Aquaculture for all

CBF and TNC Support Native Oyster Alternatives

US - The Chesapeake Bay Foundation (CBF) and The Nature Conservancy (TNC) have come out in support of using native oysters to restore the population in Chesapeake Bay, after considering the environmental impacts of alternative approaches highlighted in a study.

Research indicates significant potential with native oysters for industry and environment, while not demonstrating reasonable assurance that the non-native species will be successful or that it will not harm an already compromised estuary Given the available information, the combination of native oyster aquaculture and enhanced native restoration clearly provides the best potential for progress with the least amount of risk.

The Federal government along with Maryland and Virginia have released a long-awaited Environmental Impact Statement evaluating the proposal to introduce a non-native oyster species from Asia into Chesapeake Bay. The study, which also evaluates native species alternatives, does not highlight a preference.

"The combination of native oyster aquaculture and enhanced native restoration clearly provides the best potential for progress with the least amount of risk"
William C. Baker, President of CBF

After following the research conducted to inform the EIS, participating in its scientific review, and reviewing the conclusions of EIS, the CBF and The Nature Conservancy TNC believe that our native oyster holds the best promise - for the citizens, for the oyster industry, and for the Bay itself.

"Given the available information, the combination of native oyster aquaculture and enhanced native restoration clearly provides the best potential for progress with the least amount of risk," said William C. Baker, President of CBF.

"With the right investments and management decisions by the public and private sectors, including our organizations, we can have native oyster populations that provide significant ecological and economic benefits - all without the risk of unintended consequences," added Michael Lipford, Virginia State Director of TNC.

Both organizations see the study as providing a clear path forward. "The scientific community is generally positive about the prospects for native oyster restoration," said William Goldsborough, senior scientist for CBF, citing testimony from a recent congressional hearing. "Recent efforts have shown local successes, including in the Lynnhaven River where combined work has led to a tenfold increase in native oysters, and in the Rappahannock River, where scientists believe they are seeing evidence of the development of disease resistance in large oysters that for years were protected within sanctuaries."

Equally encouraging is the potential for aquaculture of the native oyster. In both states, sterile native oysters, as well as native oysters placed up in the water column, have been found to grow fast, reaching market size well before disease has its impacts. And oyster aquaculture is on the rise - in Virginia, the number of native oysters planted by growers tripled from 2005 to 2007, and the number of market oysters sold by aquaculturists grew from less than 1 million to more than 4.8 million.

"With a wild fishery decades away from large-scale recovery with any species, aquaculture of the native oyster provides a real economic opportunity for watermen who have been struggling with diminished harvests," said Mark Luckenbach, Professor of Marine Science at the Virginia Institute of Marine Science.

While the EIS indicates that the non-native Asian oyster species grows quickly and resists the diseases affecting our native oyster, research also highlights considerable uncertainty for its success, since the Asian oyster faces many of the same challenges that limit our native oyster - and some new ones.

"Regardless of the oyster species, large investments must be made to increase hatchery capacity, restore degraded habitat, and improve water quality," said Mark Bryer, Director of TNC's Chesapeake Bay program. "The EIS indicates that the non-native oyster has greater sensitivity to low dissolved oxygen and greater vulnerability to predation than our native oyster. It is also susceptible to Bonamia, a disease which caused mass mortalities of the non-native oyster in experimental deployments in North Carolina." Recent studies have found that the high salinity waters of the lower Chesapeake Bay are suitable for Bonamia, the same location where the non-native oyster has shown the greatest growth differential from our native oyster.

Studies also indicate other uncertainties with regard to the non-native oyster, including the potential for it to compete with our native oyster and cause local extinctions. Additionally, a recent study by Johns Hopkins University highlighted increased likelihood of the non-native oyster to harbor viruses that are dangerous to humans. The EIS research also concludes that the introduction of sterile non-native oysters will eventually result in reproductive non-native oysters in the Chesapeake, and that the non-native oyster will likely spread along the eastern seaboard with unknown ecological consequences.

"The burden of proof needs to be on the proponents of introduction to show that it will not result in significant problems," added Goldsborough. "Our review of the EIS indicates that burden proof has not been met."

Dr. Denise Breitburg, a senior scientist at the Smithsonian Environmental Research Center summed up the issue by saying, "Given the numerous problems that have been caused by invasive species worldwide, the uncertainty of consequences both within and outside the Bay, the irreversibility of the decision, and the reality that we have not exhausted possibilities for native oyster restoration, I would strongly recommend that it is not time to introduce a non-native oyster species to Chesapeake Bay."

Further Reading

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