Once in Dire Straits, Atlantic Sturgeon Are Staging a Comeback on the East Coast

Matt Balazik surveyed Virginia’s James River for the carcass of a local legend. Growing up along the 340-mile tributary to the Chesapeake Bay, the scientist had heard plenty about Atlantic sturgeon, the large, ancient fish that was once abundant in this water. The species had always inspired fascination, here and elsewhere, because of its prehistoric build. Instead of scales, five rows of bony plates run along the length of its torpedo-shaped body—like armor on a dinosaur, a fellow creature of the Cretaceous period. Spotting a sturgeon jump out of the water was thus like glimpsing a living fossil.

But after periods of rampant overfishing and pollution, the fish had nearly vanished from the James and, in its scarcity, gained a certain mythological status. For all his days out on the river, Balazik had never seen one.

So when somebody reported an eight-foot floater near Herring Creek one day in 2007, the then-Virginia Commonwealth University (VCU) graduate student didn’t hesitate to hop in a boat and start scanning the river’s surface for the fish that had long eluded him.

His sweeping search, however, proved fruitless. And as he turned around, he realized his vessel wouldn’t have enough fuel to make it back to VCU’s Rice Rivers Center. Chagrined, he waited by shore for his adviser to ferry over some gas.

Only then did Balazik finally lay eyes on the mammoth fish. One leapt from the water.

“It was a life-changing moment,” says Balazik, now a research ecologist for the United States Army Engineer Research and Development Center.

Over the next two decades, Balazik and colleagues at VCU have started noticing more and more sturgeon jumping in the James. Though the reason for these breaches is still somewhat murky, many scientists believe that coming up for air allows sturgeon to control their buoyancy.

At first, the researchers were “terrible” at catching the fish, Balazik recalls, as they struggled with setting gillnets effectively. Balazik even dived into the water on occasion in hopes of drawing sturgeon out, as he’d initially thought that their splashes were a form of communication.

But over time, Balazik and others at VCU have refined their methods to tag more than 2,500 sturgeon successfully. To catch the fish, they drop a 300-foot net during spawning season and, after leaving it there for 10 or 15 minutes, capture as many as 30 sturgeon before releasing them back into the river. The number they’ve tagged is only a partial representation of the river’s total sturgeon population but is still significantly more than the estimated 300 spawning adults in the James when Balazik spotted his first sturgeon there.

The researchers’ hauls add to a growing body of evidence from Maine to Florida that Atlantic sturgeon are slowly staging a comeback since overfishing brought them to the edge of extinction in the U.S. during the 20th century. A stock assessment released last year concluded that, while Atlantic sturgeon are far less numerous than they were historically, there’s “a 100 percent probability” the population is greater than it was in 1998, when a moratorium on commercially fishing the species went into effect.

“Overall, the coast-wide population appears to be on an increasing trend,” says John Sheppard, a biologist who serves as the Massachusetts representative on the Atlantic States Marine Fisheries Commission, the group behind the report.

Still, the assessment found that recovery of the species can vary greatly between rivers, where Atlantic sturgeon return to spawn after swimming around the ocean. And while the sturgeon tagged by Balazik and others have inspired hope for the endangered fish’s recovery in the James, they’ve also helped illuminate just how vulnerable the species remains.

A recent genetic analysis of these sturgeon estimated that their ancestors were roughly five times more prevalent on the river when Captain John Smith and company settled at Jamestown in 1607. “Wee had more Sturgeon then could be devoured by dogge and man,” Smith later wrote. The early colonists didn’t deplete this plentiful stock much, if at all. But in the late 19th and early 20th centuries, the rise of the commercial caviar industry heightened the demand for Atlantic sturgeon eggs on the James and other waterways, devastating their populations up and down the East Coast. In subsequent decades, the persistence of overfishing, habitat loss and poor water quality threatened to eliminate the species entirely.

Critically, this rapid population decline in the James led to a significant loss of genetic diversity, the analysis found. So today, even as the Atlantic sturgeon gradually recovers—it can take anywhere from 5 to 34 years for Atlantic sturgeon to reach sexual maturity, according to the National Oceanic and Atmospheric Administration—the fish’s diminished stock is less varied and more susceptible to environmental changes than it once was.

“It would take thousands of years for that heterogeneity to come back,” Balazik says.

In the genetic study, which was published this past October in Proceedings of the Royal Society B, researchers at the Smithsonian Institution genetically analyzed fin clips from modern sturgeon and compared them with archaeological samples of the fish from pre-colonial and colonial sites along the river. The DNA of present-day sturgeon diverged depending on whether the fish spawned in fall or spring, which the scientists had anticipated: Balazik and others had already revealed years earlier that two genetically distinct populations of Atlantic sturgeon swim in the James River.

