Oysters in Virginia

sailboats for dredging hauling dredged oysters onto boat
oysters used to be dredged with sailboats
Source: Popular Science Monthly, The Natural History of the Oyster (November 1874) and National Park Service,
Chesapeake Bay Gateways and Watertrails Network

A female oyster might release 20 million eggs in one spawning, but the vast majority will be eaten or land on a soft surface or shifting sand (where they die). After fertilization, young Eastern oysters (Crassostrea virginica) float for several weeks until they settle on the bottom of the bay, a tidal river, or along the Atlantic Ocean shoreline. The oyster larvae, in their pediveliger stage, use a "foot" to find a hard surface on which they can metamorphose into a juvenile oyster ("spat").

Once on a hard bottom as much as 25 feet deep, an oyster never moves from that spot again as it matures and grows for up to 20 years. If a storm carries a layer of sediment downstream, fish can swim to cleaner water until the sediments settle out. The oysters, trapped in one place on that same river bottom, will stop filtering food until the water clears. If the sediment cloud remains over the oyster bed for too long, oysters will die.

Shells of living and dead oysters gradually create a hard bottom in river estuaries or at the edge of the bay/ocean. As a result, areas where sediment flow may normally cover any bedrock may end up with a diverse pattern of hard substrate and muddy bottom, providing greater habitat options for plants and animals. Oyster bars have expanded, generation by generation, as young oysters settled on the shell of older oysters.

Oysters are filter feeders that strain their food from the water column; a single adult oyster can filter 50 gallons/day. Overfishing in the 1900's, followed by diseases (Dermo and MSX) starting in the 1950's, has reduced the Crassostrea virginica population by 99%. Before that dramatic decline, the mass of oysters in the Chesapeake Bay had the capacity to filter all the water within the bay in less than a week, and may have consumed up to 75% of the carbon generated by algae in the shallow portions of the Chesapeake Bay by fixing it into shells and biomass of oyster bodies.1

commercial oyster harvests in the Chesapeake Bay show the dramatic population decline in 50 years, due to overharvest and diseases (MSX and Dermo)
commercial oyster harvests in the Chesapeake Bay show the dramatic population decline in 50 years, due to overharvest and diseases (MSX and Dermo)
Source: US Fish and Wildlife Service, Conserving the Chesapeake's Living Resources - Oyster

Individual oysters can adapt to waters disturbed by tides and storms, and oyster beds can adapt to rising sea levels. By one estimate, the water level in the Chesapeake Bay rose 10mm/year as sea level rose and the bay formed after the last Ice Age. Oysters were able to increase the height of their reefs by that amount. The size and extent of oyster reefs in the bay 400 years ago may have been determined by the available food in the water. The oysters were once so plentiful, and so efficient at filtering food, that the species filled its biological niche and there was no opportunity to expand further.2

The word "Chesapeake" may not be Algonquian for "great shellfish bay" despite years of traditional references to the meaning of that name, but idea behind that translation is appropriate. The Chesapeake Bay was "full" with oysters 400 years ago.

Native Americans feasted from oyster bars in the Chesapeake Bay, in the saltwater portions of Tidewater rivers, and on the Atlantic Ocean edge of the Eastern Shore. Centuries of oyster collection are documented by great mounds ("middens") of leftover shells near Native American towns.3

oyster with hard shell of calcium
oyster with hard shell of calcium
Source: US Geological Survey Nonindigenous Aquatic Species Database, Crassostrea virginica

Oyster collecting relied upon simple technology - a stick, antler, or rock to break oysters free. The harvest was extensive, but not intensive. Oyster bars were not destroyed when Native Americans plucked oysters from the top. The "fishery" was sustainable, and oyster bars were common in shallow areas where water salinity was suitable. When John Smith sailed/rowed around the bay and its tributaries in 1608, his men struggled to get their shallop across shallow reefs of oysters exposed at low water; oyster bars were a navigation hazard.

Early English settlers were also able to harvest oysters in great quantities without reducing the ability of the species to recover. In 1686, Durand de Dauphine noted that his host had no difficulty obtaining several hundred pounds of oysters on short notice:4

"He had only to send one of his servants in one of the small boats & two hours after ebb-tide he brought it back full. These boats, made of a single tree hollowed in the middle, can hold as many as fourteen people & twenty-five hundredweight of merchandise."

