When settlers arrived at Jamestown, the first “cash crop” they sent back to England was caviar harvested from Chesapeake Bay sturgeon.

The giant fish — the largest, longest-lived species native to the Bay — have a long and colorful history here: Early settlers reported that natives would test their bravery by lassoing a sturgeon by the tail and trying to hang on until the fish was tired.

During the Revolutionary War, an American soldier was killed while rowing across the Potomac when a giant sturgeon jumped out of the water and landed in his boat.

But the sturgeon were overfished in the late 1800s, and their population never recovered — no sturgeon are known to have spawned in Maryland for decades, and there are only sporadic reports of spawning in Virginia.

Now, some biologists worry, the potential for a sturgeon comeback in the Chesapeake could be hindered by the Bay Program’s proposed new water quality criteria, which they say may not go far enough to clean the water.

The EPA’s Bay Program Office is developing new water quality criteria for dissolved oxygen, water clarity and chlorophyll a (a measure of algae density). By late April, officials expect to set steep new nutrient and sediment reduction goals needed to meet those criteria, which they said will result in a dramatically improved Bay.

Bay Program officials say the criteria were designed with an eye toward making the Chesapeake clean enough for everything from bottom-dwelling worms to underwater grasses to rockfish. But some federal scientists say the criteria may not be not stringent enough for sturgeon, which are particularly sensitive to low dissolved oxygen conditions during warm summer months.

In comments recently submitted to the Bay Program, both the U.S. Fish and Wildlife Service and the National Marine Fisheries Service said the proposed oxygen criteria was insufficient to protect Atlantic sturgeon, which are rare in the Bay, and shortnose sturgeon, which are an endangered species.

The Chesapeake Bay Foundation flatly warned that if the EPA publishes the criteria, it would be a violation of both the Clean Water Act and the Endangered Species Act. Once the EPA finalizes and publishes the criteria, the states are expected to adopt them as enforceable water quality standards.

The EPA’s Bay Program Office was moving to modify the dissolved oxygen criteria before they are set to be finalized at the end of April.

But it is unclear whether the fix being considered will go far enough to placate criticism. “I don’t see their change as anything significant,” said Bill Gerlach, an attorney with the CBF.

At issue is the minimum level of dissolved oxygen that the criteria call for in different parts of the Chesapeake. The Bay Program plans to divide the Chesapeake into different zones or “designated uses,” each of which would have a different numerical criteria for dissolved oxygen.

In open water areas, stretching from the surface to a depth of about 30-40 feet, the Bay Program originally proposed a minimum oxygen concentration of 3 milligrams per liter of water, with a monthly average of 5 mg/l. In deep water areas, below the pycnocline — a natural barrier which prevents the mixing of surface and bottom waters — the criteria call for a monthly average dissolved concentration of 3mg/l during the summer with a minimum of 1.7 mg/l.

But studies suggest that concentrations of 3 mg/l or less are lethal to sturgeon.

The Bay Program is planning to raise criteria levels to 3.2 mg/l in open water areas, based on recently published work showing that sturgeon can survive with that amount of dissolved oxygen in all but the warmest temperatures. Also, if temperatures hit 84 degrees, the revised criteria call for at least 4.3 mg/l of oxygen.

At the same time, officials insist that the 1.7 mg/l concentration is adequate for deep water areas, saying there is no evidence of sturgeon using deep waters in the summer. Because the pycnocline prevents deep water areas from being recharged with oxygen from surface areas, they contend that sturgeon not only avoid those areas today, but also avoided them historically.

Others say that’s not clear.

The USF&WS, which has offered a $100 reward since 1996 to fishermen who report any sturgeon catches in Maryland, said at least two of more than 200 sturgeon captured in summer months came from areas classified as “deep water” by the Bay Program.

Mike Mangold, a USF&WS biologist, said there might be more reports of fish caught in deep areas except that commercial fishermen typically avoid fishing deep waters in the summer — when oxygen conditions are at their worst.

“Our stance was that there is really nobody looking at deep water sites in the summer, so you can’t say they aren’t using it,” he said. “We don’t know.”