But the archaeological samples defied this seasonal bifurcation. When researchers examined scutes and spines from collections at Jamestown-, Williamsburg- and Woodland-period sites, they couldn’t neatly divide the DNA into fall-spawning and spring-spawning groups. And the degree of genetic diversity raised questions about the fish’s faithfulness to its natal spawning waters. In modern times, sturgeon almost always return to their native rivers to breed, but historical samples suggested that some sturgeon may have abandoned their native rivers to spawn.

“I think that says something about [the historical sturgeon’s] general adaptability and flexibility,” says Natalia Przelomska, a specialist in archaeological genomics who helped extract and analyze the DNA at the Smithsonian’s National Museum of Natural History. “It’s like, OK, this river is not serving us very well at the moment. Maybe there’s more pollution. Maybe it’s at carrying capacity. Let’s migrate to another river.”

Perhaps as a result of moving between rivers to spawn, the genetic makeup of the archaeological sturgeon samples varied more than the DNA of today’s sturgeon in the James. The historical fish still could have been seasonal spawners in the James, says Logan Kistler, a molecular anthropologist and curator of archaeobotany and archaeogenomics at the National Museum of Natural History. But when overfishing nearly wiped out these sturgeon, genetic drift—or when a chance event changes the frequency of certain genes in a population—strengthened. Specifically, in what’s known as a founder effect, a small subset of the surviving population branched off to form its own colony, increasing the segregation of fall-spawning and spring-spawning sturgeon.

“This is just sort of population genetics 101,” Kistler says.

The archaeogenomic analysis was one of the first projects helmed by Kistler at a nascent lab that examines the ancient DNA of plants and animals as well as their relationship to humans. As is often the case in such projects, a limitation of the sturgeon study was the condition of the genetic information at hand; some necessary data was only recoverable from 6 of the 22 archaeological samples.

“Working with ancient DNA, you’re at the mercy of preservation,” Kistler says.

Isaac Wirgin, an environmental toxicologist at the New York University School of Medicine who has studied the fish for three decades, also wonders whether the archaeological samples are definitively from fish that were born in the James. Atlantic sturgeon can migrate great distances before returning to their natal rivers to spawn, according to a paper written by Wirgin and others last year. For example, the researchers discovered Atlantic sturgeon originating from the Hudson River traveling as far south as the Outer Banks in North Carolina and as far north as the Bay of Fundy, between the Canadian provinces of New Brunswick and Nova Scotia.

“These guys move all over the place once they become subadult fish,” Wirgin says. “Maybe they’re 2 to 6 years old. They can leave their natal rivers, and they can go anywhere. They go a long way, and they go to places you wouldn’t expect them to go.”

The researchers in the James River study acknowledge that it’s possible the historical samples could include sturgeon from multiple natal rivers, which could have inflated estimates of genetic diversity. But the scientists are confident that this is unlikely. They used samples from adults, which tend to migrate less than subadults, according to Balazik. And there were enough similar genetic markers to suggest cohesion among the group, per Przelomska and Kistler.

The numbers and migration habits of Atlantic sturgeon can differ greatly by river, Wirgin stresses. The Endangered Species Act defined five distinct population segments of Atlantic sturgeon in the U.S. when the fish was first listed in 2012 to help manage these differences and assess their relative risk. In the Carolina, Chesapeake Bay, New York Bight and South Atlantic regions, they’re considered endangered; in the Gulf of Maine, they’re threatened.

But in that part of the Atlantic, the fish faces a new menace. The Gulf of Maine is one of the fastest-warming ocean areas in the world, which has imperiled the sand lance population that sturgeon and other species feed on, according to Rebecca Quiñones, the conservation science program manager for MassWildlife’s Natural Heritage & Endangered Species Program.

“It takes more calories to survive in a warming environment than it would in a cooler environment,” Quiñones says. “So you’re trying to get more food, and yet, if your food itself is being negatively impacted by those temperatures, there becomes a rub.”

Beyond environmental changes, Balazik mentions unintentional ship strikes as a rising threat to Atlantic sturgeon. But overall, he’s buoyed by just how many of the fish have returned to the James and other rivers now that they’re no longer harvested.

It wasn’t long ago that he assumed he’d never see the fish his grandfather once caught in the James.

“What everyone thought was bleak just a couple decades ago,” he says, “is now a positive recovery story.”