More than 400 years ago, Atlantic sturgeon helped to save the starving colonists at Jamestown, who discovered that the giant fish were a reliable food source much of the year. The James River, Capt. John Smith wrote, "had more sturgeon than could be devoured by dog and man."

Archaeologists, in fact, commonly find parts of sturgeon at the earliest settlement's site.

"I call it the foundation fish of America, because without sturgeon, we may be speaking Spanish now, or French," said Albert Spells, Virginia fisheries coordinator for the U.S. Fish and Wildlife Service.

Scientists estimate that fewer than 300 adult sturgeon use the James River for spawning. Nonetheless, it's the healthiest sturgeon population in the Bay. The York River is believed to have an even smaller population. Decades ago, the fish vanished altogether from the Rappahannock, Potomac, Nanticoke and Susquehanna.

The story is the same for most but not all rivers along the East Coast.

Last October, the Natural Resources Defense Council, a national environmental organization, petitioned the National Marine Fisheries Service to list Atlantic sturgeon as an endangered species throughout its range, which in the United States runs from Florida to Maine.

In January, the NMFS announced that the organization's petition contained sufficient information to consider threatened or endangered status under the federal Endangered Species Act.

The NMFS, which is part of the National Oceanic and Atmospheric Administration, must make a final recommendation by next January, and some kind of federal protection under the act is considered likely.

That's because the NMFS' own status review of Atlantic sturgeon, completed in 2007, concluded there was "sufficient evidence" that the Chesapeake Bay population of Atlantic sturgeon was "at risk of becoming endangered in the foreseeable future," and recommended it be listed as threatened under the act. The report suggested that most other East Coast rivers be listed as well.

That's a turnaround from 1998, when federal agencies rejected giving the Atlantic sturgeon threatened or endangered status. At the time, a 40-year harvest moratorium had just been imposed by the Atlantic States Marine Fisheries Commission, which is responsible for managing migratory species along the East Coast. Federal officials expected that moratorium would be sufficient to allow sturgeon populations to rebound.

However, despite the moratorium, some level of illegal harvest is thought to continue, driven by high prices for caviar and declining sturgeon abundance globally. The fish faces other threats as well.

In its petition, the NRDC argued that the moratorium had been inadequate because it failed to address a "gantlet" of other problems such as sturgeon bycatch in other fisheries, impacts of pollution, ship strikes, dredging and global warming.

Sturgeon seem to be highly susceptible to bycatch in other fisheries. The ASMFC estimated in a 2007 report that between 352 and 1,286 sturgeon were killed annually in fisheries targeting other species along the coast. Those figures did not include any mortality from fisheries in rivers and estuaries.

In the James River, scientists have documented an average of about seven adult sturgeon killed annually by boat strikes in recent years, and more may be killed and never seen.

"A population in recovery can't afford to lose a significant number of sexually mature fish year in and year out," said Greg Garman, director of the Virginia Commonwealth University's Center for Environmental Studies

"Up and down the coast, in rivers and estuaries where Atlantic sturgeon were once abundant and their spawning runs were once cultural fixtures, Atlantic sturgeon continue to disappear," the NRDC's petition stated.

Atlantic sturgeon once spawned in as many as 35 coastal rivers from Maine to Florida. (They also spawn in four rivers in Canada.) Many of those rivers once supported tens of thousands of spawning adults. Today, spawning populations exceed 300 in only two, the Hudson in New York and the Altamaha in Georgia. Nine spawning populations have gone extinct, according to the NRDC, including four in the Chesapeake.

Because of the sturgeon's low reproductive rate and sensitivity to poor water quality, scientists estimate that populations with fewer than 300 adults can afford to lose no more than 10 sturgeon a year to human-caused mortality.

Sturgeon are an anadromous fish, meaning they live most of their lives swimming in the ocean, but they return to their native rivers to spawn. The biology of Atlantic sturgeon makes it difficult for their populations to rebound. Females do not reach sexual maturity until they are 10 or more years old.

Females produce only moderate numbers of eggs compared with other species, and do not reach maximum egg production until late in life. Further, they typically return to spawn only once every three to five years.

There are now few of the hard-substrate spawning grounds needed by sturgeon in tidal-fresh reaches of rivers. They have been dredged-sometimes dynamited-to improve shipping channels. Other historical spawning areas have been covered by thick beds of silt.

On top of that, they are more sensitive to poor water quality than many other fish. Their bottom feeding habitats are starved of oxygen and contaminated with toxins. Dams have closed upstream habitats and altered downstream temperatures and water flows.

"Almost everything we've done, we couldn't have done better to negatively affect this animal if we planned it," said Chris Hager, a fisheries scientist in the Sea Grant Marine Advisory Program at the Virginia Institute of Marine Science.

Sturgeon are the largest fish native to the Chesapeake Bay. Archaeologists at Jamestown have found evidence of one sturgeon that was 14 feet long. Sturgeons are known to have weighed more than 800 pounds and live up to 60 years.

They are an ancient species that co-existed with dinosaurs. They look odd because they are covered with armorlike plates rather than scales. But recent centuries have not been kind to the big fish. In the early 1800s, sturgeon were viewed as a nuisance by shad fishermen, who sold them for fertilizer or simply killed them and left them on the shore.

Toward the end of the century, they became a prized catch because of the growing demand for caviar. Their harvest peaked along the East Coast at about 7.4 million pounds in 1890. By 1901, that had dropped to 650,000 pounds, and by the 1920s, the harvest was less than 100,000 pounds.

Globally, all 27 sturgeon species have suffered dramatic population declines, with several going extinct in the last century. Of eight sturgeon species native to North America, most are already listed under the Endangered Species Act.

If they are listed, the NMFS could take action to protect sturgeon from bycatch in other fisheries, and could help protect them from water pollution, dredging and ship strikes, all of which were cited as factors in their continued decline.

"It does justify this listing," said Dave Secor, a fisheries scientist with the University of Maryland Center for Environmental Science who has researched sturgeon in the Bay and along the East Coast. "It could be a good thing on certain issues."

But he and other scientists say the added protection will also make their work on population assessment and restoration more difficult. The act protects species by making it illegal to "take"-harass, harm, pursue, hunt, shoot, wound, kill trap, capture or collect-the species. That also makes it hard for researchers to work with threatened and endangered species.

Researchers also depend on cooperation from watermen, who could be deterred from providing important information if Atlantic sturgeon are listed.

"It does make it more difficult to handle the fish," Garman said. "We're all waiting to see how that plays itself out. But in the past, it has been a double-edged sword for people working on species that become listed."

Brian Richardson, a fisheries biologist with the Maryland Department of Natural Resources, said whether the species is listed as threatened or endangered may be critical to Bay researchers. By law, he said, the secretary of commerce-which oversees the National Marine Fisheries Service-can allow for continued scientific research on a threatened species as long as research protocols are written into the listing language.

"An 'endangered' species designation does not permit any interaction with the species outside of discrete scientific collector permits," Richardson added. In that case, he and others believe that a reward program operated in Maryland that pays watermen to hold captured sturgeon until biologists can tag the fish would likely end. The tagged fish provide information such as what habitats they are using.

"I don't see how that could possibly continue because we are paying watermen that happen to encounter sturgeon a reward," said Steve Minkkinen, who heads the U.S. Fish and Wildlife Services Maryland Fishery Resource Office. "That is a 'take.' There's no way around that."