It is likely, Mangold said, if there are periods during the summer when dissolved oxygen in deep water areas are adequate “they would probably use it.”

Deep water habitats are important for sturgeon because they are bottom feeders and because they are also stressed by high temperatures found on the surface in the summer. During the warm season, sturgeon face an extreme habitat squeeze: they seek deeper, cooler water to avoid the heat — the areas with the worst dissolved oxygen levels.

By one recent estimate, less than 10 percent of the Bay and its tidal tributaries contain suitable habitat conditions in the summer, as the fish are restricted from surface areas by high temperature, and many deep areas by low dissolved oxygen. Also, suitable areas of habitat are isolated from one another, further restricting the movement of sturgeon.

“No one has a lot of information, said Sheila Eyler, of the USF&WS Maryland Fisheries Resource Office. “But we are trying to err on the side of being protective and cautious on the side of the sturgeon.”

She and others also expressed concern that the Bay Program had made changes in the most recent version of its criteria that shrank the area defined as open water, and increased the amount of deep water areas, in effect reducing the amount of habitat.

If sturgeon are using deep water areas of the Bay, the Clean Water Act requires that any new criteria be sufficient to protect that “existing use” of a waterbody. The CBF contends — though the EPA disputes — that any presence of sturgeon in deep water areas would be considered an existing use.

“I think it’s an extremely serious issue,” said the CBF’s Gerlach. “The way it is now, it could very well be a violation of the Clean Water Act because the existing use is there and it is not being protected, and of the Endangered Species Act because you are placing a federally protected endangered species at risk through a federal action” — the publishing of an EPA-approved criteria

The CBF, in its comments, blasted the Bay Program’s contention that sturgeon are not using deep areas as “conjecture” and warned that in the case of the shortnose sturgeon, it was gambling “with the very existence of a species on this planet.”

In its comments, the National Marine Fisheries Service expressed concern because shortnose sturgeon spend a considerable amount of time in deeper waters, and it stated that it “cannot concur, at this time, with the determination that the revised dissolved oxygen criteria will not adversely affect shortnose sturgeon.” NMFS officials, who are responsible for protecting the shortnose sturgeon, said they were planning to meet with Bay Program representatives to discuss the issue.

Rich Batiuk, associate director for science with the EPA’s Bay Program Office, said that although deep water areas would remain unsuitable for sturgeon, attaining the new dissolved oxygen criteria would open up more areas to them. Sturgeon would be able to dive deeper, have more bottom habitats open for foraging and have more corridors of suitable habitat that allow them to more freely move from river to river than is possible today.

“We’re going to be restoring a tremendous amount of habitat if we actually get these dissolved oxygen levels to where we are talking about,” Batiuk said. “But you can’t avoid the fact that when Mother Nature puts a pycnocline out there, the levels are going to go down. It is a natural barrier even under better conditions than where the Bay is at currently.”

Nonetheless, any potential conflict with the Endangered Species Act involving the shortnose could be problematic. Concerns about the shortnose sturgeon were raised in the Potomac when a group filed suit against the EPA saying discharges from the Washington Aqueduct, which releases water from treatment plants, were harming the endangered shortnose sturgeon and other fish.

The EPA recently proposed a new permit for the aqueduct that would slash sediment discharges, but cost an estimated $60 million. The aqueduct is operated by the Army Corps of Engineers.

Little is known about what conditions Chesapeake sturgeon actually need because the fish were nearly wiped out in the Bay a century ago and never made a comeback. East Coast sturgeon catches, including those in the Chesapeake, peaked in 1890 when 725,000 pounds were landed to meet European demand for caviar and sturgeon meat. But the fish are so slow to reproduce that the sturgeon population could not keep up with fishing pressure. By 1920, East Coast landings had fallen to 22,800 pounds.

Lacking any sign of a coastwide recovery, the Atlantic States Marine Fisheries Commission, a multistate compact responsible for managing migratory fish, in 1998 closed the entire East Coast to Atlantic sturgeon fishing for four decades. Harming shortnose sturgeon, which have been listed as endangered since the 1960s, has been prohibited for decades.

Historically, Atlantic sturgeon are thought to have been more common in the Bay, although old catch records did not distinguish between the two fish.

