Today, watermen harvest both hard clams and oysters from the Commonwealth’s waters, though volumes of clams and oyster are diminished from historic levels. In 2017 the total number of shellfish from Virginia was 53.4 million: 37.5 million Hard Clams and 15.9 million Oysters. In the 1850s, more than 150 million oysters were harvested from the Bay each year; three decades later, this number jumped to 2,000 million. At the turn of the twentieth century, the Bay’s oyster fishery was one of the most important in the United States.
However over-harvesting removed huge volumes of oysters from the Bay and led to the demise of the Bay’s healthy reefs. Over the decades the reefs were scraped away by dredging, oyster beds are now often limited to flat, thin layers of dead shell and live oysters spread over the Bay’s bottom. These damaged habitats offer less surface area for reef-dwelling oysters to inhabit, and can be easily buried by sediment.
Disease also befell the oysters. In 2010 it was estimated that by age three, 80% of the oyster po[ulation in the Virginia portion of the Bay would die due to disease. But in the past few years, research from the Virginia Institute of Marine Science (VIMS) has found that oysters are developing disease resistance, and now VIM is actively breeding greater distance resistance in native oyster strains and working with Virginia’s watermen-farmers to provide additional quantities of shellfish. VIMS created different strains by crossbreeding disease-resistant oysters from Louisiana and the Delaware Bay, then from five Virginia rivers (Rappahannock River, Great Wicomico River, Mobjack Bay, York River, and James River).
Clam and oyster farming, also known as aquaculture, is a booming, multi-million dollar industry in Virginia. Restoration is focused on oyster aquaculture and the Virginia Institute of Marine Science, the Commonwealth and Chesapeake Bay Foundation are encouraging oyster farming and gardening. Oyster gardening under private piers and along the shoreline of privately owned waterfront property is becoming increasingly popular among environmentally concerned citizens. The Chesapeake Bay Foundation holds training sessions in oyster gardening.
Oysters are the Chesapeake Bay's best natural filters. A single adult oyster can filter up to 50 gallons of water a day. Oysters also provide essential habitat for fish and other Bay creatures. The eastern oyster is one of the most iconic species in the Chesapeake Bay. For more than a century, oysters made up one of the region’s most valuable commercial fisheries, and the oysters which are filter-feeders continues to clean our waters and offer food and habitat to other animals.
However, over-harvesting, disease and habitat loss have led to a severe drop in oyster populations. Scientists are working to manage harvests, establish sanctuaries, overcome the effects of disease and restore reefs with hatchery-raised seed in an effort to bring back the oyster. In 2010, Maryland and Virginia embarked on a tributary-based restoration strategy that will build, seed and monitor reefs in several Maryland and Virginia waterways. This commitment was incorporated into the Chesapeake Bay TMDL restoration plan. By 2015, six Chesapeake Ba tributaries had been selected for oyster restoration: Harris Creek and the Little Choptank and Tred Avon rivers in Maryland, and the Lafayette, Lynnhaven and Piankatank rivers in Virginia.
According to a January 2018 update from Virginia Institute of Marine Science, 445 acres of oyster reefs are considered complete in the Lafayette River. Restoration targets are being developed for the Great Wicomico, York, Lynnhaven and Piankatank rivers. Historically, the only method of oyster “culture” was transplanting wild harvested oyster seed to leased growing grounds. In the 21st century that has changed. There are now two primary methods of hatchery based oyster aquaculture production in Virginia, intensive culture (containerized) and extensive culture (spat-on-shell). Both typically use the selectively breed genetically improved stocks and triploid, or “spawnless” oysters from Virginia Institute of Marine Science. VIMS developed the procedures to maintain adult brood-stock, manage their life cycle by altering temperature and the amount of algae provided as food, and to manage the oysters through their planktonic stage until they settle on a hard surface (becoming "spat") and begin to grow into adult oysters. It takes two years for VIMS to grow oysters before they are sold.
Intensive culture methods use cultchless, or single seed, containerized for predator protection. Containerization varies but generally consists of off-bottom cages, racks and in some cases, floats. Intensive oyster culture requires more labor in gear and product maintenance and is generally considered more expensive. However, the end result is a consistent and high quality product that has the ability to obtain a higher price in the boxed and half shell markets.
Extensive culture is also referred to as remote setting or spat-on-shell. The primary advantage of spat-on-shell cultivation is that it requires less labor and fewer materials than single oyster cultivation. Therefore, this method is a more economically feasible option for producing large quantities of local oysters for use by Virginia’s oyster processors. Oyster eyed larvae purchased from the hatchery (often owned by the watermen farmers) are transported to setting sites, struck on containerized oyster shells and ultimately planted directly on the bottom.
Because spat-on-shell cultivation produces oysters grown in clusters (similar to wild-caught oysters), the primary product is mostly oysters for shucking rather than single oysters for half-shell consumption. The spat-on-shell process has been enhanced since its start in 2008. Improvements in the quality of eyed larvae coming out of the hatcheries and optimized remote setting methods have cut in half the number of eyed larvae required per bushel of shell. In 2017, growers reported planting 34,000 bushels (or 3,400,000) a 31% decrease from 2016, but that is forecast to increase in 2018. The industry’s expansion depends on a consistent production of large quantities of eyed larvae, which can be problematic with poor water quality. The oysters themselves and all the activities to achieve the Chesapeake Bay TMDL goals will help with that.
Over the past century, the watershed has experienced a change in land use, as urban, suburban and agricultural areas have replaced forested lands and then urban and suburban replaced agriculture. This has increased the amount of nutrients and sediment entering our rivers and streams and contributed to the poor water quality that affects the oysters and all aquatic life. Excess nutrients of nitrogen and phosphorus fuel the growth of algae blooms that create low-oxygen “dead zones” that hinder the development of oyster larvae; sediment that washes off of roads and fields can suffocate oysters and other shellfish. Stress related to poor water quality can make oysters more susceptible to disease, and yet oysters filter water and contribute to the health of the Bay
To restore the Chesapeake Bay, Virginia needs to restore the oysters. Homeowners with access to a pier or dock can become oyster gardeners and raise oyster larvae at home, through oyster gardening programs, but the essential work is being coordinated by Shellfish Aquaculture programs at the Virginia Institute of Marine Science.
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