Oyster Reef Restoration in the Chesapeake Bay: We're Making Significant Progress

Why we’re restoring Chesapeake Bay oyster reef habitat 

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NOAA and our partners are working to restore oyster reef habitat in the Chesapeake Bay because oysters are an important part of the ecosystem. They grow in reefs that provide habitat for a number of Bay species. Oysters are filter feeders, so they clean the water as they eat. Oysters support not only the ecosystem, but also the economy. Areas with healthy oyster reefs are great for commercial and recreational fishing. 

But due to disease, overfishing, degraded water quality, and other issues, only about 1 percent of the native oyster population remains. To help restore reefs, we are working as part of the Chesapeake Bay Program effort to restore oyster reefs to 10 Chesapeake Bay tributaries by 2025. This goal was set in the Chesapeake Bay Watershed Agreement. We lead the Maryland and Virginia workgroups that plan and implement restoration. 

Our scientists map potential restoration areas and track the progress of restored reefs. They also identify reefs in the tributaries that can already be described as healthy and restored. For each of the tributaries selected for restoration, the partners develop a “restoration blueprint.” It details precisely where reefs will be built, and whether spat-on-shell (juvenile oysters) need to be added. And we provide funding that helps hatcheries create baby oysters that are planted on restoration sites. 

While there’s a lot of good news, the large-scale oyster restoration effort faces some challenges. Oyster shell is in high demand and low supply for use in oyster restoration, aquaculture, and wild harvest sectors. Most reefs are built using alternative materials such as stone. But hatcheries still need oyster shells to produce juvenile oysters (spat-on-shell). Partners are exploring alternatives under an initiative led by the Oyster Recovery Partnership.

Every year, the restoration team compiles statistics on how the effort is going. Overall, the goal is to restore reefs in 10 tributaries, and so far, we have hit our targets in eight of those 10. Below are some details and statistics (as of the end of 2023) about each of the tributaries where we’re working on restoration projects.

Chesapeake Bay-wide updates

NOAA and our partners in the Chesapeake Bay Program have restored oyster reefs in eight of 10 tributaries selected for restoration work. Once those 10 tributaries are complete, they will include 2,334 acres of healthy reef. 

Before the team started active restoration work, they identified 506 acres of existing healthy reef that could be classified as restored. The partners have restored an additional 1,572 acres (183 in 2023). There are 256 acres that still need to be restored to meet the total target set in the 10 restoration blueprints. The remaining acres are in the Lynnhaven (Virginia) and Manokin (Maryland) rivers.

Progress in Maryland

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We and our partners selected five tributaries in Maryland for large-scale oyster reef restoration. An Oyster Restoration Blueprint was developed for each tributary to guide restoration there. Our team of partners has completed restoration work in four Maryland tributaries: Harris Creek and the Little Choptank, Tred Avon, and St. Mary's rivers. In-water restoration work in the Manokin River started in 2021. 

Plans are for a total of 1,332 acres of oyster reef in Maryland thanks to these large-scale restoration efforts. So far, there are 1,110 acres across all five tributaries. That’s more than 1.5 square miles—more than 800 football fields—of reefs in Maryland alone. 

Our partners constructed these reefs using one of two methods: by building a substrate base followed by planting with hatchery-produced oyster seed, or by placing only seed onto remnant reefs. Through the end of 2023, our team has planted 6.85 billion oyster seed in Maryland as part of the effort. Total cost to date is approximately $87.36 million. 

Monitoring results show strong success relative to preestablished success criteria, with 99 percent of 6-year-old restored reefs meeting at least the minimum threshold oyster density and biomass. Eighty-three percent met the higher target density and biomass. 

In 2020–2023, Maryland saw above-average natural oyster spat sets levels. Notably, there were particularly abundant spat sets in the St. Mary’s River in 2022 and in the Tred Avon River in 2023. The Tred Avon has historically had spat sets lower than other Maryland tributaries, so it’s good news to have above-average recruitment there. These trends bode well for the longer-term success of the restored reefs. 

2023 was a record-setting year for Horn Point hatchery oyster larvae production. This meant that partners were able to plant 1 billion seed oysters in Maryland. 

We work on these projects with partners:

• U.S. Army Corps of Engineers
• Maryland Department of Natural Resources
• Oyster Recovery Partnership

Harris Creek

In Harris Creek, there are now 343 acres of healthy oyster reef. Our partners planted 2.49 billion oyster seed there. The total restoration cost was $28.37 million.

Initial restoration work was completed in Harris Creek in 2015, followed by several years of planned second-year-class oyster plantings where needed. Oyster partners completed restoration work (reef construction and seeding) following the Harris Creek Restoration Blueprint, and monitored the reefs at three and six years after restoration. This is the first tributary in the  Bay to pass that milestone. At 6 years of age, all but 5 of the 348 restored acres met the Oyster Metrics success criteria. Monitoring results show strong success relative to the pre-established success criteria.  

