Oysters are an important part of the Chesapeake Bay. They filter and remove excess nutrients like nitrogen from the water and they grow in reefs that provide habitat for fish and crabs. Oyster reefs support not only the ecosystem, but the economy. As a result of disease, overfishing, degraded water quality, and other problems, only about 1-2 percent of the historic native oyster population remains.

NOAA works with other agencies and organizations to restore oyster reefs in Maryland and Virginia waters of the Chesapeake Bay. NOAA experts lead workgroups that develop and implement restoration work. NOAA scientists conduct sonar surveys and develop habitat analysis to guide projects and monitor progress. And NOAA provides funding to support the hatchery production of baby oysters. Project partners include the Maryland Department of Natural Resources, Virginia Marine Resources Commission, U.S. Army Corps of Engineers, and nonprofit Oyster Recovery Partnership. Universities, local governments, and nonprofits contribute unique skills and resources as well.

The Chesapeake Bay Program, in which NOAA is a partner, has set as a goal to restore oysters to 10 Chesapeake tributaries by 2025. In Maryland, the tributaries are:

Harris Creek

Little Choptank River

Tred Avon River

St. Mary’s River

Manokin River

In Virginia, the tributaries are:

Great Wicomoco River

Lafayette River

Lower York River

Lynnhaven River

Piankatank River

Restoration Blueprint

Partners develop a “blueprint” that describes precisely where restoration will happen in each tributary. Each blueprint includes maps generated by NOAA on where the best places for restoration are in that particular tributary. The blueprints also indicate how many oysters will be needed so that the completed project will meet the definition of “restored.” They also describe—based on location—what is type of restoration is needed. Some areas might only need to be seeded with “spat-on-shell” baby oysters. Others might need to have reefs constructed and to be seeded with spat on shell. Still others might need to have reefs constructed so that naturally occurring spat have a hard place on which to settle and grow.

Experts monitor each restored reef at three and again at six years after restoration to see how big the reefs are and how many oysters live there. In Maryland, for example, 55 out of 56 reefs that were monitored between 2015 and 2017 met the minimum criteria for success, and 75 percent met even higher target criteria. Because the tributaries were chosen in different years, they are all at different stages in their progress toward completion.

All of these large-scale projects are in places that Maryland or Virginia has protected from harvest, giving the oysters the opportunity to grow and thrive. Because oyster larvae float with the currents, larvae produced by a reef in one creek may end up settling in a neighboring creek where harvesting oysters is legal.

Living Laboratory

These restored reef areas serve as a real-life laboratory where scientists can research the benefits they bring to the ecosystem. NOAA scientists and NOAA-funded researchers at academic institutions are exploring the difference in how many—and what species—fish use areas before and after restoration, They are tracking how much nitrogen oyster reefs (and the critters that live on and near them) remove from the water. This can help people decide whether installing oyster reefs is effective so that local and state governments could get “credit” toward helping to clean up the Bay by doing so.

A NOAA-funded study at Morgan State University compared fully mature oyster reefs in the Choptank River System to a fished-down starting point. It showed that the mature reefs would yield a 160 percent increase to blue crab harvest. It would also create an estimated nearly $23 million increase in annual fishing revenues in the two closest counties. The research also indicates that more than 300 (full- and part-time) jobs could result as well.