Stan Allen reached into a tank and pulled out a handful of oysters. They had been growing for only about two months and, already, were larger than quarters.
And these oysters, growing in vats at the Virginia Institute of Marine Science, were small compared with their cousins growing in nearby rivers where they could feed on vast crops of algae in nutrient-rich water. “We’re holding them in jails,” quipped Allen, a VIMS researcher.
In fact, the 60,000 oysters being grown in rivers are expected to reach market size of more than 3 inches in September. And, most likely, none of them will have been killed by disease.
For some, the fast-growing, disease-resistant oysters being bred by Allen are a dream come true for the region’s beleaguered oyster industry — and possibly for the Bay. To others, they are a potential nightmare.
That’s because the oysters in Allen’s hand were not the Chesapeake’s native species, Crassostrea virginica. Instead, they were Crassostrea ariakensis, which originates half a world away in China and Japan.
Although the oysters have been rendered sterile, any experiments in which foreign oysters are placed into the Bay system have been strongly opposed by Maryland officials who worry that an accidental introduction is possible and could pose a new challenge to the already battered virginica.
But for watermen who have seen Bay oyster harvests decline to a fraction of their historic levels — and essentially disappear in Virginia — ariakensis offers a ray of hope. Possibly, it could support an aquaculture industry. “This is a dynamite product,” Allen said. But no one will know, he added, without the research that is now under way.
The VIMS research stems from an 1994 directive by the Virginia General Assembly that it explore the potential role of nonnative oysters in rejuvenating the the state’s crippled oyster industry.
In the past two decades, two diseases — MSX and Dermo — have ravaged the Bay’s oysters, killing most of them before they can reach market size. It has not only crippled the oyster industry, but has also been a blow to the health of the Chesapeake as oysters are important water filterers and their reefs are habitat for other species.
While the diseases have affected oysters throughout the Bay, Virginia has suffered most because both MSX and Dermo thrive in its high-salinity water. In recent years, oyster harvests in Virginia have all but ended.
Spurred by the legislature, VIMS scientists first experimented with Crassostrea gigas, also known as the Pacific oyster. That work was not promising. Although gigas proved to be more disease-resistant than virginica, it did not outperform the native oyster in growth except in the highest salinity areas.
Further, it proved to be more susceptible to infestation by mud worms than virginica. And finally, it didn’t look or taste like an oyster from the Chesapeake. Because gigas is widely used in aquaculture elsewhere, oysters grown in the Bay would face stiff worldwide competition for the same product.
At that point, researchers began looking at ariakensis, an oyster they had acquired that was native to Southeast Asia but not grown in aquaculture anywhere. In fact, little was known about the species.
VIMS scientists carefully placed sterile oysters in bags and placed them in different places around the Bay. The result was dramatic. Ariakensis grew faster than virginica in all salinities. In low salinities, it grew about 25 percent larger than virginica, while in high salinities it grew almost twice as big.
“When it gets into a Bay that we think is degraded, it thinks it’s gone to heaven, because it’s better than anywhere it’s been before,” said Jim Wesson, who oversees oyster restoration for the Virginia Marine Resources Commission. “It thrives in this situation where gigas was not thriving.”
Also, ariakensis fared far better with the two diseases that have plagued native oysters. MSX was absent from ariakensis altogether while present in virginica. While some ariakensis oysters had light infections of Dermo, all virginica oysters were infected, often heavily.
All of the virginica oysters died at the medium and high salinity sites, and 81 percent died at the low salinity site. But ariakensis emerged unscathed.
In short, the foreign oyster outperformed the native oyster and was able to reach market size in less than a year.
But that wasn’t all. Last year, 6,000 oysters were grown by aquaculture farmers and tested on the market. Not only did its survival rate and fast growth impress people, but so did its taste.
“It looks like our oyster, and it tastes like our oyster,” Wesson said. “It seems like it could be a unique product for the Chesapeake Bay that would recapture that uniqueness of a Chesapeake oyster, which is different from what all these other countries are doing. So there is potential for marketing a unique Bay product.”
Officials plan more market studies with the 60,000 oysters being grown this year, mostly by watermen. Meanwhile, VIMS scientists, who maintain breeding stocks in quarantined hatcheries, are working to determine whether it would be economically viable to produce enough sterile oysters to support an aquaculture industry.
Wesson sees ariakensis as a potential boost for the recovery of native oysters. By giving watermen the option of raising the foreign species in aquaculture, it can help hold off pressure to reopen harvests on native oysters. That, in turn, allows native oysters that survive diseases a chance to reproduce — rather than being harvested — potentially creating offspring that will also withstand disease.
“Our restoration strategies are sound, but it will take a generation or more to get out of the problem,” Wesson said. “The only way to get there is to leave our oyster alone, and that is what we want to do. It makes ariakensis, as an aquaculture tradeoff, seem to be very attractive. It keeps the industry alive at the same time that we’re building the other oysters back up.”
The Chesapeake Bay Foundation, which had expressed concern about earlier work with gigas — in part because that oyster was being considered for introduction into the Bay rather than just for aquaculture — has not developed a position on ariakensis.
