A clump of oysters collected from Harris Creek Oyster Sanctuary on Maryland's Eastern Shore. (Photo by Will Parson/Chesapeake Bay Program)

Oyster reefs are an invaluable part of the Chesapeake Bay ecosystem. They improve water quality, provide food and habitat to other animals and help protect shorelines. According to recent research, they may even boost blue crab populations. However, less than 1% of the historic oyster population remains in the Chesapeake Bay due to disease, overharvesting, poor water quality and habitat loss.

Chesapeake Bay Program partners are working to restore oyster habitat and populations to 10 tributaries by 2025 as part of the Chesapeake Bay Watershed Agreement. In order for the outcome to be considered complete, the partnership must develop a tributary restoration plan for each site, construct and seed reefs, and then monitor and evaluate the reefs for progress. Monitoring and evaluation—which will take place at three- and six-year intervals following construction and seeding—will determine whether a reef can be considered restored and contribute toward meeting the outcome. This phase will not be complete until after 2025. To date, two of the ten tributaries—Harris Creek in Maryland and the Lafayette River in Virginia—are considered complete while the eight others vary in stages.

Maryland Oyster Restoration Update

According to Maryland’s Oyster Restoration Update, Chesapeake Bay Program partners have constructed 788 acres of oyster reefs toward restoring five tributaries in Maryland. These reefs were constructed by building a substrate—a foundation consisting of hard material—followed by planting hatchery-produced oyster seed or by placing only seed onto existing remnant reefs. The University of Maryland’s Horn Point Oyster Hatchery is the primary seed producer for the effort. In 2019, record rainfall, with resulting freshwater flows and below-average salinities, resulted in low oyster seed production at the hatchery. This meant there was only enough seed to plant on 11 acres when a typical year is around 100 acres.

  • Harris Creek: Harris Creek is the largest oyster restoration sanctuary in the United States and has become an internationally recognized example of large-scale restoration with 351 acres completed. Initial oyster restoration work was finished in 2015, making it the first Bay tributary to be considered complete under the Oyster Outcome in the Watershed Agreement. Since completion, efforts have focused on monitoring, and conducting additional seedings.
  • Little Choptank River: In 2019, eight additional acres of reefs were restored, bringing the total acreage in the Little Choptank to 351. The restoration plan calls for 440 acres of reefs to be re-established, however the river can be considered minimally restored as long as at least 50% (343 acres) are completed. Seven remaining acres in the river are suitable for seed-only reef construction, and these are a high priority for completing in the summer of 2020.
  • Tred Avon River: As of 2019, nearly 87 acres of reefs have been restored toward the 147-acre goal. The U.S. Army Corps of Engineers plans to construct approximately 40 more acres of reefs as early as December 2020. An additional six acres are suitable for restoring by planting seed-only reefs and are high priority for seeding in 2020.
  • Upper St. Mary’s River: Pre-restoration sonar and oyster population surveys have been completed. The Maryland and Virginia Oyster Restoration Interagency Team has completed a draft plan that calls for 60 acres of reefs to be restored in the river. Partners plan to construct nine acres of substrate reefs and an additional 16 acres of seed-only reefs. These 16 acres are a high priority for planting in 2020.
  • Manokin River: In June 2019, the Manokin River was approved as the tenth tributary under the Oyster Outcome. The workgroup has developed a draft restoration plan that is currently under review. The draft plan calls for a total of 441 acres of reefs in the river, but this goal is subject to change based on final pre-restoration sonar and oyster population surveys in the river.

Virginia Oyster Restoration Update

According to Virginia’s Oyster Restoration Update, Chesapeake Bay Program partners have constructed 539 acres of oyster reefs toward restoring five tributaries in Virginia. In 2019, partners constructed an additional 94 acres of oyster reefs.

  • Lafayette River: Initial oyster restoration work was completed in 2018 with 80 acres restored, making it the first Virginia tributary to be considered complete under the ten tributaries outcome. Of the 80 acres, 70 acres met the criteria to be considered restored due to older existing restoration projects (22 acres) and historic reefs (48 acres). The project is now in the monitoring phase.
  • Lynnhaven River: Prior to 2019, an estimated 91 acres of existing oyster reefs had been restored or were functioning at a restored level. In 2019, an additional 14 acres of reef were constructed in the Broad Bay and Humes Marsh areas bringing the total to 105 acres restored toward the 152-acre goal.
  • Piankatank River: The Piankatank River restoration plan calls for 438 acres of reefs to be restored. Of this total, 203 acres already met the definition of a restored reef. In 2019, partners built 47 acres of reefs, bringing the total to 317 restored acres. Plans are in place to construct at least 33 acres in 2020.
  • Lower York River: In 2019, partners constructed 33 acres using fossil shell material. To date, 35 acres of reefs have been restored toward the 200-acre goal.
  • Great Wicomico River: Partners are working to develop a restoration plan, expected to be completed in 2020.

Large-scale oyster restoration is a shining example of what can happen when many partners work together. To date, partners have invested more than $62 million in oyster restoration in Chesapeake Bay tributaries over the past nine years. Funding comes from a variety of sources, including federal, state and local governments, as well as non-profit organizations. The Maryland and Virginia Oyster Restoration Interagency Team is made up of representatives from the National Oceanic and Atmospheric Administration, U.S. Army Corps of Engineers, Oyster Recovery Partnership, Virginia Marine Resources Commission and Maryland Department of Natural Resources, among others.

To learn more about our progress toward restoring oyster habitat and populations in ten Bay tributaries, visit www.ChesapeakeProgress.com.



Chesapeake Bay Program

Hi Robert, we're glad that you're interested. Pages 15-16 of the following Oyster Reef Monitoring Report show the proportion of reefs that are meeting our target oyster density criteria and our minimum threshold density to be considered successful. Additional information in the report may be useful to you as well! https://www.chesapeakebay.net/documents/2018_Maryland_oyster_monitoring_report_final_v2_Part1.pdf

Robert A Cunningham

I would like to know how successful the restoration has been can you publish the estimated number of oysters growing each year for each location, starting before the project started up to present date.

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