Ecological Restoration

Oysters are currently at less than 1 % of historic abundance due to disease related mortality, habitat degradation, reduced water quality, and harvest pressure. Based on recent scientific review of restoration alternatives for the native oyster in Chesapeake Bay, the ecological restoration team works with our many partners using a targeted approach to optimize ecological benefits and population recovery while minimizing costs. We work closely with our partners to rehabilitate degraded habitat using dredged shell and/or alternative substrates, to improve bar quality by performing targeted dredging, and to target the planting of disease-free hatchery oysters produced by our Piney Point Aquaculture Facility and the University of Marylandís Horn Point Hatchery. Please explore this page to learn more about our restoration activities.


2013 Oyster Restoration Progress in the Choptank Complex

Implementation Update: Harris Creek, Little Choptank River, and Tred Avon River


Little Choptank River Oyster Restoration Open House

Thursday, February 27, 2014 - 3-8 p.m

Little Choptank River Oyster Restoration Presentation


Tred Avon Oyster Restoration

More information about the Tred Avon Oyster Restoration

Draft Tred Avon Restoration Plan


Harris Creek Oyster Restoration

More information about the Harris Creek Restoration Project.


Maryland's 10-Point Oyster Restoration Plan

In order to achieve our oyster restoration goals, the State of Maryland is following a comprehensive 10-point restoration plan. Many facets of the plan have already been implemented and are ongoing, while others, such as those pertaining to aquaculture and new sanctuaries, are relatively new. The plan is outlined here, with more detail provided for items pertaining directly to restoration. You may download a slideshow about the restoration plan here.


  1. Focus on targeted restoration strategies
  2. Expand the sanctuary program
  3. Support a more targeted and scientifically managed wild oyster fishery
  4. Shift commercial production to aquaculture
  5. Rehabilitate oyster bar habitat
  6. Manage against oyster disease
  7. Increase hatchery production
  8. Enhance law enforcement
  9. Increase citizen involvement
  10. Integrate inmate labor

Targeted Restoration

Maryland is implementing multiple strategies for native oyster restoration using a targeted approach. We will set goals to maximize ecological benefits, facilitate population recovery and create positive outcomes for the commercial oyster fishery. Because some of these goals may conflict, we will target specific areas for each restoration goal.


(Click to Enlarge)

We combine recent bottom survey data with historical oyster bar locations to help determine the best sites for rehabilitation. Knowing the average salinity in a tributary allows us to select a restoration alternative that appropriately addresses disease and recruitment issues at each site. Although successful recruitment occurs in higher salinities, oysters there are subject to greater disease pressure. Conversely, oyster populations in lower salinities are recruitment-limited but benefit from the inability of disease-causing organisms to flourish there. Many partners, such as the Maryland Geological Survey and the Oyster Recovery Partnership, are involved in completing any one project. The flowchart at left is a simple, ecologically-based representation of the process.


Oyster Bar Rehabilitation

One key limiting factor for native oyster population recovery is the amount of suitable bottom habitat on which oyster larvae can settle. Approximately 90% of oyster habitat has been lost during the past 25 years, resulting in the need to rehabilitate at least 10,000 acres of habitat to facilitate large-scale recovery.


The True Cost of Rehabilitation
Depending on the method chosen, rehabilitation costs can range from $2,000 to $100,000 per acre. To date, the State of Maryland has spent $2.3 million in capital funds to design, coordinate, and implement oyster bar rehabilitation. In the process, 600 watermen were provided with work opportunities. The total yield thus far from these expenditures has been 250 acres of rehabilitated oyster reef.

Facing a Shell Shortage
Oyster shell, either new (shucked) or from buried deposits, is the predominant and preferred cultch for oyster habitat projects in the Bay. Since 1960, the dominant source of shells for restoration has been dredged shells from buried deposits in the Upper Bay; however, improving degraded oyster habitat across large areas will require more shell than is available from traditional shell deposits. To obtain sufficient cultch for upcoming restoration projects, Maryland has obtained a permit for a reclamation program that would provide up to 25 million bushels of shell. Also pending is a shell dredge permit application to obtain up to an additional 5 million bushels of shell from Man O'War shoal.

Alternative Substrates
The most feasible function of alternative substrates is to provide a firm base for constructed oyster bars. Alternate materials that replace the need for natural shell and can be economically manufactured in large quantities have not yet been identified.

Oyster Hatcheries

In order to meet the demands of an aggressive rehabilitation agenda, a rapidly growing Marylanders Grow Oysters program and a new commercial aquaculture initiative, Maryland must have access to large quantities of disease-free oyster larvae (up to 2 billion per year) for restoration and distribution. To this end, the Maryland DNR has done the following:

  • Established a new Memorandum of Understanding with the University of Maryland Center for Environmental Science (UMCES) for future hatchery production;
  • Purchased all available oyster shells from shucking houses in the state and transported them to the UMCES Horn Point Hatchery for 2011-2012 production;
  • Supported legislation that increased the price paid per bushel of oyster shell from $.25 to $.50;
  • Initiated oyster production at its own Piney Point Aquaculture Facility in St. Mary's County. Approximately 50 million oysters were produced there in 2009.