State and federal officials are reviewing more than 2,000 comments generated from states, scientists, industry groups, politicians and others who weighed in on whether nonnative oysters should have a place in the Chesapeake's future.

As expected, the comments reflect strong support for use of Crassostrea ariakensis in the Bay from watermen, the seafood industry and a number of lawmakers.

But any use of the nonnative oysters in the Chesapeake drew nearly unified opposition from other coastal states, federal agencies, scientists and environmental groups who warned C. ariakensis poses substantial risks and that any introduction would likely be irreversible

At the January meeting of the Chesapeake Bay Commission meeting, Col. Dionysios Anninos, district engineer for the Norfolk District of the Army Corps of Engineers, said the Corps had received about 2,300 letters during the comment period last fall.

The Corps, along with the states of Maryland and Virginia, oversaw the five-year development of a nearly 1,500-page Programmatic Environmental Impact Statement examining oyster management options in the Chesapeake, including the potential use of C. ariakensis, an oyster native to China.

Of the comments received, 1,775 were form letters opposing the use of nonnative oysters in the Bay. Of the remaining comments, most supported using only native oysters in the Bay, Anninos said. A smaller number supported the use of sterile nonnative oysters in aquaculture. An outright introduction of a breeding C. ariakensis population received the least support.

Anninos added that the final decision "will not be decided by popular vote" but would reflect "sound science."

Despite the large number of comments, Anninos said, they contained "no new data that will delay the EIS or cause us to go back and review anything."

As a result, a final document, with a preferred alternative, is expected to be released in the April-May time frame, followed by 30 days of public comment. A final decision would be made in the May-June time frame.

Because the EIS is undertaken jointly by the Corps and the two states, it is possible that each could reach a different conclusion, although Anninos said he hoped the partners could reach a joint decision.

Because it is a Programmatic Environmental Impact Statement, it is a program-level analysis, not a review of any specific project. It could, for example, approve of the concept of large-scale aquaculture with nonnative oysters, but any specific proposal would still have to go through the formal permit process.

Anninos stressed the review is "not a permit-ready document."

The PEIS explored options to restore the ecological role of oysters in the Bay and the economic benefits of a commercial fishery. The ultimate goal was to establish an oyster population that would reach a level of abundance in the Bay adequate to support sustainable harvests comparable to those seen in from 1920-1970. That would translate into about 12 billion market-size oysters, which could support an annual harvest of 1.4 billion oysters, or 5 million bushels, the PEIS said. In contrast, only about 809 million market-size oysters existed in the Bay in 2004.

Although the review examined eight alternatives, from no action to an outright introduction of breeding C. ariakensis oysters into the Bay, no single option would meet both the economic and ecological goals for oyster restoration. Therefore, the PEIS focused on three alternatives that combined multiple options. One used native oysters in restoration and in aquaculture; one allowed the use of sterile C. ariakensis oysters in aquaculture; and the third allowed sterile C. ariakensis in aquaculture but would also allow the introduction of a breeding population into the Bay.

All of the options rely on aquaculture to meet the commercial goal, effectively separating economic and ecological goals.

Regardless of which option is ultimately recommended, Anninos said, "we will not abandon the native oyster."

The Corps has not publicly released the written comments it has received. But comments obtained independently by the Bay Journal show that the use of nonnative oysters, especially the use of sterile oysters-which grow faster-in aquaculture, was strongly supported by members of the seafood industry, which has been hard-hit by the loss of oysters in the Bay. Unlike the native species, C. ariakensis has shown an ability to resist diseases that contributed to the demise of the native C. virginica, and it also grows faster than the native species.

Opponents typically objected to any use of nonnative oysters. The contend that the use of sterile C. ariakensis oysters in aquaculture would eventually lead to a breeding population in the Bay because the technique used to make oysters sterile is not 100 percent effective. They expressed numerous concerns about C. ariakensis in the wild, saying it could interfere with reproduction of native oysters, and even pose a threat to human health.

Much of the opposition came from other East Coast states who contended that the PEIS did not examine potential impacts outside the Chesapeake.

The Atlantic States Marine Fisheries Commission, which represents all East Coast states, said if introduced, the nonnative oyster "would spread to other coastal waters outside of the Chesapeake Bay. The uncertainties and risks associated with this spread are too great to support the introduction of a nonnative species."

New York's Department of Environmental Conservation contended that the species has the potential to spread from Connecticut to the Yucatan Peninsula in Mexico. Before a decision is made, it said, a study "that considers the magnitude of the potential impacts on Atlantic coastal states must be undertaken."

"Because this issue has not been fully evaluated in the PEIS, it does not provide adequate justification and scientific basis to support the introduction of a nonnative species," the letter said.

An often-cited concern was the potential seen in some studies for C. ariakensis to interfere with fertilization by the native oyster, thereby hurting the reproductive ability of native oysters in places with heathy populations.

