|Oyster Restoration in Harris Creek|
Restorable bottom is hard bay floor in less than 20 feet of water that will support oysters.
Water Quality-Based on factors such as dissolved oxygen, temperature, salinity, nutrients, and water clarity. Oysters cannot survive if the water quality is very low.
Existing oyster reefs- Oyster reefs that were living in the area prior to our surveys. Many of these reefs are the result of substantial seed plantings by Maryland.
Restoration- To achieve restoration, each reef in the tributary should contain 50 oysters and 50 grams of dry weight/m2 over 30% of the reef, with at least two year classes (generations) surviving. One 3-inch oyster weighs about 1 gram. For the entire tributary to be restored, 50-100% of the restorable bottom must contain reefs that meet restoration requirements. The area must also cover 8-16% of the historic oyster footprint- area that oysters have historically inhabited.
Salinity - Amount of salt. Fresh water does not promote reproduction, while very salty water increases the risk of disease.
Spat-on-shell - Baby oysters growing on old oyster shells..
Circulation- The direction and strength of water flow. Oyster larvae will stay in the designated area to grow the population, and they also have the potential to settle in nearby tributaries, populating areas where oysters are harvested.
Projected placement, dispersal, and settlement:
Model created by Elizabeth North, USACE Baltimore District
Shell and oyster seed have been planted in Harris Creek for decades, and in September 2010, the State of Maryland declared Harris Creek an oyster sanctuary from which oyster harvest is prohibited. It was selected for restoration based on its sanctuary status as well as its salinity, water quality, circulation, and existing oyster reefs. The restoration process on this tributary is a large-scale collaborative effort involving several state and federal agencies, and guided by the draft Harris Creek Blueprint created by the Maryland Interagency Workgroup of the Sustainable Fisheries Goal Implementation Team.
Extensive mapping efforts were made by the NOAA Chesapeake Bay Office and the Maryland Geological Survey, and the U.S. Army Corps of Engineers (USACE) evaluated water quality and historic oyster bar location. These efforts found 600 acres of restorable bottom, and 300-600 acres are being targeted for restoration in accordance with USACE’s Native Oyster Restoration Master Plan. NOAA also commissioned an oyster population survey, which found that 19 acres currently meet the restoration targets. In 2011, Congress provided USACE $2 million for oyster restoration in Maryland that was used to construct 22 acres of oyster reef habitat in summer 2012 at seven sites in Harris Creek. Mixed shell (16 acres) and granite (6 acres) were used to make the reefs that will be seeded with spat-on-shell in summer 2012. These reefs will be periodically monitored, with a final evaluation performed after six years to determine if several year classes have survived and meet the restoration criteria.
How Close Are Oysters in Harris Creek to Being "Restored"?
Restored Acres in Harris Creek: Target and Completed
References and Further Information: