A new oyster restoration strategy envisions bringing back vibrant, self-sustaining populations of the beleaguered bivalves through large restoration projects — typically hundreds to thousands of acres in size — in tributaries around the Bay.
The Native Oyster Restoration Master Plan, the first-ever Baywide oyster strategy, acknowledges that the goal is lofty and could cost billions of dollars.
But the plan, developed by the Army Corps of Engineers with other federal and state agencies as well as nonprofit organizations, said the new large-scale restoration approach was needed because of the poor track record of past projects.
Those efforts had "proved challenging" at least in part because they were scattered around the Bay and were often too small to become self-sustaining.
"The master plan provides a science-based comprehensive oyster restoration plan for Chesapeake Bay oysters," said Susan Conner, project manager for the Corps' Norfolk District. "This plan is ambitious but warranted given the current state of oysters and their habitat in the Bay."
Oysters were once a critical part of the Bay ecosystem, covering hundreds of thousands of acres with their reefs and clearing the water by filtering huge amounts of algae from the water.
As the result of overharvesting, the devastating impact of two oyster diseases, loss of habitat and degraded water quality, populations today are thought to be at 1 percent or less of their historic level and their habitat is being lost at an alarming rate. According to a recent estimate, oyster habitat decreased 70 percent from 1980 through 2009.
To reverse that trend, the plan calls for large-scale restoration projects to take place in sanctuaries where oysters would be protected from harvest.
The goal of each project would be to restore 20–40 percent of the historic habitat in a given tributary. Generally, the plan expects that restoration projects would include constructing 1-foot reefs of shell or alternate hard substrates and seeding them with spat, or baby oysters.
The hope is that this would create a "critical mass" of oysters capable of producing enough young oysters and enough new shell habitat to become self-sustaining. It's also hoped the oysters would develop resistance to MSX and Dermo, the diseases that have devastated the population in recent decades.
The plan identifies 24 locations — 14 in Maryland and 10 in Virginia — considered to be the best candidates to support large projects based on a variety of considerations such as their historic productivity, circulation patterns, salinity, water depth, water quality and other factors.
Not all of the identified sites are protected as sanctuaries, but Corps officials say there is no shortage of sanctuaries to support restoration projects in the next several years.
"I would love to have the problem in the future where we've restored everything identified as a sanctuary," said Angela Sowers, study manager for the Corps' Baltimore District. "Right now we have enough to work on before there is a need to revisit that issue."
The plan itself does not set a restoration goal, but it is considered a supporting document for the 2010 federal Chesapeake Bay strategy, developed in response to President Obama's 2009 Bay Executive Order. That strategy called for restoring oyster populations in 20 tributaries by 2025.
Restoration will require patience, Sowers said. Most projects would likely take several years to construct, and then require several more years of monitoring before biologists could determine whether they were a success or needed more work. "It definitely
is not going to be a very quick thing," she said.
The plan said the cost of restoring all 24 locations could range from $1.85 billion to $6.5 billion. Restoring 20 tributaries, as called for in the federal Bay strategy, would be slightly less: $1.56 billion to $5.38 billion.
But the plan said those numbers were "conservatively high" because it assumes every restored acre will need reef construction. In reality, some suitable habitat likely exists in some areas, the report said. The plan emphasized that the Corps "is not recommending an investment of this magnitude at any one time. Restoration should progress tributary by tributary."
Sowers said that lessons learned doing the first projects, which are generally the smallest, may help reduce costs later for the larger, most expensive projects.
Restoration sites are being selected by teams in each state that include state and federal agency representatives, scientists and representatives from nongovernmental organizations.
In Maryland, the first large-scale project was begun last year in Harris Creek, a tributary to the Choptank River. When completed in the next few years, the project is expected to cover more than 300 acres, making it the largest oyster restoration attempted in the Bay so far. The project could have a price tag of $30 million. (See "Harris Creek oyster project offers hope," November 2012)
The Little Choptank is expected to be the next Maryland project.
In Virginia, the initial efforts are expected to continue to focus on the Great Wicomico and Lynnhaven rivers where some projects have already taken place, Conner said. Future work may be directed toward the Elizabeth and Piankatank rivers.
In addition to setting the sites aside as sanctuaries, the plan said efforts will also be needed to protect the sites from poaching, which has taken a toll on past restoration efforts.
"Illegal harvests pose a major risk," the plan said. It said a third of the oysters placed in Maryland sanctuaries between 2008 and 2010 were removed by illegal harvests, according to recent estimates. Illegal harvests are also thought to have impacted a recent restoration project in Virginia's Great Wicomico River.
Another hurdle for restoration projects is the lack of hard substrate, the plan said. Too little oyster shell is available to construct the needed reefs, so suitable alternative material is needed.
Degraded water quality, caused by the runoff of sediment, nutrients and toxins from the land could also pose a threat to restoration efforts.
The Native Oyster Restoration Master Plan is available on the Chesapeake Bay Executive Order website: executiveorder.chesapeakebay.net/.
Tributaries & Restoration Target Range (in acres)
Severn River: (190–290)
South River: (90–200)
Lower Chester: River (500–1,100)
Lower Eastern Bay: (700–1,400)
Upper Eastern Bay: (800–1,600)
Lower Choptank River: (1,400–2,800)
Upper Choptank River: (400–800)
Harris Creek: (300–600)
Little Choptank: (400–700)
Broad Creek: (200–400)
St. Mary's River: (200–400)
Lower Tangier Sound: (800–1,700)
Upper Tangier Sound: (900–1,800)
Manokin River: (400–800)
Great Wicomico River: (100–400)
Lower Rappahannock River: (1,300–1,600)
Piankatank River: (700–1,300)
Mobjack Bay: (800–1,700)
Lower York River: (1,100–2,100)
Pocomoke/Tangier Sound: (3,000–5,900)
Lower James River: (900–1,800)
Upper James River: (2,000–3,900)
Elizabeth River: (200–500)
Lynnhaven River: (40–150)
Source: The Native Oyster Restoration Master Plan