North Carolina officials, for example, said if C. ariakensis spread to their waters, it could reduce the rate of successful fertilization by up to 50 percent. "If the objective is to continue to restore the native oyster, then we cannot add another factor that will negatively impact the ability of Crassostrea virginica to overcome habitat loss, impaired water quality, disease and overharvesting," said the letter from the state Marine Fisheries Commission.

North Carolina has also conducted experiments with C. ariakensis but delayed any decision on its use until the PEIS was released. In its comments, the Marine Fisheries Commission said studies suggesting C. ariakensis has a poor tolerance of low-dissolved oxygen levels and is highly susceptible to predation and vulnerable to other diseases such as Bonamia, made it a poor candidate for an introduction.

North Carolina's letter said its native oyster population rebounded as oysters have become more resistant to disease, harvests were reduced and oyster restoration efforts were increased. It said similar efforts could help to revive the native species in the Chesapeake.

Some scientists raised human health concerns about C. ariakensis. While it grows fast, it also accumulates potentially harmful substances at a faster rate than the native species.

Robert Lawrence, a professor of Environmental Health Sciences, Health Policy and International Health at the Johns Hopkins Bloomberg School of Public Health, said their studies showed that C. ariakensis was significantly more likely to harbor human viruses than native oysters.

In their work, 56 percent of all C. ariakensis tested were positive for human norovirus, compared with only 16 percent of C. virginica. The nonnative species also accumulated pathogens over a wider range of salinities, and retained them for a longer period of time.

Several states cited those concerns as a threat to coastal shellfish industries if consumers began avoiding shellfish. South Carolina, Delaware, New Jersey and the Gulf States Marine Fisheries Commission all submitted comments opposing any use of nonnative oysters.

The Bay's scientific community also appeared to largely line up against the use of nonnative oysters.

The Bay Program's Scientific and Technical Advisory Committee said the use of native oysters had "the highest likelihood of providing both ecological and economic benefits within Chesapeake Bay, while simultaneously providing the lowest risk of irreversible ecological harm"

The report said native oysters in nearby states, as well as in the Bay, are beginning to show "encouraging" signs of disease resistance and that management actions could be adjusted to promote those traits, such as allowing larger, disease-tolerant oysters to reproduce rather than be harvested. And, the use of sterile C. virginica oysters is showing promise for aquaculture.

STAC said the PEIS overstated the benefits of C. ariakensis in a number of places while understating its risks. For example, the PEIS concludes that C. ariakensis is resistant to Dermo-one of the diseases lethal to native oysters-but does not include the caveat that they can succumb to the disease when also exposed to other stressors.

It also says the poor tolerance of C. ariakensis to low-dissolved oxygen may make more habitat off-limits than is indicated in the report.

STAC also took issue with a statement in the PEIS that the risk to native oysters through reproductive interference is problematic only if the C. ariakensis population "were to become much larger than the Eastern oyster population." That, STAC noted, would be the goal of a C. ariakensis introduction, and as its population grows, the nonnative could have an increasingly negative impact on C. virginica.

The Virginia Institute of Marine Science also opposed the introduction of breeding nonnative oysters, saying its vulnerability to low-dissolved oxygen, predation and other factors meant they would "have difficulty in establishing a naturalized population of significant magnitude." Should they become established, they cited the same concern as STAC-that the potential for cross-fertilization, which does not produce viable larvae, could make recovery of the native species more difficult as the nonnative population grows.

Therefore, it said achieving a large population of C. ariakensis would likely prohibit the stated goal of also restoring the native oyster.

VIMS scientists also expressed doubt about the commercial viability of using nonnative oysters in aquaculture, saying the costs of scaling up production, which would require new hatcheries and increased biosecurity to prevent accidental releases, would likely make such a venture unprofitable.

Rather, it supported the option that relied on native species for both restoration and aquaculture.

Federal agencies that submitted comments-the U.S. Fish and Wildlife Service, the National Oceanic and Atmospheric Administration and the EPA, were united in their opposition to any use of C. ariakensis.

While opponents of the use of nonnative oyster highlighted risks, supporters touted the potential benefits to the struggling seafood industry.

A.J. Erskine, a biologist who oversaw fields tests with C. ariakensis for the Virginia Seafood Council and now is aquaculture manager and field scientist for Bevans Oyster Company and Cowart Seafood Corp. on Virginia's Northern Neck, supported using both native and nonnative oysters in aquaculture.

While C. virginica offers a superior product for the half-shell market, Erskine said the nonnative species provides the best source for shucked oysters, which accounts for 80-90 percent of the market.

Erskine said C. ariakensis was two to three times more profitable to growers than sterile C. virginica because it produces more meat per bushel of oysters, grows faster and has less mortality than the native oyster. With proper biosecurity measures, the use of sterile C. ariakensis is a "biologically safe alternative that poses little to no reproductive risk."

