Building a Future for the Chesapeake's Oysters

By Tom Pelton and Bill Goldsborough
Published in the Fall 2010 issue of Save The Bay magazine

For centuries, a vast network of oyster reefs fed the Chesapeake Bay's people, cleaned its waters, and protected its fish and crabs. But by the 1920s, dredging had removed three-quarters of the Bay's life-giving reefs. The survivors were nearly eradicated in the second half of the 20th century by disease, pollution, and overharvesting.

Today, however, there are important new reasons for hope for the Chesapeake Bay's keystone species. On July 6, 2010, the Chesapeake Bay Foundation (CBF) released its report, On the Brink: Chesapeake's Native Oysters—What it Will Take to Bring Them Back. Covered by more than two dozen TV stations and newspapers, reaching more than a half-million people, the report detailed reasons for hope and laid out the next steps needed to restore oyster populations.

  • A bold new oyster sanctuary program is being proposed in Maryland that provides the essential next step to oyster recovery.
  • Recent research shows that oysters are developing resistance to once-devastating diseases, especially in the southern Bay.
  • Oyster aquaculture is booming, providing new avenues to bring shellfish back and stimulate the Bay region's economy.
  • And, finally, the federal government is considering the ambitious goal of restoring self-sustaining oyster populations in 20 Chesapeake tributaries by 2025.

Oysters are of paramount importance because they are a vital organ necessary for the Bay's ecological and economic health. Each adult oyster filters and cleans up to 50 gallons of water per day. Over the last three decades, Maryland and Virginia have suffered more than $4 billion in cumulative annual losses because of the decline of oyster-related industries.

To research the report, CBF interviewed more than a dozen leading oyster scientists, reviewed numerous scientific journal articles and reports, and reached these conclusions about the state of oysters in the Bay:

Growing Disease Resistance

Research suggests the increased prevalence of oyster diseases in recent decades is driving a natural selection process that is breeding tougher oysters, especially in the southern Bay where the diseases are more common. In Virginia's York River fewer than five percent of oysters are dying from MSX today, while more than half were dying of the disease a decade ago.


Maryland is proposing to more than double its oyster sanctuaries, to protect 9,000 acres (or 25 percent) of the Bay's remaining reefs. A committee of experts in Virginia also has recommended an expansion of no-harvest zones. These sanctuaries are critical because they guard reefs that act as breeding grounds not only for oysters but also fish, crabs, and other life forms. Sanctuaries allow maximum reproduction of oysters, which helps the bivalves adapt to disease and other challenges and repopulates nearby harvest bars.


A problem that crippled smaller and more scattered sanctuaries created earlier in Maryland was "rampant theft of oysters in all areas of the state's waters," according to a state report. To protect its new sanctuaries, Maryland plans to increase electronic surveillance and pursue heavier penalties. A blue ribbon panel in Virginia also recommends stronger enforcement.

Habitat Reconstruction

A major obstacle to the return of oysters—even if they evade harvest and disease—is a lack of hard Bay bottom for the bivalves to grow on. Building elevated reefs with old shells appears to be succeeding. For example, in Virginia's Great Wicomico River, more than 180 million oysters are reported to be growing and thriving on reconstructed reefs. Key lessons learned from this project include the necessity of building up the bottom with old shells so that oysters are elevated out of the silt, and creating enough reef acreage to make reefs self sustaining through reproduction.

Water Pollution

Yet another hurdle for oysters is pollution. Silt and sediment washed off the land by rain can bury oyster beds. And even moderately low oxygen zones that do not kill oysters outright increase the susceptibility of oysters to Dermo disease. For these reasons, federal and state government efforts to control nitrogen, phosphorus, and sediment pollution are important for the recovery of oysters.


In Virginia, aquaculture is growing fast, with the number of oysters produced multiplying 10-fold over the last five years. To encourage underwater farms, Maryland recently rewrote its laws and will now allow leasing on 95,524 acres of oyster bars.

To bring back a healthy network of reefs, CBF has concluded the Bay states and federal government must take the following additional steps.

  • Approximately 40 percent of the Bay's historical reef acreage should be protected with sanctuaries and rebuilt with shells or other hard material.
  • The states should transition from a wildharvest oyster fishery to aquaculture by continuing to encourage oyster farming, which has tremendous potential for reviving the region's shellfish industry.
  • Both Maryland and Virginia should boost law enforcement to keep poachers away from no-harvest areas and oyster farms.
  • Most importantly for all life in the Bay, Congress must approve the Chesapeake Clean Water Act, which would provide financial incentives to states to follow plans to reduce water pollution and authorize more than $2 billion for cleanup projects.

There is still hope for the Chesapeake's oysters. But without these steps, we risk the permanent loss of not only the Bay's shellfish, but also its health, identity, economy, and greatness.

Read CBF's 2010 report on rebuilding oysters in the Chesapeake Bay.

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Founded in 1967, the Chesapeake Bay Foundation (CBF) is the largest independent conservation organization dedicated solely to saving the Bay.

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