Since 1900, and especially since the 1950's, oysters have fallen upon hard times in Virginia due to overharvesting, pollution, and disease. Those ancient reefs have been flattened and excavated by tonguing with double-sided rakes to dig oysters by hand, or by dredging to strip mine the oysters from a reef using wind- or motor-powered boats to drag a cage with a hard edge that rips oysters free. New technology allowed watermen to remove oysters faster than they could naturally reproduce, while culture and law permitted extraction without consideration of the natural restocking rate.

oyster midden, now exposed and eroding
oyster midden, now exposed and eroding
Source: National Oceanic and Atmospheric Administration (NOAA), Cultural Resources - Shell Middens

harvesting oysters using rakes oyster beds in deeper water required boats and long-handled tongs
oysters in shallow water could be harvested using rakes, but oyster beds in deeper water required boats and long-handled tongs
Source: Library of Congress, Oystering on the Chesapeake and Fred, a young oyster fisher; working on an oyster boat in Mobile Bay

As the oyster shells were mined (ground up and used as grit in chicken feed, for fertilizer, or for road construction), the reefs disappeared. At Wreck Shoal in the James River, 4-6 feet of oysters have been removed. As reported by the Virginia Institute of Marine Science:5

"Oysters have in the course of their long evolutionary period evolved as reef animals... Prior to 1880 good oyster rocks (bottoms) were common in the York River. They were the results of generation after generation of oyster shells settling on top of the previous crop, until finally the "oyster bars" were exposed at low tide. Those the results of natural conditions, but not for long."

"By 1900 the oystermen had tonged up most of the oysters and had failed to return any appreciable amount of the shells. They sold the shells as well as the meats. The shells were ground and sold as chicken grit or burned into lime."

"No better proof of this lowering or even total removal of the oyster rocks can be presented than the examination and comparison of a York River Coast and Geodetic Chart of 1858 with a recent one. 'Bare at low water' is the notation on the 1858 chart at Pages Rock Lighthouse. Today the reading at the same spot shows a depth of three feet and the bottom is soft mud."

Pages Rock Lighthouse, near modern-day Cheatham Annex of Yorktown Naval Station, as depicted on 1906 map
Pages Rock Lighthouse, near modern-day Cheatham Annex of Yorktown Naval Station, as depicted on 1906 map
Source: US Geological Survey, Williamsburg 15x15 topo map (1906)

A 1999 report, also from the Virginia Institute of Marine Science, summarized the resulting impacts:6

Overfishing in the late 1800s and early 1900s reduced Chesapeake Bay market oyster landings from a peak of about 24 million bushels in 1887 to a more-or-less steady state of about 5 million bushels by 1930. This high harvest pressure also mined the oyster reefs themselves, greatly reducing the reef habitat in the Bay. In the last four decades two protozoan diseases (MSX disease caused by Haplosporidium nelsoni and Dermo disease caused by Perkinsus marinus) have combined to further reduce oyster populations throughout Chesapeake Bay to about 1% of historical levels.

The biological impact of the destruction of the oyster population is significant:7

Oysters are filter feeders, which means that they remove nutrients from the water as they siphon it through their gill system. This filtering process removes the phytoplankton and other small organisms that grow in the water. In essence, each oyster is a small, water-treatment plant that cleans the water passing through it as it feeds. The cumulative effect of millions and millions of oysters feeding each day was to keep the waters of the Chesapeake clear and pristine. Biologists have estimated that when the English settlers reached Virginia and Maryland in the 1600s, oysters were filtering the entire Chesapeake Bay once a week. The result was waters of remarkable clarity, even down to depths of twenty feet or more.

Literally billions of oysters were harvested from the Chesapeake during a single century, and most of these were removed in a forty--year period- with enormous environmental repercussions. In particular, the water-filtering capacity of the Chesapeake was seriously compromised. Whereas in 1600 the water of the bay was completely filtered about once a week, a process that removed the accumulated organic materials suspended in the water, by the late 1900s the remaining oysters would require over one year to accomplish this same feat.

Removal of so many shellfish meant that nutrient levels would build up in the waters. This enrichment was increased even more by human activities in the twentieth century with the dumping of massive quantities of chemicals, fertilizers and other materials into the Bay waters. The result was greater biological production of tiny phytoplankton and other organisms and not enough oysters to eat them. As these creatures died and decayed, oxygen was removed from the water in greater amounts, eventually leading to the development of dead zones.

