As a result of disease, pollution and over-harvesting, the
Virginia oyster harvest in the Chesapeake Bay has
declined over many years, from nearly ten million bushels at the turn of
the century to a few tens of thousands in the 1990s.
To improve the oyster population in the Bay, the Virginia Institute of Marine Science (VIMS) has encouraged the use of aquaculture methods to increase the growth rate of native oysters. By placing the animals in a favorable growing environment, maturity can be reached in 18 to 24 months, instead of the 4 to 5 years required in natural bottom growth. Because the parasitic diseases MSX and Dermo usually take two years to kill an oyster, the aquaculture method makes successful harvest more likely.
Aquaculture methods of oyster culture have been in use for about a decade. Some of these original growing operations are now becoming profitable and have expanded into commercial ventures. About ten years ago, VIMS encouraged a group of amateur growers to join the project, a group which has grown to perhaps 2000 participants. These "oyster gardeners" typically start 1000 to 2000 oyster seed per year.
Oyster gardeners have generally four goals:
As disease-resistant oysters are developed by VIMS, oyster gardeners will be encouraged to grow and support a number of animals permanently. The large number of gardening sites will help distribute the resistant oysters over the Bay, where they may spawn and multiply.
THE METHOD
The principle of oyster aquaculture is really very simple: get the baby animals into an environment where they have enough room to feed, are protected from smothering by silt, and fed by flowing water of moderate salinity, and can't be reached by predators.
Oyster gardening starts with seed oysters which are 1/4 to 1/2 inch in length. They are easily handled in a mesh bag. Oyster seed is produced in nurseries where selected brood stock is allowed to spawn under ideal conditions. The microscopic animals "set" by attaching to crushed gravel or broken shell where they begin to grow. The nursery devotes about two months to developing the seeds to the size for gardening. Typically, seeds are distributed to gardeners in September or October. Various types of floating devices have been used successfully. The floats hold animals a few inches below the surface of the water. Baskets generally are made of plastic or metal mesh with openings large enough to let the water and food flow through while small enough to keep the oysters in, and are buoyed up by PVC pipe frames, or in some cases, bottles. The floats must be cleaned occasionally because algae and other creatures also find the environment attractive and clog the openings of the mesh. When the oysters are out of the original growing bags they must be protected from otters, raccoons and other predators. Various materials can be used to fashion a lid to exclude predators.
CURRENT DEVELOPMENTS
VIMS and other labs have been working for several years on cross-breeding specimens of Chesapeake Bay oysters that have shown resistance to MSX and Dermo. The latest generation of these experiments shows a good growth rate. Seeds from the first cross-breeding experiments became available to growers in 1998, with additional strains available in 1999.
Currently several groups of oyster gardeners are working to encourage residents of local coastal waters to expand oyster aquaculture. In addition, Virginia Shellfish Growers Association (VSGA) supports both commerical and noncommercial growers of clams and oysters.
Oyster gardener groups provide newsletters and workshops as well as coordinating the ordering and distribution of seed each year. VSGA maintains a newsletter and is active inmatters related to legislature and aquaculture development.
SHELLFISH HEALTH CONSIDERATIONS
Water that has been found to contain excessive E. coli bacteria levels is condemned by the Division of Shellfish Sanitation, VA Department of Health. Condemnation means that oysters cannot be eaten directly from those waters. Records of the condition of the waters in the Northern Neck and Middle Peninsula are kept at the office in White Stone and those south of the York are at the Norfolk office.
Condemned waters do not hinder the growth and spawning of the oysters, and oysters that have grown in condemned water can be rendered safe by moving them to clean water for fifteen days when the water is above 50º F. Most growers with this problem usually move a supply of mature animals to a friend's dock early enough so that they are available for harvest when desired, but the Virginia Marine Resources Commission is working to establish approved relay systems for gardeners.
In early 1998, Virginia Marine Resources Commission implemented
a permit procedure for oyster gardeners. The permit
allows up to 160 square feet of oyster floats from private docks. There
is no charge for the permit and it is valid for 5 years.
FOR MORE INFORMATION CONTACT:
Tidewater Oyster Gardeners Association
c/o Jackie Partin
8218 Hell Neck Road
Gloucester, VA 23061
(804) 694-4407
hellneck@earthlink.net