A group of oyster specialists from universities in Maryland, Virginia and North Carolina have agreed to the first-ever consensus on the key ingredients needed to restore healthy populations of the filter feeder to the Chesapeake Bay.
“For the first time, we have a technical consensus across state lines,” said Donald Boesch, president of the University of Maryland Center for Environmental Science. “This consensus will provide guidance to restore the Chesapeake Bay’s most definitive resource — oysters.”
“The goal was to develop Baywide strategies for oyster restoration based on the best scientific data available,” said Gene Burreson of the Virginia Institute of Marine Science. “I think this group of experts succeeded admirably. Although there are some differences in salinity and disease levels between Virginia and Maryland, we are confident these recommendations will work in both states.”
A small group of experts met in January to reach an agreement on oyster restoration principles. Their recommendations were published in June by the Chesapeake Research Consortium, a nonprofit association of six universities in Virginia, Maryland and Pennsylvania whose research emphasizes Bay issues.
The scientists emphasized that “we must move away from the concept of restoring and managing oysters strictly to support an industry.” Rather, they said, the guiding philosophy should be managing oysters for their ecological value — such as their water-filtering and reef-building capabilities.
Nonetheless, they said, a “sustainable fishery” could take place on a regional basis with regional quotas based on the health of the stock. Ultimately, they said, a fishery should be able to exist without public funds as oysters are recovered.
The most important components of restoration, the scientists agreed, were rebuilding three-dimensional reefs and establishing permanent sanctuaries. The scientists said reefs were important because they provide protection from predators, improve reproduction and survival, and provide vertical habitat structures that are critical for many other species of fish and shellfish.
“It is clear from historical documents that three-dimensional oyster reefs were a dominant feature of the Chesapeake Bay when colonists arrived in the New World,” the scientists said in their consensus report.
Sanctuaries are important to allow for the development and protection of large oysters, which produce many more eggs than small oysters, and may have developed some degree of disease resistance — a trait they may pass on to offspring.
It’s not clear how much sanctuary habitat is needed, but the scientists called for setting aside at least 10 percent of “traditional oyster bar acreage” — or about 50,000 acres. The exact amount of sanctuary area could be modified as more research takes place.
They also called for an end to the practice of moving disease-infected “seed” — young oysters — into areas where the disease is not present, or is present only at low levels. Seed is often moved to improve growth for future harvests — managers say the diseases are widespread so it doesn’t make a difference — but the scientists said such movement, especially into low salinity waters were the diseases are not deadly, can exacerbate problems, especially in times of drought when salinities increase. Key points of agreement among the scientists include:
- The goal of Chesapeake Bay oyster restoration should be to restore and manage oyster populations for their ecological value in such a way that a sustainable fishery can exist while maintaining the essential ecosystem functions of oyster reefs.
- The oyster fishery should be managed regionally based on stock assessments.
- Proper disease management means minimizing, or even prohibiting, the movement of infected oysters.
Essential Components of Oyster Restoration
- Three-dimensional reefs, standing substantially above the bottom, are essential for oyster reproductive success, protection from predators and to create habitat for other organisms.
- Permanent reef sanctuaries permit the long-term growth and protection of large oysters that provide increased fecundity and may lead to the development of disease-resistant oysters.
- For success, both components, three-dimensional reefs and permanent sanctuaries, are necessary; neither component alone will be sufficient.
Reef Siting and Design
- Sanctuary reefs must be placed on hard bottom in areas of natural spatset. A three-dimensional structure equal to at least one half of the water depth is recommended.
- Adult oysters may need to be added to reefs to “jump-start” recruitment.
- Oyster shell is a limited resource in all areas and availability may affect recruitment around reefs.
Long-term goals are to set aside and restore 10 percent of historic productive oyster reef acreage for its habitat and ecological value and to restore a sustainable public fishery that would not require additional public monies.
Short-term goals are to increase spatset, increase the number of adult oysters and to increase habitat and fish utilization of that habitat in tributaries where reef sanctuaries have been established.
Intermediate goals (4-8 years) are to demonstrate the effectiveness of reef sanctuaries in selected tributaries in Maryland and Virginia.
The consensus document is available on the Internet at www.vims.edu - in the news