Recycling oyster shells from restaurants not only provides reef habitat for new oysters and other fish, but it also benefits the marine economy and enables the mollusks to improve the environment by filtering water.
People in government and nonprofit organizations are rallying to create oyster habitats by collecting discarded oyster shells to return back into the water for baby oysters.
“Oysters are remarkable. They provide many benefits to the ecosystem they live in. They are filter feeders—they clean the water as they eat. And they grow in reefs, which provide great habitat for many other species. But in many places, their population has plummeted,” says the National Oceanic and Atmospheric Administration.
Today oyster habitats are threatened by water pollution, dredging, lost wetlands, diseases, overfishing and damaged reefs.
NOAA and other organizations are working to restore oyster habitats around the country. For example, the NOAA restoration center has provided grants to some 70 oyster rehabilitation projects in 15 states. Because oyster populations in the Chesapeake Bay have diminished due to disease, pollution, habitat loss, and overharvesting, its Chesapeake Bay office is helping groups in Maryland and Virginia restore oysters in 10 bay tributaries by the end of this year.
Environmental Benefits of Increasing Oysters in U.S. Waters
Found in salty or coastal waters, oysters clump together to live in shells, along piers and on top of rocks. Because they cluster together, oysters can create reefs and provide habitats for other marine life, including other fish. The reefs can also benefit the environment by preventing erosion along shorelines and creating protective barriers to deter storm surges during hurricanes.
Oysters are also known for their ability to clean water. One oyster can filter up to 50 gallons of water each day.
“The clearer, cleaner water can support plentiful underwater grasses, which—like the oyster reef—create a stable bottom and a safe, nurturing habitat for juvenile crabs, scallops, and fish,” NOAA says.
The Big Business of Oysters
Oyster sales in the United States during 2023 amounted to $326.9 million, according to the U.S. Department of Agriculture’s latest Census of Aquaculture. In fact, oysters accounted for the largest (56.8%) share of the $575 million in national mollusk industry sales that year—followed by clams (38.6%), mussels (3.9%), and abalone and other mollusks (both less than 1%).
In addition there were 900 oyster farms in the United States in 2023 compared to 701 in 2018. The states with the largest oyster farms were Massachusetts (191), Washington (116), Florida (92), Virginia (87), Maine (79), Maryland (45), Rhode Island (40) and New York (37). The USDA defines an aquaculture farm as a site where at least $1,000 worth of aquaculture products were produced, sold or distributed during the census year.
Oyster reefs also create communities for other types of fish that can be caught and sold as food.
North Carolina’s Hefty Investment Returns on Oyster Reef Restoration
The nonprofit North Carolina Coastal Federation, founded in 1982, works to restore the state’s coastline and is involved in oyster restoration. Receiving state and federal grants and other funding, the Coastal Federation has invested nearly $36.2 million during the last 12 years in its oyster sanctuary program to create several hundreds of acres of habitat for oysters. The habitat created is a network of no-harvest oyster reefs for larvae to reseed the wild oyster population and also support harvested oyster reefs. Commercial and recreational hook-and-line fishing is allowed there.
“Oyster populations, worldwide, are at record lows. Despite some recovery in recent years in North Carolina, it is estimated that oysters are at about 15-20% of historic harvest levels. Oyster harvest is currently the best measure of the oyster population in our state,” says the Coastal Federation. “In the state of North Carolina, it is illegal to dispose of oyster shells in landfills or use them as mulch for landscaping since they are needed for reef building in our sounds.”
Currently, the Coastal Federation has drop-off sites for recycled oyster shells at 3 regional offices and other locations in 10 counties.
“Every dollar invested in the program—regardless of its source—created a return on investment of $1.71 in economic and environmental benefits,” noted a Coastal Federation independent study released in 2024 called the “Economic Impacts of Oyster Sanctuaries: Key Insights (2013–2023).”
The study looked at $20 million invested by the state of North Carolina from 2013 for a 10-year period ending in 2023. Findings revealed that state investment supported 143 jobs generated $34 million in local business revenue. The state funding also yielded $8.7 million in employee wages/benefits plus $1 million in state and local tax revenue. Furthermore, the study noted the state spending for oyster habitats brought in $14.5 million in recreational fishing, $11 million in commercial fishing and $12.5 million in environmental services.
Commenting in February about the study was Stephanie Krug, a NOAA marine habitat resource specialist: “Investing in oyster reef restoration means investing in all of the benefits these reefs provide and the benefits of the restoration work itself. This report is vital in telling that story.”
In 2023, the Coastal Federation received a $14.9 million federal grant from NOAA’s Office of Habitat Conservation to increase by next year the oyster reef sanctuary to 500 acres. At the end of 2023, oyster sanctuaries had been created on 389 developed acres in North Carolina waters.
New Jersey Shell Recycling Program Wins Public Award
In May, members of the New Jersey Department of Environmental Protection’s Bureau of Marine Habitat and Shell Fisheries won the Governor’s Team of Excellence Award for the department’s shell recycling program. Started six years ago, the program has planted 240 tons of shells that have enabled 24 million baby oysters to live in Mullica River oyster reefs.
The program involves recycling oyster and clam shells from partner restaurants in Atlantic and Cape May counties. The shells are collected and cured for at least six months before being planted on oyster reefs. This effort removes discarded shells from landfills and provides materials for oyster habitats.
“With the recent acquisition of grant funding through NOAA’s Coastal Zone Management Program, the program continues to expand by partnering with new restaurants and installing public shell drop-off locations, thereby increasing the number of shells collected and recycled,” noted a media release about the award.
Shells are collected once a week and taken back for storage and curing. Every June and July, the shells are loaded onto a barge and taken to Mullica River oyster reefs. Then the staff uses high pressure water cannons to put the shells back onto reefs.
Repurposing Shells Offers Numerous Benefits
This recycling project with shells has multiple benefits for people and nature. At the same time, this effort can be replicated elsewhere to improve marine life and the blue economy.
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