Shellfish Rehabilitation Program works to restore quality oyster habitat

Oysters are an essential part of eastern North Carolina’s rich cultural heritage. Served raw, steamed, fried, roasted, or garnished, their rich, salty flavor is often celebrated around the state at weekend roasts and festivals. Not only do these rock-like mollusks provide excellent table fare, but they also offer many ecosystem benefits such as water filtration, shoreline stabilization, and habitat for different fish and other marine life.

Unfortunately, adult oysters are non-motile (meaning they cannot move on their own), which makes them particularly susceptible to extreme environmental conditions and habitat damage due to harvest. Low oxygen events, high harvest pressure, sedimentation, and fresh water from heavy rain, and hurricanes have all contributed to a large decline in oyster populations over the past 125 years.

Recognizing the value of oysters and the need for restoration, the North Carolina Division of Marine Fisheries and its partners have been investing incredible resources to rehabilitate oyster populations in North Carolina. Since 1905, the division has built thousands of high quality reefs on which oysters can thrive and reproduce. Today, division-led shellfish rehabilitation uses cutting edge science, collaboration with partners, and input from stakeholders to restore quality habitat on a scale that rivals any other effort in the nation.

The division’s approach to shellfish rehabilitation is twofold: build strategically placed oyster sanctuaries, which are protected from harvest, and construct open-access “cultch planting” areas to function more like natural reefs. These two reef building programs are intended to work with one another to offer our estuary high reproductive potential and plenty of suitable habitat for settlement and growth of oysters.

Oyster Sanctuaries

Oyster sanctuaries are specialized artificial reefs, purposely constructed to promote the restoration of oysters. The sanctuary concept is to build and protect densely populated, environmentally resilient oyster reefs. These productive sites supply the estuary with viable larvae for the benefit of other natural and cultch-planted reefs. The division began constructing oyster sanctuaries in the late 1990s and now manages 15 sanctuaries, each strategically placed to complement nearby cultch and natural reef sites. These large reef sites are built using specially-selected materials such as precast concrete structures, granite rocks, or fossil limestone. By constructing sanctuaries in this manner, they catch oyster larvae on their hard substrate and provide habitat for other shellfish and finfish. This year, the division and its partners constructed the third and final phase of the Swan Island Oyster Sanctuary, located near Point of Marsh on the southwestern section of Pamlico Sound. The 60-acre site was delineated in 2016 and construction occurred in 2017, 2018, and 2019. The reef has already displayed incredible resilience following hurricanes Florence and Dorian and now supports millions of healthy oysters in an area nearly the size of three college football stadiums!

Cultch Planting

As one of the division’s oldest initiatives, the cultch planting program is geared toward restoring habitat that functions more like natural reefs. Input from fishermen and extensive scientific data are used to pick suitable reef sites, which are then constructed by division vessel crews during the spring. Small, natural materials, usually oyster shell or fossil rock called “cultch,” are spread in a thin veneer on the bottom. The construction process is detailed and labor intensive, involving heavy equipment, large specialized vessels, and multiple staging areas along the coast. On deployment days, front-end loaders, conveyors, vessels, captains, biologists, deckhands, and operators all work together get the job done. Every year, crews deploy as much as 30 million pounds of cultch to build around 50 acres of habitat. Following construction, new sites are studied for a period of three years to monitor their success, which in turn helps guide site selection for future enhancements.

More Information

In recent months, the division has made a considerable effort to improve the availability of habitat information. If you would like to learn more about shellfish rehabilitation or see where reefs have been built, please visit the enhancement webpage and navigate to oyster sanctuaries or cultch planting. Interactive guides are available for both programs, each showing locations of sites, types and quantity of materials, years of construction, and in some cases side scan imagery from division surveys.

Enhancement webpage: http://portal.ncdenr.org/web/mf/habitat/enhancement

Artificial Reef Guide (with Sanctuaries): http://portal.ncdenr.org/web/mf/artificial-reefs-program

Cultch Planting Site Guide: https://arcg.is/1uWevj