Portfolio V: Restoring Oysters To The Chesapeake Bay

The Issue • Our Response • Managing for Success • Achievements • Impacts

The Issue

For nearly a decade, oyster harvests in the Chesapeake Bay have been at all time lows - an average of 200,000 bushels a year in Maryland, down from some 2.5 million bushels during the 1930s and early 80s. Even in those years, harvests were not a reliable index of the health of oysters, which were less than 30 percent of harvests at the

beginning of the century. The long-term decline of oysters has been related to overfishing and the severe cropping of oyster reef habitats, most of which have been further eliminated by runoff and siltation. In the late 50's, parasitic diseases took a foothold and over these years have progressively led to major mortalities of oysters before they reach harvestable size. These diseases, principally two protozoan parasites, Haplosporidium nelsoni (referred to as MSX disease) and Perkinsus marinus (referred to as Dermo), have frustrated oyster repletion efforts.

The economic impact of the fishery's decline on regional economies since the 1980s and the increasing appreciation that oysters play a key ecological role in removing algae, and therefore nutrients, from the water column, led to the Oyster Disease Research Program (ODRP). A congressionally-mandated program, ODRP supports research, outreach and management efforts for restoring oyster populations. While ODRP is coordinated by the National Sea Grant Program, researchers in Maryland and Virginia have been conducting major research studies that have begun to show promising applications for oyster restoration.

In the mid-1990s, it became clear that findings from ODRP and other research efforts, particularly on oyster reefs, had profound implications for oyster management. For example, studies of reefs were clearly demonstrating them to be an important ecological and fisheries habitat, not simply resources for a harvestable product in the Chesapeake Bay. Unlike all other states on the east coast, Maryland's oyster fishery is primarily a public one: since 1960s, harvests have been sustained to some degree by Department of Natural Resources programs, on which millions of bushels of dredged shell are moved during the summer spawning season to areas of traditionally high spat set in order to attract oyster larvae.

The resulting seed is then moved in the fall to public bars for grow-out and eventual harvest. Because the state's primary focus has largely been support of the public fishery in order to maintain annual harvests of two to three million bushels annually, policy for restoring the oyster's ecological function was not, until recently, a principle concern. While there was general public support for maintaining the traditional fishery, it has not been an "active" public; on the other hand, there was little support for oyster restoration for ecological purposes, largely because its case had not been effectively made.

Strong evidence of the importance of the oyster in the Bay's ecology and economy, together with scientific advances on combating oyster disease has provided a foundation for new educational and outreach programs for diverse constituencies, among them, commercial watermen, aquaculturists, seafood processors, scientists, resource managers, policy makers, legislators, citizens and educators.