In the next month or so, the Chesapeake Bay will celebrate something big: the completion of the large-scale oyster restoration of the Manokin River. The Manokin, just south of Deal Island on Maryland’s Eastern Shore, is the final puzzle piece of the Chesapeake Bay Partnership’s full restoration of 10 tributaries (five in Maryland and five in Virginia).
The other tributaries restored in Maryland include Harris Creek, the Little Choptank, Tred Avon, and St. Marys rivers, and in Virginia the Lafayette, Piankatank, Great Wicomico, Lynnhaven, and Lower York rivers. The goal was to complete these restorations by 2025, and now that goal is about to be met in a major success for Bay advocates. Virginia even added a “bonus” tributary, the Eastern Branch of the Elizabeth River, bringing the total to 11 rivers and a total of 2,224 acres (2.76 square miles) of Bay habitat successfully restored. That makes this project the largest oyster restoration initiative in the world.
As oyster restoration partners race to the finish line, the people responsible for supplying and planting the oysters on the 441-acre Manokin reef must work in harmony, and conditions must be just right. Chesapeake Bay Magazine had the chance to visit the Oyster Recovery Partnership’s shell recycling facility at Horn Point in Cambridge, along with the University of Maryland Center for Environmental Science (UMCES) Horn Point Oyster Hatchery, where all the pieces come together.
The Oyster Recovery Partnership (ORP), collects old oyster shells to recycle for new oyster habitat. ORP runs an operation at Horn Point cleaning and preparing the shells for baby oysters to attach to. At the same time, the baby oysters themselves are being raised at Horn Point’s oyster hatchery. Both efforts are necessary to complete the Manokin River sanctuary.
At ORP’s outdoor shell processing area, shells are piled high above my head. ORP Director of Field Operations estimates one pile alone holds 65,000-70,000 bushels of shell. The shells come in by tractor trailer 750 bushels at a time. They are purchased from shucking houses in Virginia with state funding, or recycled from restaurants and individuals. After the shells are dried out for a year, they are washed with Choptank River water and tumbled continuously until they’re clean. “For every day of oyster planting, there’s a day of washing,” King tells us.
Just a short walk away in the oyster hatchery, lab workers are busy painstakingly breeding and growing microscopic oyster larvae, first in small plastic bins, then in a series of large, 10,000-gallon tanks.
For breeding, hatchery employees and interns use oysters specially harvested for the purpose by watermen. Each oyster individually spawns in a small tank of flowing water, where the hatchery marks each tank as male or female and collects the sperm and eggs they release. They manually fertilize the eggs with the collected sperm, and the successful larvae swim around eating a special diet of nutrients created in the hatchery’s “greenhouse”.
When the larvae start maturing, they grow a foot, secrete glue, and look for an appropriate surface to attach to. That’s where ORP’s recycled shells come in. Several larvae can attach to one recycled adult oyster shell. They begin to grow into juvenile oysters, where they’ll become strong enough to survive on a protected reef when oyster restoration partners boat them out to plant them.
It takes a series of exacting steps to get oyster eggs and sperm to become fully functioning oysters, and it doesn’t always work. The success rate of oyster reproduction is extremely low in the wild, usually less than 1%. In the hatchery, it varies between about 10% and 25%.
Stephanie Alexander, the UMCES Oyster Hatchery director, says that because the hatchery relies on the nearby Choptank River for the water they use, salinity levels can have a big impact on production. While they’d like the water salinity to be around 12-13 parts per million (ppm), this year, salinity is just below 10 ppm. With rainfall controlling salinity, the watershed affects Alexander’s efforts greatly. For example, the salinity in 2019 was only 5 ppm, on the heels of record-breaking rainfall and water flow in the Bay. Production was low. On the other hand, “drought years are saltier and give great production,” she points out. In 2023, a salty year, the hatchery was able to produce 1.6 billion baby oysters.
While the hatchery produces baby oysters for private aquaculture businesses as well as for restoration, Alexander says about 75% of their efforts this year have gone to the Manokin project. She says she is cautiously optimistic that Horn Point will be able to produce the rest of the oysters needed to complete the project. “We are working hard to produce oysters and trying to deal with all of the challenges that are thrown our way.”
When the Manokin restoration is complete and the goal of the 2014 Chesapeake Bay Watershed Agreement is officially met, many wonder what will be next for oyster recovery.
The focus will shift to new tributaries, like Herring Bay, the Nanticoke River, and Hooper Strait. The Chesapeake Bay Program is working on a revised Watershed Agreement that will include a proposed Oyster Outcome. The Watershed Agreement draft and the oyster proposal are still open for public comment through Monday, Sept. 1, by emailing [email protected].