“For right now, we believe it is worthwhile to conduct this kind of work,” said Rob Brumbaugh, a CBF fisheries scientist. “It is certainly responsible for VIMS to be responding to the seafood industry concerns about the continuing sad state of affairs of the oyster industry.”
The organization remains opposed to placing reproductive oysters in the wild, Brumbaugh said. At the same time, he added, the issue is not strictly environmental — ariakensis could play an important role in maintaining the Bay’s struggling fishing communities.
“It’s fairly obviously that the interest is growing within the seafood industry, especially in Virginia, but even in Maryland,” he said. “Certainly, the health of the seafood industry and the prospect for rejuvenating some of the communities around the Bay has to be part of our decision-making on this kind of issue.”
One place where opposition remains firm, though, is across the state line. Maryland officials drove to Virginia to object to any open-water experiments with foreign oysters during public hearings. “Now they are contemplating ramping up the program, and we continue to have concerns,” said Eric Schwaab, director of fisheries with the Maryland Department of Natural Resources.
Schwaab acknowledged that experiments have been well-conducted with little chance of an accidental introduction. The problem, he said, is where the program is headed. “The likely eventuality is that there will be significant interest in the aquaculture industry to use that oyster,” he said.
If production is dramatically increased to rear the millions of oysters that would be needed to support an aquaculture industry, Schwaab said it would become difficult to maintain safeguards that keep reproductive oysters out of the wild. “In the initial stages, they have been dealing with a very carefully controlled trial in which they can track individual oysters,” he said. “At some point, that becomes less likely, or less practical.”
To prevent the accidental introduction of reproducing oysters, VIMS allows only “triploid” oysters in the wild. All others are kept in quarantine systems. Triploids are oysters with three sets of chromosomes, instead of the normal two, which cannot reproduce.
In the original gigas experiments, though, some oysters chemically treated as larvae to become triploids began to revert to normal, diploid oysters. None of those triploids ever reverted to the point where they were capable of reproduction, Allen said. “That’s not to say that wouldn’t happen given a decade or so.”
Nonetheless, Allen has since developed a new method of creating triploids, in which oysters with four sets of chromosomes — or “tetraploids” — are created, then bred with diploids. The technique produces triploids that are more stable and less likely to revert, he said.
As part of the project, Allen is working to develop new testing procedures that could be applied to large-scale production to ensure that all batches of oysters placed in the water are, in fact, triploids. He’s also developing protocols for how oysters should be placed in the water and tracked to make sure all are accounted for. He acknowledged that it’s impossible to be 100 percent certain that no reproductive oysters would make it into the Bay, but with proper safeguards, risks would be minimal.
Schwaab, on the other hand, not only questions whether safeguards can be monitored once commercial-scale production begins, but worries that someone — enthused about the potential of the new oyster — could discreetly begin placing reproductive oysters in the Bay. “You increase the probability that somebody who thinks this is a good idea and doesn’t like all of the controls will take it upon themselves to go a different route,” he said.
History is rife, he noted, of instances where such releases of foreign animals have gone awry, from the gypsy moth now devouring oak forests, to the mute swans eating underwater grass beds to the muskrat-like nutria which are devouring more wetlands in Maryland than development. “You have to look back at recent history,” Schwaab said, “and the introduction of nonnative species is not particularly compelling.”
Although success with ariakensis could give rise to the notion of using it to replace the native oyster, scientists say that would be a monumental task.
“If we really wanted to go full speed and actually restore enough oysters to the Bay to do anything that would approach our old fishery, we are in a much better staring position with our native oyster,” said Mark Luckenbach, a VIMS researcher who has worked with both species.
Populating the Bay with a foreign species would be a massive job, requiring the production of tens of millions of oysters for years. Key questions remain unknown, such as the conditions it needs for spawning. And Luckenbach’s own research suggests that ariakensis may not be able to outcompete virginica in the wild.
And, while ariakensis could help Bay water quality by filtering water — potentially faster than virginica — it may not build reefs, which means it would not provide the habitat value for other species like the native oyster. The bottom line, Luckenbach said, is that ariakensis should not be thought of as a “silver bullet” that would solve the Bay’s oyster problem.
“Ariakensis does seem hardy with respect to the current diseases that are here,” Luckenbach said. “And I would underline ‘current diseases’ that are here. There is no oyster that is resistant to all diseases. And just as oysters move around the world, so do these diseases.”
But, he said, “the potential of this animal for aquaculture, I think, is very, very high.”
That raises its own set of issues, he added. Large, commercial-scale aquaculture sites, like those which raise oysters on the West Coast and in Europe, would likely be considered eyesores in the Bay, and would compete with other water uses in shallow water. If ariakensis is used to launch such an industry here, Luckenbach predicted that a decade from now “the water use conflicts associated with large aquaculture will be the issue, not what species is being grown.”
Luckenbach, who described himself as “firmly on the fence” in the ariakensis issue, cautioned against a rush to judgment on ariakensis based on excitement over initial findings. More thought is needed about the future of aquaculture, and any potential risk of introducing a species not only to Virginia, but to the entire Atlantic coast.
“I’m not saying it shouldn’t be done,” he said. “I’ve got to tell you, it’s an impressive oyster. But it shouldn’t be done lightly.”