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Great Wicomico site of thriving native oyster reef
All sides weigh in on C. ariakensis introduction to Bay
It's not a matter of which oyster, but if any oyster could thrive in the Bay
Regional leaders say they won't roll out the welcome mat for an Asian oyster that had generated excitement among some seafood growers, saying it poses "unacceptable ecological risks" to the Chesapeake.
After nearly five years of studying the risks and benefits of using the fast-growing Crassostrea ariakensis, state and federal officials say they will instead pursue an "all native" strategy to restore the commercial and ecological value of oysters in the Bay.
As a result, after nearly 8 years of aquaculture studies, the last sterile nonnative oysters will be pulled from the Bay by the end of May. No further research with C. ariakensis oysters-in the wild or in the lab-is planned. And, the idea of repopulating the Bay with a breeding population of the foreign species is off the table.
For watermen and the seafood industry, that means oyster harvests will increasingly come from fast-growing varieties of the native oyster species, which in aquaculture can typically reach market size before succumbing to disease.
The outlook is less clear for restoring the native C. virginica, whose populations are near an all-time low, in the wild.
Those efforts have shown mixed results over the last two decades. Officials cautioned that future restoration projects will likely cost hundreds of millions of dollars over time, and there is no assurance the natives will overcome the diseases that kill that vast majority of oysters before they reach the 3-inch market size.
"We may not be able to guarantee success, but we will give it a hell of a go," said Col. Dionysis Anninos, Norfolk district commander for the U.S. Army Corps of Engineers.
The decision concludes a decade-long debate about whether an alternate species was needed for C. virginica. Once those oysters were so numerous their large reefs were navigational hazards and the Native Americans called the Chesapeake the "great shellfish Bay."
But overfishing, habitat loss and the arrival in recent decades of two devastating diseases, MSX and Dermo, have left the population at an all-time low. The loss was a blow not only to harvesters, but to the ecosystem, which relied on oysters to filter the water, and whose massive reefs provided habitat for a host of other species.
In the meantime, interest in C. ariakensis-which was brought to the region in the early 1990s by scientists who were primarily researching other nonnative species-soared when tests showed they grew fast, were popular with consumers and were resistant to diseases that plague C. virginica.
That interest led Maryland and Virginia in 2004 to propose the introduction of a breeding population of C. ariakensis. The request triggered the need for an Environmental Impact Statement, which was produced by the two states and the Corps, which must approve projects using nonnative oysters in the Bay.
They released a draft 1,500-page review in October that examined a range of options, from an outright introduction of reproductive nonnative oysters, to allowing the use of sterile nonnatives in aquaculture, to using only native oysters. But that draft offered no recommended alternative.
The draft environmental impact statement did not reveal any concrete evidence that C. ariakensis would harm the Bay. But it said a host of uncertainties made it impossible to predict how it would act in the Bay, and raised some concerns that it could harm the native species.
Studies cited in the document suggest C. ariakensis had some drawbacks. Its thinner shell makes it more susceptible to predation, and it appears to suffer much greater mortality than the native species when exposed to low-oxygen conditions, a common summer occurrence for many deeper oyster habitats in the Bay. It also suffered greater mortalities when exposed to some common harmful algae species found in the Chesapeake.
The prospect of using a nonnative oysters drew widespread opposition from states outside the Bay, scientists, environmental groups and federal agencies, which warned that any introduction would have unpredictable consequences and would be irreversible. Most also opposed commercial-scale aquaculture using sterile C. ariakensis, contending that it would inevitably lead to an accidental introduction over time. The majority of the more than 2,300 public comments opposed the use of the nonative oyster.
After further review, officials agreed in April that uncertainties about the possible impact of C. ariakensis remained too great to permit its use. The decision will be issued in the final Environmental Impact Statement, expected to be released in June.
The decision was praised by environmental groups. Roy Hoagland, vice president for environmental protection and restoration with the Chesapeake Bay Foundation, said it "correctly recognized the dangers that nonnative oysters pose as well as the enormous potential for restoration of the native population."
But it was a blow to some watermen and representatives of the seafood industry who saw the fast-growing oyster as a potential building block to restoring their industry.