Little Choptank River

This project features 358 acres of oyster reef; oyster restoration partners planted 2.09 billion oyster seed here. The oyster restoration effort cost is $28.17 million.

Initial restoration work in the Little Choptank River started in 2014 and was completed in 2020. Work in 2023 focused on reef monitoring, and on implementing the scheduled supplemental oyster seedings called for in the Little Choptank River Restoration Blueprint. On reefs where monitoring showed oyster densities and biomass higher than projected, we did no additional seeding. On reefs where densities and biomass were as projected, or lower, the team implemented additional seedings. We evaluated reefs to determine if they meet other oyster metrics success criteria, including presence of multiple year classes and reef structural integrity. Monitoring to date shows that virtually all reefs are meeting the established success criteria.

Tred Avon River

There are 130 acres of oyster reef in the Tred Avon River as part of this project. The oyster restoration team planted 1.17 billion oyster seed here. The total cost of this restoration is $12.11 million.

Initial restoration work in the Tred Avon River started in 2015 and was completed in 2021. Work in 2023 focused on reef monitoring and on implementing the scheduled supplemental oyster seedings called for in the Tred Avon River Restoration Blueprint. On reefs where monitoring showed oysters densities and biomass higher than projected, these seedings did not happen. On reefs where densities and biomass were as projected, or lower, partners implemented additional seedings. 

We evaluate reefs to determine if they meet other oyster metrics success criteria, including presence of multiple year classes and reef structural integrity. Monitoring to date shows that more than 85 percent of the restored reefs monitored are meeting at least the minimum threshold oyster density and biomass success criteria. 

St. Mary’s River

The St. Mary’s River includes 60 acres of oyster reefs thanks to this project. Oyster partners planted 151.1 million oyster seed here. The total cost of restoration is $1.55 million.

Initial restoration work in the St. Mary’s River started in 2021 and was completed in 2022. Partners have restored 25 acres of reefs in the river. These restored reefs, in addition to the existing 35 acres of healthy reefs, bring the total to 60 acres, as called for in the St. Mary’s River Restoration Blueprint. Future work will focus on second-year-class seedings, as needed, per the St. Mary’s River Restoration Blueprint. We will also monitor reefs per the Oyster Metrics success criteria. The first three-year monitoring is scheduled for fall 2024. 

Manokin River

So far, our team has restored 219 acres of oyster reef as part of the Manokin River project. There are still 222 acres to be restored to bring the total to 441 acres. So far, partners have planted more than 948 million juvenile oysters. The cost so far is $17.17 million. 

The Manokin River Restoration Blueprint sets a goal of restoring 441 acres of reefs in the river. In-water restoration work started in 2021. In 2023, partners initially restored 174 acres of reefs in the river with spat-on-shell. In addition, Murtech Inc., under contract from the Maryland Department of Natural Resources, constructed a 12-inch-high stone base on nearly 103 acres in the river. The stone-base construction work will continue in 2024, when Murtech, Inc., will complete the remaining approximately 8 acres of planned stone-base reef construction. These stone-base reefs will be seeded with spat-on-shell over the next few years. This river requires the largest number of acres to be restored of any of the 10 tributaries Bay wide slated for restoration. Restoration work here will likely take until the end of 2025.

Progress in Virginia

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Oyster restoration partners selected five tributaries in Virginia for large-scale oyster reef restoration. The team developed an Oyster Restoration Blueprint for each tributary to guide restoration there. Restoration work in four Virginia tributaries—the Lafayette, Piankatank, Great Wicomico, and lower York rivers—has been completed. Restoration work is under way in the Lynnhaven River. 

There are 968 acres of oyster reefs in Virginia that are part of these projects. Partners in Virginia are so eager to restore reefs, they also have restored the Eastern Branch of the Elizabeth River, which is considered a “bonus” restoration tributary. 

There are still 34 acres remaining to be restored to get to Virginia’s original goal of 1,002 acres. So far, partners have spent $21.04 million on these efforts. 

Virginia has experienced consistently high annual natural spat sets since 2019. This has bolstered shell volume and the number of larger oysters on restored reefs. This is the case for harvest reefs in Virginia, too.

There were some issues with construction material and locations of 13 acres of restoration reefs in the Lynnhaven River. Agencies and organizations are discussing ways to handle these reefs. They may end up being removed. This makes constructing the other planned reefs even more important for completing restoration work in the river.  

In Virginia, our partners include:

• U.S. Army Corps of Engineers
• Virginia Marine Resources Commission
• Virginia Institute of Marine Science
• Chesapeake Bay Foundation
• Christopher Newport University
• City of Norfolk
• City of Virginia Beach
• Elizabeth River Project
• Lynnhaven River NOW
• National Fish and Wildlife Foundation
• The Nature Conservancy
• The Pew Charitable Trusts
• Pleasure House Oysters/Ludford Brothers Oyster Company
• Virginia Commonwealth University 

Lafayette River

There are 82 acres of oyster reef in the Lafayette River through this project. The cost was $716,000.

