The last time fishermen caught an adult Atlantic sturgeon in the Potomac, “The French Connection” was a hit movie , Ike and Tina Turner topped the record charts with “Proud Mary” and an American Motors Gremlin four-door sold for $2,000. Forty-three years later, river watchers are only noting unreliable sturgeon sightings.

Convinced that one of the Potomac’s signature fish might be gone for good , the Interstate Commission on the Potomac River Basin has thrown its support behind a Maryland and U.S. Fish and Wildlife plan to use 60 domesticated Atlantic sturgeon, mostly from New York’s Hudson River, to restock the Potomac.

But the effort to bring them back has its own troubles. Last year, the National Oceanic and Atmospheric Administration’s fishery service listed four varieties of Atlantic sturgeon populations as endangered — the New York Bight, Carolina, South Atlantic and Chesapeake Bay.

The Chesapeake Bay listing has all but dashed the hope of restocking using the Hudson River sturgeon kept at a Maryland hatchery. To preserve the genetic purity of protected animals under the Endangered Species Act, rules prohibit mixing wild and tame species, no matter how much they look alike.

Long story short, Hudson sturgeon aren’t allowed to potentially mess around with their wild cousins in the Potomac. The result is that the Potomac will almost certainly lose its oldest, largest and most distinctive fish.

Marine biologists say it will take more than a century for sturgeon that migrate up and down the Atlantic Coast to return to spawn in Chesapeake Bay tributaries such as the Potomac.

In a desperate bid to move forward with restocking, the commission — with members from Maryland, Virginia, Pennsylvania, West Virginia, the District and the federal government — is preparing to submit a petition and recovery plan to NOAA to persuade it to green light the project.

But even the director of the commission’s living resources division, Jim Cummins, called the effort “pretty iffy.” Still, he said, “We have to try. Otherwise, I’ll never see sturgeon in the Potomac River in my lifetime.”

The loss of sturgeon would diminish any river’s appeal. Sturgeon aren’t the most attractive fish, but their bodies are impressive, growing to 14 feet and weighing as much as 800 pounds.

Like humans, they become reproductive in their teens. They can live to age 60. Like sharks, they roamed the waters when dinosaurs walked the earth. Since the 1800s, they were fished for meat that was pickled, eggs turned into caviar, skin converted to leather and oils used for paints.

Two brothers pulled a 170-pound, 7-foot sturgeon out of the Potomac in April 1970 in Fairfax County, the last known catch. The fish were once so abundant in the Chesapeake that Native Americans grabbed them by hand.

Now the James River is one of a few bay tributaries with enough to merit a count. But the estimated population of 300 is so small, compared to a historic population of 20,000, that removing any for restocking is frowned on by NOAA.

One commissioner, George Reiger, is furious over the potential loss of a fish he loves, and what he called NOAA’s overly rigid protections for the species. “We have fish in those tanks that could jump-start this whole process,” he said.

Besides, said Reiger, a federal appointee, sturgeon “are out there intermingling anyway,” particularly in the ocean before returning to rivers to spawn.

“The boys [at NOAA] with their computersand their policy aren’t as immersed in the real world as they need to be,” he said.

The bad news doesn’t end there for Reiger and his colleagues. Unable to fulfill their mission to re-populate the Potomac, the Hudson sturgeon at the hatchery are probably doomed, swimming on a sort of death row.

GenOn, a utility that supports the program with about $250,000 per year, might pull its funding, leaving no way to provide for the fish, said Brian Richardson, the Maryland hatcheries division manager.

Returning them to the Hudson River isn’t an option, said Marta Nammack, national Endangered Species Act listing coordinator for NOAA Fisheries Service.

“They’ve been domesticated,” she said. “They wouldn’t know how to survive. It would be like euthanasia. Nobody wants to kill a bunch of fish.”

NOAA has similar concerns about releasing the fish in the Potomac. Hatchery fish have a lower survival rate in the wild, and Hudson sturgeon aren’t adapted to the Chesapeake.

The commission, along with Maryland and U.S. Fish and Wildlife, had high hopes for restocking from the hatchery. In 1996, long before the listings, 3,000 sturgeon from other places were released into Maryland’s Nanticoke River.

Watermen were encouraged to recapture those fish to determine if they stuck around and spawned. Plenty of the released sturgeon were caught, but data failed to show what biologists hoped for — a sign that they had babies that would one day return to spawn their own.

The sad truth is that Atlantic sturgeon are complicated, and take a long time to reproduce, making it hard for them to recover from wipeout.

It started with the Atlantic sturgeon’s relative, the smaller short nose sturgeon, protected from fishing in 1967 when the population fell too low. Thirty years later, Maryland closed its Atlantic sturgeon fishery.

NOAA designated them as a species of concern in 2004, leading to last year’s endangered listing.

Endangered listings are a last-ditch attempt to preserve a wild species. Blood lines aren’t the only concern. NOAA is establishing a team of academics and scientists to examine ways to improve water quality, reduce boat strikes, lower bycatches in fishing nets and remove obstacles to their migration.

“We need to make sure the threats to the habitat are no longer there,” Nammack said.

The future for sturgeon in the Potomac is as murky as its waters. Nearly 50 years after the short nose sturgeon was protected, it still hasn’t come back.

“Unfortunately, this species takes a long time to reproduce,” Nammack said. “It does take patience, and it’s tough because it’s not anything that anybody wants to hear.”