Evidence suggests that in the early 1900s, the Chesapeake ecology began to shift from being a body of water dominated by bottom dwelling organisms in clear water to one dominated by microscopic animals, plants, and bacteria suspended in murky water.

oyster shuckers removed the meat from the shell, and shells piled up at packing plants oyster shells removed from the Chesapeake Bay were often used for construction, rather than recycled to support another generation
oyster shells removed from the Chesapeake Bay were often used for construction, rather than recycled to support another generation
Source: Library of Congress, A Virginian oyster shucker (c.1896) and Oyster pile, Hampton, Va.

Overharvest of Chesapeake Bay oysters is a classic example of the "tragedy of the commons." Virginia and Maryland did not treat reefs as a renewable resource. The state governments allowed watermen to mine the oyster populations in the same way that coal is mined today: scrape up the resource and haul it away.

Oysters grew on the river and bay bottoms, on submerged land owned by the state rather than by any single individual. There was no incentive for a waterman to leave behind any oysters when harvesting a reef - some other waterman would simply take the oyster, before it had a chance to reproduce.

States did not ensure enough young oysters would remain to repopulate reefs and support perpetual oyster removal. When regulations were passed to manage the harvest, state agencies failed to enforce those regulations consistently. Various ineffective efforts to manage the oyster harvest included limits on dredging, reduced seasons, and prohibition of "foreign" boats.

illegal oyster harvesting including dredging at night
illegal oyster harvesting including dredging at night
Source: Harper's Weekly, The Oyster War in Chesapeake Bay (March 1, 1884)

Foreign boats included Connecticut watermen who moved into the Chesapeake after overharvesting the beds in Long Island Sound - and also boats from across the state line. "Oyster wars" broke out between Maryland and Virginia, as each state tried to block watermen from dredging oysters on the "wrong side" of the state boundary. The Virginia-Maryland boundary arbitration in 1877, determined by the Black and Jenkins decision, was triggered by a desire to define control of oyster beds in Tangier and Pocomoke Sounds.

the Virginia-Maryland boundary was clarified in 1877 to resolve conflict over territory valued for oyster harvesting
the Virginia-Maryland boundary was clarified in 1877 to resolve conflict over territory valued for oyster harvesting
Source: Report of the commissioner on the part of Maryland, for the re-locating and re-marking of the boundary line between Maryland and Virginia in Tangier and Pocomoke Sounds (1877)

Despite clarified boundaries, both local and out-of-state watermen continued to violate Virginia's laws on oyster harvesting. In 1882 and in 1883, Virginia Governor William Cameron led nautical expeditions from Norfolk to capture illegal dredgers in the Rappahannock River. In 1884, Virginia created a naval police force to ensure compliance with oyster regulations. The "oyster navies" of Virginia and Maryland fought with watermen and each other at times until the 1950's, until the oyster population had collapsed and the natural resource no longer justified the effort to control the harvest.8

In the 1890's, Virginia took action to address the loss of natural oyster reefs. Virginia's solution was to increase the supply of oysters, rather than deal with the demand of watermen to harvest an excessive amount. Political influence by the watermen (and the state's reluctance to fund a police force to ensure regulations were followed) blocked effective controls on hunting/gathering wild oysters.

Virginia's supply side strategy was to encourage private farming of oysters. Virginia initiated a privatization process to lease submerged lands, authorizing individuals and companies to create new oyster reefs. Private funding was mobilized to re-establish oyster populations in selected locations, by creating leaseholders of "private rocks."

Physically, new reefs were created by transporting old oyster shells from packing houses (or by mining even older ancient Native American middens) and depositing the shells on the leased portion of submerged land. Seed oysters were moved from beds on the James River to areas within the boundaries of leases.

Hauling shell was the easy part. The politically-challenging part was establishing a legal framework, so naturally-reproducing oyster beds remained open to public harvest but only the individual/company responsible for creating a private reef was allowed to remove oysters from that location.

watermen harvested oysters with 14-foot and 20-foot long tongs, and even in good weather it was hard labor
watermen harvested oysters with 14-foot and 20-foot long tongs, and even in good weather it was hard labor
Source: Library of Congress, Favorite bed for small boats - Gathering and dressing oysters under difficulties

Virginia's privatization program began with identification of the remaining underwater sites where natural oyster production was sufficient to maintain interest in commercial harvest. These areas were mapped during 1892-94 by James Baylor, from the US Coast and Geodetic Survey.

Under the 1892 legislation passed by the General Assembly, local officials maximized the area defined as barren and thus left open to raking/tonguing/dredging by the public. The boundaries of the Baylor Surveys were drawn as straight lines to simplify the initial cost and administration of the surveys. As a result, polygons that included the full extent of where oysters were growing also included substantial buffers of submerged land where no oysters were reproducing naturally.