Both species spawn in freshwater rivers and can live up to 60 years. Atlantic sturgeon are larger, with adults typically reaching lengths of more than 7 feet, and their young — after spending a year or two in the river where they were spawned — spend most of their lives swimming and foraging along the coast.

Shortnose sturgeon are smaller, with adults typically reaching lengths of 3–4 feet. Shortnose usually spend their entire lives in or near the rivers where they were spawned, and typically do not venture into the Atlantic.

The USF&WS is planning a three-year study in the Potomac to look for evidence of spawning by shortnose sturgeon and to learn more about their movements and distribution.

There is no conclusive evidence that either Atlantic or shortnose sturgeon have spawned in Maryland’s portion of the Bay for decades, although Atlantics appear to sporadically reproduce in Virginia, particularly in the James River.

Most of the Atlantic sturgeon caught in the Bay are thought mainly to be juveniles from the Hudson River, which migrate to various feeding grounds along the coast. Genetic analysis indicates the shortnose sturgeon found in the Bay may have migrated from the Delaware Bay, through the Chesapeake and Delaware Canal.

David Secor, a biologist at the University of Maryland’s Center for Environmental Studies who has studied sturgeon in both the Bay and the Hudson River, agrees that improved dissolved oxygen levels in the Chesapeake would benefit sturgeon.

Secor’s work suggests that sturgeon are more sensitive to low dissolved oxygen conditions than other fish, and he credits improvements in dissolved oxygen to rebounds in sturgeon populations in both the Hudson River and Delaware Bay.

But Secor, who helped to develop the Bay Program’s criteria, doubts that dissolved oxygen alone will spur a similar recovery in the Chesapeake.

Being farther south, the Chesapeake is warmer than the Hudson and the Delaware, making the habitat “squeeze” issue more severe. Also, sturgeon need solid substrates in tidal fresh areas for spawning.

That type of habitat is lacking in today’s Bay, whereas the glacial geology of the Delaware and Hudson rivers supplies such habitats in abundance.

“The Chesapeake is an inhospitable place,” Secor said. He noted that the Bay Program’s dissolved oxygen goals would restore water quality to about where it was in the 1950s. But Secor described the 1950s as a “post-sturgeon Bay.” By that point, sturgeon had already been gone for half a century, and they were showing no signs of making a comeback.

Since then, conditions have generally worsened and Secor expressed doubt that deep water areas of the Bay have been used to any great extent by sturgeon since World War II.

In fact, spawning conditions in the Bay are so unfavorable that Secor speculated the Chesapeake may actually be a population “sink” for shortnose sturgeon in the Delaware Bay if they are not able to reproduce in the Chesapeake.

Continued warming of the Bay in the past century has probably also worsened the outlook for sturgeon, Secor said.

“I wish I was more optimistic,” he added. “And, maybe I’m wrong.”

But if he is right, it could bode poorly for any future reintroduction effort in the Chesapeake.

Maryland did a test release of more than 3,000 young Atlantic sturgeon in the Nanticoke River in 1996, and biologists have been waiting for signs of those fish returning to spawn in the Bay — something that can take eight to 10 years. The Maryland Department of Natural Resources has been rearing scores of Atlantic sturgeon with an eye toward initiating a stocking program when those fish become adults.

Eyler, of the USF&WS, cautioned that if the Bay water quality criteria are not stringent enough, it could close the door to any future comeback. “If they are ever to repopulate the Bay, we have to ensure that those habitats are protected — even if sturgeon are not there right now,” she said.

Secor agreed that dissolved oxygen levels needed to be protective for sturgeon using the Bay, even if they spawn someplace else. But he contended the new criteria should accomplish that.

If the Bay is not able to support a significant reproducing sturgeon population, it would be a sign of just how degraded it has become over time. Bay Program officials have long said that they hoped to restore the Bay to what it was like in the 1950s or 1960s, but could never restore conditions like those observed by Capt. John Smith when he explored the Bay in 1608.

“Sturgeon may be a symbol of what we’ve lost in the Chesapeake Bay,” Secor said. “If we could bring back sturgeon, it would signify a huge change in the Chesapeake.”