Virginia Del. Albert Pollard said sterile C. ariakensis aquaculture offered "the only chance to reach the goal of a 5-million bushel harvest out of Chesapeake Bay waterways."

Pollard said at the same age, 182 sterile C. ariakensis produce 1 gallon of meat, while it takes 400 native oysters to produce the same amount. Overall, he said, the nonnative "is bigger, grows faster, is more disease-resistant, and requires less labor to harvest and shuck per pound sold."

He said a number of low-cost security efforts could greatly reduce the risk of an accidental introduction. "Great strides have been made in producing a sterile native oyster suitable for aquaculture but this animal preference still lags behind C. ariakensis," Pollard said.

"Nothing in life is risk-free," he added. "Therefore, it seems in my mind that the preferred alternative should focus on minimizing risk to an acceptable level with the goal of sterile nonnative oyster in aquaculture."

The Virginia Seafood Council, which has long advocated using C. ariakensis oysters, said it "strongly supports" the introduction of breeding nonnative oysters into the Bay while continuing to use sterile C. ariakensis in aquaculture and continuing restoration efforts with the native species.

In its letter, the council said concerns about risks from the nonnative oyster "remain little more than conjecture." It said "the ability of the nonnative oyster to filter the Bay has been proven" and there was "no information that the nonnative would be detrimental to the health of the Bay."

If policy-makers could not support an outright introduction, the council said it would support a ramped-up aquaculture effort using sterile C. ariakensis oysters. "With permission to grow [sterile] nonnatives we would be able to place millions of contained specimens in the Bay to begin the massive filtering job that needs to be done and grow the oysters to market size to support the commercial oyster industry. This option has value to the Bay and the commercial industry and could allay some fears associated" with a reproducing population in the water.

Aquaculture with either species is relatively inexpensive compared to building wild populations because most of the Bay's potential habitat is severely degraded and must be rebuilt. The study projected that over 10 years, nonnative introduction scenarios could cost $500 million, while the native restoration could cost $700 million, with no guaranteed outcome for either.

C. Ariakensis PEIS Highlights

Research supporting the draft Environmental Impact Statement found both positive aspects of Crassostrea ariakensis, as well as a number of potential problems or uncertainties. Some of the highlights cited in the PEIS:

Positive factors

  • Studies indicate it is generally resistant to MSX and Dermo.
  • Sterile oysters in aquaculture and reproductive-capable oysters in the laboratory both grew at significantly faster rates than native oysters, with the greatest advantage occurring in high-salinity water.
  • It has a longer growing season than native oysters.
  • Laboratory studies suggest the mortality of its larvae after settlement appears to be lower than those of native oysters.
  • Preliminary evidence suggests that it is capable of growing and reproducing over the same range of salinities as the native oyster.

Negative factors or unknowns

  • Loss of suitable oyster habitat would be a constraint on any oyster introduction effort.
  • Because of the small breeding population used to rear C. ariakensis oysters for use in the Bay, they may lack sufficient genetic diversity to withstand environmental fluctuations in the Chesapeake.
  • Studies suggest C. ariakensis is much more vulnerable to low-oxygen conditions than the native oyster, which may restrict its ability to colonize suitable habitat in deeper water, where low-oxygen conditions are common.
  • Spawning interactions between C. ariakensis and the native oyster could affect the growth and dispersal of native and nonnative oysters in areas where both populations overlap.
  • C. ariakensis appears to be more adversely affected by some harmful algae bloom species found in the Bay than the native oyster.
  • Juvenile C. ariakensis oysters appear to be somewhat more susceptible to predators than juvenile native oysters.
  • C. ariakensis oysters in high- salinity water suffer high mortality rates when exposed to Bonamia, a nonnative parasite recently discovered in North Carolina that could find its way into the Chesapeake in the future.

Combined Alternatives for Oysters

The Environmental Impact Statement initially explored eight options, but concluded that no single action could meet both the economic and ecological goals for oyster restoration.

Instead, it presented three combinations of those alternatives.

They included:

8A: Only Use Native Oysters

This would:

  • Enhance efforts to restore native oysters.
  • Impose a temporary harvest moratorium and a compensation program for the oyster industries.
  • Use native oysters in aquaculture.

8B: Use Native Oysters & C. Ariakensis Oysters

This would:

  • Enhance efforts to restore native oysters.
  • Impose a temporary harvest moratorium and a compensation program for the oyster industries.
  • Use native oysters in aquaculture.
  • Use sterile C. ariakensis oysters in aquaculture.

8C: Use Native Oysters & C. Ariakensis Oysters

This would:

  • Enhance efforts to restore native oysters.
  • Impose a temporary harvest moratorium and a compensation program for the oyster industries
  • Use native oysters in aquaculture.
  • Use sterile C. ariakensis oysters in aquaculture.
  • Introduce reproductive C. ariakensis oysters into the Bay.