About 200,000 acres of the submerged bottom were designated as public oyster grounds, while 400,000 acres were made available for private leases. Baylor himself was a political progressive who thought private leases would encourage scientific management of oysters like a crop, replacing the hunting/gathering model where watermen exhausted the natural beds.

However, the business leaders with enough capital to lease submerged lands in Virginia did not raise strong objections to local efforts to draw broad boundaries for public oystering grounds in the Baylor Surveys. (In 1909, James Moore's resurvey of Baylor Survey tracts on the James River determined that 58% of the bottomland was devoid of oysters.)

Allowing excessive acreage minimized political conflict over excluding local watermen from traditional areas, and those planning to plant new beds on leased bottom did not desire areas where oysters were growing naturally. Barren bottomland allowed newly-planted oysters to grow to a larger, more-valuable size without competition from existing oysters.9

Boundaries of underwater beds were hard to mark, and easy to ignore. Once a portion of submerged land was included in a private lease, Virginia law permitted leaseholders to build watchtowers with armed guards to protect their crop from oyster rustlers. State law enforcement to protect private oyster beds was theoretically possible. However, direct action to deal with trespass (or alternatively, tipsters reporting violations to state officials) was more reliable a century ago... and is not uncommon today.

Oyster packing companies with political influence, and a desire to lease submerged lands, supported privatization. Virginia watermen willing to allow privatization in part because the private beds would be harvested by local tong ers, who by law had to be Virginia residents, rather than by dredgers from other states. Also, under the 1902 Constitution of Virginia, the voting power of the watermen themselves was suppressed after the poll tax and other tools restricted the ability of low-income residents to vote.10

in the Warwick River, a small polygon (with purple boundary) of public rocks defined by the Baylor Survey is surrounded by private leases of submerged land (blue polygons)
in the Warwick River, a small polygon (with purple boundary) of public rocks defined by the Baylor Survey is surrounded by private leases of submerged land (blue polygons)
Source: Virginia Marine Resources Commission, The Wreck Shoals-James River Oyster Sanctuary Map

In contrast, Maryland watermen did not support privatization, and the state did not lease significant portions of its submerged lands until the 21st Century. In the 1900's, watermen ensured oyster reefs in Maryland's portion of the Chesapeake Bay, and in bays on the Atlantic Ocean shoreline, would stay public and open to commercial harvest. The downside is that state funding would be required to create new oyster beds in Maryland, since there was no incentive for private funding.

Public access to the areas where oysters were naturally reproducing, as documented in the Baylor Surveys, was incorporated into the 1902 Constitution of Virginia as Article XIII, Section 175. That policy survives in today's state constitution as Article XI, Section 3:11

Natural oyster beds
The natural oyster beds, rocks, and shoals in the waters of the Commonwealth shall not be leased, rented, or sold but shall be held in trust for the benefit of the people of the Commonwealth, subject to such regulations and restriction as the General Assembly may prescribe, but the General Assembly may, from time to time, define and determine such natural beds, rocks, or shoals by surveys or otherwise.

After the Baylor Survey delineated the public oyster grounds where reproduction was occurring naturally, counties appointed oyster inspectors and surveyors to lease submerged lands for private oyster plantings, and to ensure compliance. That responsibility was shifted to the State Fisheries Commission in 1920.

Based on the Compact of 1785, Virginia had equal rights to the river. The conflict between Maryland and Virginia over oyster management continued after World War II. In the 1950's, oyster dredgers from Virginia were famed for operating a "mosquito fleet" that illegally dredged oyster bars on Maryland's submerged land. Maryland threatened to break the Compact of 1785 and assert control over the river's aquatic resources, and Virginia threatened to bring suit in the Supreme Court. The two states then negotiated the Compact of 1958, and created the Potomac River Fisheries Commission (based in Colonial Beach).

Opposition to the compact was strong in Tidewater Maryland, where watermen feared the new arrangement would lead to restrictions on public oyster bars and more leasing. From the perspective of many Maryland watermen, Virginia packing plants relied upon leased beds to provide most of their oysters, and Virginia officials did little to enforce restrictions on the public oyster bars (Baylor grounds).

