Oysters play many important roles in the Chesapeake Bay. They are a valuable fishery that supports both significant cultural heritage and emerging aquaculture interests. But they also provide critical benefits to the Bay ecosystem—they filter and remove excess nutrients like nitrogen from the water and they grow in reefs that provide habitat for fish and crabs. People are now realizing the many ways in which oyster reefs support not only the ecosystem, but the economy.
Due to overfishing and other problems like disease, only about 1% of the historic oyster population remains. To return more oysters to the Bay, organizations ranging from local community associations to federal agencies have implemented restoration projects for several decades. While these projects accomplished important work, most were rather small in size.
To achieve significant and lasting progress, the Chesapeake Bay Program, in which NOAA is a partner, realized that large-scale restoration was needed, and committed to restore oysters to 10 Chesapeake tributaries by 2025 in the Chesapeake Bay Watershed Agreement. Work is under way in both Maryland and Virginia waters.
NOAA plays key roles in this effort. NOAA experts lead workgroups in Maryland and Virginia that develop and implement restoration work. NOAA scientists carry out needed work, using sonar surveys and conducting habitat analysis. Partnerships among NOAA, the Maryland Department of Natural Resources, Virginia Marine Resources Commission, U.S. Army Corps of Engineers, and nonprofit Oyster Recovery Partnership are key to making this large-scale restoration possible, and universities, local governments, and nonprofits contribute unique skills and resources as well.
For each tributary selected, the relevant Workgroup develops a “blueprint” that describes precisely where restoration will happen. Each blueprint includes maps generated by the NOAA Chesapeake Bay Office on where the best places for restoration are—for example, restoration is not a good idea on soft areas where constructed reefs would easily sink into the mud, but can be highly successful where historic reefs once thrived. The blueprints also indicate how many oysters—both in sheer numbers of oysters and in extent of healthy oyster reef habitat—will be needed so that the completed project will meet the definition of “restored” that has been agreed to by Chesapeake Bay scientists.
NOAA and partners then implement restoration according to the blueprint. Some places would be ideal for oysters, but have neither existing reef structure nor oysters. In these places, reefs need to be constructed—using oyster or other shells and stone—and then seeded with baby oysters, which are grown in a specialized hatchery. Other places have existing reef structure, but need a “kick start” with a seeding of baby oysters. Still others need structure—and thus need reefs to be constructed—but are in areas where they will likely receive baby oysters floating in on the currents naturally.
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. NOAA and partners track data and report findings. Restoration efforts have been largely successful. In Maryland, for example, 55 out of 56 reefs that were monitored between 2015 and 2017 met the minimum criteria for success, and 75% met even higher target criteria.
These restoration projects involve significant financial investment and other resources, but they can result in big achievements: The Harris Creek restoration project restored more than 350 acres of healthy oyster reef habitat. That’s bigger than the National Mall in Washington, D.C., from the foot of Capitol Hill all the way to the Lincoln Memorial!
Restored reefs provide benefits for recreational anglers, who flock to reef areas as many fish use the structure of oyster reefs as a place to hide from predators or to find food. An iconic species of the Bay, striped bass, is also known as rockfish because they enjoy hanging out near oyster reef “rock.” To highlight this vibrant habitat, the Chesapeake Bay Foundation now holds a fishing tournament where all the action is on or near restored reefs.
These restored reef areas also give scientists a unique opportunity—a real-life laboratory where they can research the benefits restored reefs bring. 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, and are tracking how much nitrogen oyster reefs and the critters that live on and near them remove from the water. Knowing more about denitrification rates can help people decide whether installing oyster reefs is so effective that local and state governments could get “credit” toward helping to clean up the Bay by doing so.
And NOAA-funded research is also putting some numbers to just how valuable oyster reefs are: A study at Morgan State University indicates that—compared with a fished-down starting point—fully mature oyster reefs in the Choptank River System (on Maryland’s Eastern Shore) would yield a 160% increase to blue crab harvest and an estimated nearly $23 million increase in annual fishing revenues in the two closest counties. The research also indicates that more than 300 jobs (combination of full and part time) could result as well.
All of these large-scale projects are in places that the states have protected from harvest, giving them 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.
Having more oysters in the Bay is good for everyone—for people who fish and swim in its waters, for people who count on a healthy Bay for their livelihood, and for the fish, crab, and other critters who live there!