Frances Porter, president of the Virginia Seafood Council, called the decision a "disservice to the Bay."
"They never could quantify risks," she said. "We're dealing more with fear than fact." The council has supported a series of in-the-water trials since 1991 in which growers raised sterile C. ariakensis in contained trays. About 7 million oysters were raised and marketed during that time, yet there was "no evidence of any escape," Porter said.
"The Virginia Seafood Council did all the right things," she said. "We followed every guideline in their permits. We crossed every T and dotted every I."
She said seafood growers had no objection to using native oysters in aquaculture, but wanted to have the option of rearing C. ariakensis as a complementary product, and have it available if a bad disease year affected the natives.
In all, nearly $17 million went into the development of the EIS, most of which was for research on C. ariakensis, a native of China which previously had been little studied.
Ironically, it was work aimed at C. ariakensis that showed that the native oyster could be profitably grown in aquaculture. To minimize any chance of introduction, early aquaculture tests using C. ariakensis were conducted with oysters bred to be sterile. But, scientists said, part of the reason for their rapid growth was that sterile oysters put no energy into reproduction.
When similar tests were conducted with sterile C. virginica, they also grew faster, though not as rapidly as C. ariakensis. Nonetheless, the work showed that most sterile C. virginica could reach market size in aquaculture without succumbing to disease.
"That is a clear alternative that we didn't know about when we started this work," said Peyton Robertson, director of the National Oceanic and Atmospheric Administration's Chesapeake Bay Office, which funded much of the C. ariakensis research. "That addresses a market need to have a viable alternative."
The amount of aquaculture using native oysters in Virginia has grown sharply in recent years, and Maryland is starting to promote aquaculture as well.
The more problematic task, officials agree, will be restoring native oysters in the wild and the ecological services they once provided. Besides being devastated by two diseases, more than 80 percent of the oyster habitat in the Bay has been lost or degraded. Oysters require solid substrates for their young-or spat-to land on. Loss of that solid substrate means costly restoration efforts are needed, often with increasingly scarce oyster shells, before areas can be "seeded" with hatchery-reared larvae.
The hope is that oysters that survive diseases will reproduce and eventually lead to a more disease-resistant population, although that could take decades.
While some restoration projects have been successes-such as the Lynnhaven and Great Wicomico rivers in Virginia, and some low-salinity areas of Maryland rivers-most which have taken place over the last two decades have failed.
"I think we can expect pockets of successes on various tributaries of the Bay with the natives. I'm confident we can do that," Anninos said. "I'm not that confident that we can bring back the oyster Baywide from what I see today."
Virginia Secretary of Natural Resources Preston Bryant agreed that successes would be limited to small tributaries with favorable conditions. "But," he added, "achieving pockets of success is not something that I would call a broad ecological success nor a broad economic success. I remain to be convinced that we can have extraordinary success Baywide. I pray that I'm wrong."
The report said restoring native oysters could cost $50 million annually over a decade. State and federal agencies this year will spend more than ever on projects aimed at restoring the native oyster but nowhere near $50 million. The National Oceanic and Atmospheric Administration is providing $4.6 million, the Army Corps of Engineers $2 million, the state of Maryland $5 million, and the state of Virginia between $500,000 and $1 million.
Maryland Secretary of Natural Resources John Griffin said native oyster restoration will take patience, as well as an ability to learn from areas where there are successes and to apply these lessons to other areas.
"We've got to do this piece by piece," Griffin said. "We've got to get in the trenches and slug it out. We have to show success, and success will create more success and generate more funding. This is not an overnight proposition."
Because efforts with native oysters may not be successful, the agreement left the door open for further research with C. ariakensis-albeit slightly. That work could take place only if all states and federal agencies involved in the review process sign off.
But Anninos said further research could clarify the level of risk posed by C. ariakensis if it were released in the Bay, and the likelihood that aquaculture using sterile oysters-a process not 100 percent effective-would actually lead to an accidental introduction.
"We may or may not be successful in our efforts with our native oysters," Anninos said. "So it is prudent that we allow for continued experiments in a scientific research environment to possibly gain additional knowledge on the nonnative animals."