One opponent tried to modify the Compact of 1958 to regulate recreational and commercial use of aquatic resources in the Chesapeake Bay, as well as the Tidewater portion of the Potomac River between the DC boundary and Point Lookout/Smith Point. Supporters of the compact may have increased publicity of the 1950's "oyster wars," to create support for the bi-state agreement. Opponents were able to force a statewide vote in Maryland, but voters approved the Compact of 1958, replacing the Compact of 1785.12

The Potomac River Fisheries Commission issues licenses for oystering, clamming, and fishing in the Potomac River downstream of DC, and Virginians get equal access to the resource according to the 1958 compact:13

Recognizing that the right of fishing in the territory over which the Commission shall have jurisdiction is and shall be common to and equally enjoyed by the citizens of Virginia and Maryland, the Commission shall make no distinction between the citizens of Virginia or Maryland in any rule, regulation or the granting of any licenses, privileges, or rights under this Compact.

the Potomac River Fisheries Commission has authority in the tidal Potomac River, downstream from the District of Columbia
the Potomac River Fisheries Commission has authority in the tidal Potomac River, downstream from the District of Columbia
Source: ESRI, ArcGIS Online

Virginia Marine Resources Commission (VMRC), which was created in 1968 to replace the State Fisheries Commission, issues leases for use of submerged land not included within the Baylor Surveys, ensures compliance with aquaculture regulations, and enforces state regulations on Virginia's waters and submerged lands.

VRMC also deals with modern-day poaching from leased beds, and illegal harvesting from sanctuaries and closed areas. The General Assembly authorized stronger penalties in 2013, after recovery of the oyster population from its lowest point in 1999 led to a boom in private leasing. Quick raids to scrape oysters from restricted areas on a foggy day can generate quick profits, and failure of some oyster restoration projects might be associated with poaching. The VRMC approach to manage the oyster resource includes law enforcement:14

We're using the tools we have: short seasons, time limits, bushel limits, cull sizes, gear limits... so we just have to keep the guys following the rules.

Since oysters feed by filtering water, there have been claims that restoration of the oyster population will help restore the water quality of the Chesapeake Bay. Oysters extract nitrogen from the bay's water and fix it into their shells and flesh, so each oyster could be viewed as a tiny wastewater treatment plant. Oysters might serve to correct the overload of nitrogen in the bay, if source reduction of urban/agricultural runoff is not fully implemented as proposed in the Total Maximum Daily Load (TMDL) plan developed by the Environmental Protection Agency.

Though each oyster may do its tiny bit for water improvement, processing 50 gallons a day, even a fully-restored population of oysters would not have a significant impact on nitrogen levels in the bay. The oyster harvest from the late 1800's-1920's reached 4 million-7 million bushels/year, and exceeded 1 million bushels/year until 1980-81 before dropping to a low of 18,000 bushels in 1995-96. If restoration is successful and harvest increased to 1 million bushels/year again, that would remove only 0.2 percent of todayís nitrogen load.15

Oysters and Salt

Oyster Restoration in Virginia

Oyster Aquaculture in Virginia

Chesapeake Bay

Virginia and Submerged Lands


oysters grow along the Atlantic Ocean, Gulf of Mexico, and Pacific Ocean
oysters grow along the Atlantic Ocean, Gulf of Mexico, and Pacific Ocean
Source: National Oceanic and Atmospheric Administration (NOAA), Oyster Reefs

characterization of submerged riverbottom at mouth of Rappahannock River; oysters need a hard surface to set
characterization of submerged riverbottom at mouth of Rappahannock River; oysters need a hard surface to "set"
Source: National Oceanic and Atmospheric Administration (NOAA), Lower Rappahannock River, VA, Benthic Habitat Characterization


