Restoring Oysters and Water Quality to Great Bay

Restoration project largest of its kind north of Chesapeake Bay

Portsmouth, NH | June 24, 2014

Beginning today, The Nature Conservancy - along with partners at the University of New Hampshire - are working in the waters of the Great Bay estuary constructing 2.5 acres of oyster reef in an attempt to restore the once abundant shellfish to a natural system stressed from a number of factors including loss of habitat and increased nitrogen levels.  

Vast reefs of live oysters once covered the bottom of the Great Bay estuary, filtering out excess nutrients, providing essential habitat to a diversity of fish, and offering recreational harvest to generations of locals.  But due to disease and past over-harvest, the estuary suffered a near collapse of its native oyster population - losing more than 90% of historic reefs. 

“The restoration of oysters may be Great Bay’s best hope for a sustainable recovery of the estuary” said Dr. Ray Konisky, The Conservancy’s Director of Marine Science. “These resilient animals are amazing natural water filters – with mature reefs having the ability to naturally remove tons of nitrogen annually from the system. We feel strongly that oyster restoration is a natural solution that will help bring the Bay back into balance.” 

Over the next several days, marine scientists from the two organizations will be working alongside local marine contractors Riverside & Pickering and Granite State Minerals to place more than 240 tons of dried, recycled surf clam shell on the estuary channel bottom in arranged plots.  This layer of shell acts as the foundation for the living reef.  Later this summer, more than a half a million disease-resistant oysters raised at a UNH laboratory by Dr. Ray Grizzle, will be placed on the newly constructed reef.  The reef will be monitored to measure oyster growth, habitat restoration and overall reef success. 

“We want to complement efforts being made by communities and individuals across the watershed who are investing in meaningful nitrogen reduction efforts,” continued Dr. Konisky. “The Nature Conservancy is committed to working with partners to drastically scale-up these activities in order to reach our long-term goal of 100 acres of restored reef in the estuary. Building this natural infrastructure will have dramatic, long term benefits for the natural system, and is a common sense solution that will assist our communities in meeting their nitrogen reduction goals.”     

This year’s construction extends New England’s largest oyster restoration project into a sixth consecutive year, with over 13 acres and more than 3 million adult oysters restored to Great Bay since 2009. The reefs are constructed in areas closed to harvest so that they can act as “spawner sanctuaries” for the rest of the estuary. 

Funding for oyster restoration comes from a variety of federal, state, and private sources.   Lead funders include the Piscataqua Region Estuaries Partnership (PREP), National Oceanic and Atmospheric Administration (NOAA) Restoration Center, The NH Department of Environmental Services, and many private and community minded donors.

For more information about reef construction visit


High resolution images are available upon request.

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world's toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at unprecedented scale, and helping make cities more sustainable. Working in more than 65 countries, we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.

Contact information

Jim O'Brien
Director of External Affairs
The Nature Conservancy
22 Bridge Street, 4th Floor
Concord, NH 03301


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