut contents,” Facendola said. “And someone will have him for dinner.”
Once common along the East Coast, Atlantic sturgeon (Acipenser oxyrinchus) became sparse due to a variety of factors, including overfishing for their meat and caviar, dams and locks that block their migration to historic spawning ranges and the eight to 10 years it takes them to become mature enough to reproduce, Facendola said.
“So they have a lot of stuff going against them to be numerous,” he said.
During the tagging trip, Facendola has the most hands-on role. He weighs and measures each sturgeon and clips a small section of their fins with surgical scissors to collect a DNA sample that will allow researchers to age the fish and reveal other important data. He calls out the data to a team member who records it with an electronic tablet, while the other man navigates the boat. Then the tagging begins.
The first is an external anchor tag hanging near the fish’s tail. It’s similar to what you’ll see affixing price tags to items of clothing in a store. Those are designed to alert fishermen on sight that the fish has been tagged for tracking purposes.
Anchor tags obviously won’t last during a sturgeon’s entire lifespan, which can be up to 60 years, so each fish also gets an internal Passive Integrated Transponder (PIT) tag, which is inserted behind its head using a plastic gun with a sharp metal tip. It’s similar to a microchip that’s implanted in a pet dog or cat. Researchers who catch the same sturgeon later may scan it with a reader to see if it’s already been implanted with a PIT tag. None of this day’s catch has previous anchor or PIT tags.
“Basically it beeps out a code and ultrasound, and we have receivers throughout the river from Bald Head…all the way up to Lock and Dam No. 2, and each time one of the fish that we’ve implanted with a receiver swims by the receiver it will pick up the coded beep from that fish so we can tell where it’s gone,” Facendola said. “And the nice thing is the tags we’re using, they’re used fairly commonly so up and down the Atlantic coast all the researchers that are using these tags can pick up the fish from each other’s receivers. I’ll know not only within the Cape Fear where my fish is going, but pretty much up and down the Atlantic coast.”After three of the four fish are tagged and released back into the river, Facendola prepares for his role as sturgeon surgeon on the last one. This fish, which weighs almost 15 pounds, gets an internal sonar implant that will last for three years. Adult sturgeon can reach 15 feet in length and weigh up to 800 pounds.
Before the surgery, Facendola pours an anesthetizing liquid into the tub to relax the fish. A few minutes later, he uses a scalpel to cut an inch-long incision on its belly and pries it open with surgical scissors to insert the cylindrical-shaped transmitter between the fish’s third and fourth scute, or diamond-shaped scale. These scutes can make surgery somewhat difficult.
“I think a good description for cutting into an average one would be like cutting into a football,” Facendola said. “They’re definitely physically resilient.”
The sturgeon barely moves during this process due to a phenomenon called tonic immobility, a state of near-paralysis that occurs when the fish is upside-down and its brain presses on itself. This happens to sharks and alligators, too, Facendola said.
After stitching the fish up and flipping it back over, the sturgeon is ready to return the river and live out its life while helping researchers continue to protect the species.
“We’re trying to figure out some of the areas that are important to the sturgeon for feeding and reproduction in case we need to mitigate any impact that development or land use or anything like that will have,” Facendola said. “We’ll have a better idea of where these important core habitats are. For being kind of commercially exploited and an important fish we still don’t know very much about them in the Cape Fear, although we’re learning more and more.”