1. Victor S. Kennedy, "Eastern Oyster," in Habitat Requirements for Chesapeake Bay Living Resources, Maryland Department of Natural Resources, 1991, p.3-1, http://www.dnr.state.md.us/irc/docs/00000260_03.pdf; Crassostrea virginica, Smithsonian Marine Station at Fort Pierce, http://www.sms.si.edu/irlspec/Crassostrea_virginica.htm; Virginia Oyster Gardening Guide, Virginia Coastal Zone Management (CZM) Program, 2013, p.2, http://www.deq.virginia.gov/Programs/CoastalZoneManagement/CZMIssuesInitiatives/Oysters/Gardening.aspx (last checked March 20, 2014)
2. Roger Mann, Juliana M. Harding, Melissa J. Southworth, "Reconstructing pre-colonial oyster demographics in the Chesapeake Bay, USA," Estuarine, Coastal and Shelf Science Volume 85, Issue 2, 10 November 2009, p.221, http://www.sciencedirect.com/science/article/pii/S0370269303016769 (last checked December 3, 2011)
3. "A Dead Indian Language Is Brought Back to Life: Relic of Va. Past Re-Created for Film," Washington Post, December 12, 2006, http://www.washingtonpost.com/wp-dyn/content/article/2006/12/11/AR2006121101474.html (last checked December 3, 2011)
4. Durand de Dauphine, A Huguenot Exile in Virginia, or Voyages of a Frenchman exiled for his Religion with a description of Virginia and Maryland, Gilbert Chinard (editor), The Press of the Pioneers, New York, 1934, p.124
5. William J. Hargis, Jr. and Dexter S. Haven, "Chesapeake Oyster Reefs, Their Importance, Destruction and Guidelines for Restoring Them," Chapter 23 in Oyster Reef Habitat Restoration: A synopsis and Synthesis of Approaches, Edited by M. W. Luckenbach, R. Mann and J. A. Wesson, 1999, Virginia Institute of Marine Science Press , Gloucester Point, VA, p.333 http://web.vims.edu/mollusc/pdffiles/HargisHaven.PDF (last checked December 3, 2011)
6. "Chesapeake Bay Oyster Restoration - Consensus of a Meeting of Scientific Experts," Virginia Institute of Marine Science Wachapreague, Virginia, June 1999, p.4, http://web.vims.edu/vimsnews/CBOysRestor.pdf (last checked December 3, 2011)
7. "Oyster History," Oyster Company of Virginia, http://oysterva.com/oyster-history.html (last checked December 3, 2011)
8. James Tice Moore, "Gunfire on the Chesapeake: Governor Cameron and the Oyster Pirates, 1882-1885," The Virginia Magazine of History and Biography, Vol. 90, No. 3 (Jul., 1982), pp. 374, http://www.jstor.org/stable/4248570 (last checked December 3, 2011)
9. Samuel Paris Hanes, The High Modernist Moment: Oysters, Knowledge Production, and Conservation in the Progressive Era, 1878-1917, ProQuest, 2008, p.254-265, http://books.google.com/books?id=HUZ6MqZzbqEC (last checked March 18, 2014)
10. Christine Keiner, The Oyster Question: Scientists, Watermen, and the Maryland Chesapeake Bay Since 1880, University of Georgia Press, 2010, pp.94-96, http://books.google.com/books?id=xILv5C1D2PsC (last checked March 17, 2014)
11. 1902 Constitution of Virginia, http://confinder.richmond.edu/admin/docs/Virginia_1902.pdf (last checked December 3, 2011)
12. "It's Our River: Commonwealth of Virginia v. Maryland, Take 1," The SlackWater Center, St. Mary's College of Maryland, http://www.smcm.edu/slackwater/onlineExhibits/JFrankRaley/ItsOurRiver.html (last checked April 2, 2014)
13. "Maryland and Virginia Potomac River Compact of 1958," Potomac River Fisheries Commission, http://prfc.us/commission/commission.html (last checked April 2, 2014)
14. "Oyster poaching in VA a cat & mouse game with serious consequences," Bay Journal, March 14, 2014, http://www.bayjournal.com/article/oyster_poaching_in_va_a_cat_mouse_game_with_serious_consequences; "Historical Highlights Of The Virginia Marine Resources Commission," Virginia Marine Resources Commission, http://mrc.virginia.gov/vmrchist.shtm (last checked March 18, 2014)
15. "Oysters are for eating not treating water quality," Bay Journal, July 1, 2014, http://www.bayjournal.com/article/oysters_are_for_eating_not_treating_water_quality; William J. Hargis Jr., Dexter S. Haven, "The Imperilled Oyster Industry Of Virginia: A Critical Analysis With Recommendations for Restoration," Virgina Institute of Marine Science, Special Report No. 290 in Applied Marine Science and Ocean Engineering, February 1988, p.7, http://www.vims.edu/GreyLit/VIMS/sramsoe290.pdf; "Virginia's Oyster Harvests Boom," news release issued by Governor Bob McDonnell, February 7, 2012, archived at https://wayback.archive-it.org/1655/20130404133814/http://www.commerce.virginia.gov/News/viewRelease.cfm?id=1124 (last checked July 7, 2014)

after the Civil War, Virginia's primary customers for oysters were in northern cities
after the Civil War, Virginia's primary customers for oysters were in northern cities
Source: Library of Congress, Just received a supply of those celebrated oysters...

Habitats and Species of Virginia
Virginia and Submerged Lands
Virginia Places