Planned oyster restoration work in the Lafayette River Restoration Blueprint wrapped up in 2018. It was the first river in Virginia to be considered complete toward the Bay-wide goal to restore reefs in 10 tributaries by 2025. Scientists now are monitoring the restored and existing reefs in the river. Earlier restoration projects show high densities of oysters representing numerous year classes, which bodes well for the newer Lafayette reefs. 

In 2022, the Virginia Institute of Marine Science conducted bathymetric and video surveys of three restored reefs in the river. The two largest reefs exceed the oyster metrics success targets for biomass and density, while the third met threshold criteria. Since 2018, the Elizabeth River Project has continued to coordinate the construction of shoreline oyster restoration projects through its partnership with the U.S. Navy’s Lafayette Annex and waterfront residential property owners. This is above and beyond the 82 acres already restored.

Piankatank River

There are 497 acres of oyster reef in the Piankatank through this project, which exceeds the original goal of 444 acres. The total cost is $11.1 million.

Oyster reef restoration work was completed in the Piankatank River in 2021, per the Piankatank River Restoration Blueprint. The U.S. Army Corps of Engineers’ Norfolk District, with the Virginia Marine Resource Commission, constructed an additional 53 acres of stone reefs in the Piankatank River in 2023. 

Great Wicomico River

There are 124 acres of oyster reef in the Great Wicomico through this project. The total cost is $907,000.

The oyster restoration team completed work in the Great Wicomico River in 2021, per the river’s Restoration Blueprint. The U.S. Army Corps of Engineers’ Norfolk District, in partnership with the Virginia Marine Resources Commission, has begun planning efforts to perform adaptive management on existing reefs in the Great Wicomico River. Efforts include:

• Raising some reefs that were constructed back in 2004 to a higher elevation
• Placing habitat stones on areas prone to degradation
• Expanding the footprint of an existing reef

They will finalize designs in 2024, and construction is estimated to begin in 2025.

Lower York River

There are 204 acres of oyster reef in the lower York River through this project—four more than the original blueprint goal. Total cost is $5.71 million.

In 2023, the Virginia Marine Resources Commission constructed nearly nine acres of new stone reefs in the lower York River. This work, combined with intensive reef construction in 2022, surpassed the Lower York Restoration Blueprint goal of 200 acres of reefs. This means restoration in the river is now complete, making it the fourth of five planned Virginia tributaries. Future efforts will focus on monitoring to ensure these reefs are meeting established Oyster Metrics success criteria.

Lynnhaven River

There are 114 acres of oyster reef in the Lynnhaven through this project. There are 38 acres remaining to hit the Blueprint goal. The cost to date is $2.62 million.

The Lynnhaven River Restoration Blueprint sets a goal of 152 acres of reefs in the river. In 2022, the Chesapeake Bay Foundation and Lynnhaven River Now constructed three reefs totaling 13 acres. Due to issues with the construction material and reef locations, these reefs are now under consideration for mitigation efforts, including possible removal. As of 2022, these reefs are not being counted toward the restored acreage in the Lynnhaven River. 

The partners have restored 25 acres of reefs in the river. The U.S. Army Corps of Engineers’ Norfolk District partnered with the City of Virginia Beach to award a contract in 2023 to Coastal Design & Construction, Inc., to construct 23.2 acres of new reefs in the Lynnhaven River. These reefs will be constructed to a max height of 1 foot using 6 inches of size-1 crushed stone and 6 inches of fossil shell. The contractor plans to begin reef construction in fall 2024. 

Recent monitoring on an 8-acre reef constructed in 2021 by U.S. Army Corps of Engineers’ Norfolk District, consisting of more than 28,000 reef balls. The reef far exceeds oyster metrics target success criteria for oyster density and biomass.

What’s next for oyster restoration in the Chesapeake Bay

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Things are looking good for the partners to meet their goal of restoring healthy oyster reef habitat in 10 Chesapeake Bay tributaries by the end of 2025. But there’s so much more we can do to support oysters in the Chesapeake—and in turn the ecosystem and economy that benefit when there are more oysters in the Bay. You might be able to help by being an “oyster gardener” if you live in Maryland or Virginia. Because oysters thrive in a healthy ecosystem, we can all help by making simple changes to help protect the Chesapeake.

Chesapeake Bay Program partners, including NOAA, are currently working on defining what their goals for the future beyond 2025 are. The oyster restoration partners are eager to continue their work, helping to bolster oysters for habitat restoration, aquaculture, and the wild fishery. They are also interested in exploring how oyster restoration and other kinds of habitat restoration can work together. For example, is it better for everyone if oyster reefs and submerged aquatic vegetation are encouraged to thrive near each other? We’re also looking at how oyster reefs can support community resiliency in the face of climate change. 

Shell is ready to be planted in a restoration project. Photo: Virginia Marine Resources Commission.