Chesapeake Bay Oysters
An
oyster float for raising oysters at your dock.
The following information is from the
Tidewater Oyster Gardeners Association.
OYSTER GARDENING IN
VIRGINIA
As a result of disease, pollution and overharvesting, 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 or 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 three years ago, VIMS encouraged a group of amateur
growers to join the project, a group which has grown to more than 200
participants. These "oyster gardeners" typically start about 2000 oyster seed
per year.
Oyster gardeners have generally three goals:
1.
Experiment with the aquaculture method in the hope of improving its
efficiency.
2. Get a lot of oysters in the water to provide filtering of
the Bay.
3. Harvest the crop before the diseases hit it and enjoy an oyster
roast!
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, are 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 mesh bags. 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.
The seeds grow rapidly in fall and spring, and although they
will encounter the diseases that summer, they have two more rapid growing
seasons before the disease is fatal. Thus, the young oysters will reach harvest
size by 12 to 14 months, and can be harvested through the winter and the
following spring.
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 this
cross-breeding may be available in the near future, and will be distributed as
soon as possible to growers.
Currently several groups of oyster
gardeners are working to encourage residents of local coastal waters to expand
oyster aquaculture. In addition, the Virginia Shellfish Growers Association
(VSGA) supports both commercial and non-commercial 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 in matters related to legislation 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 of the Virginia 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 south of the York 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 a period of time when the water is above
50 degrees 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.
PERMITTING PROCESS
In early 1998, Virginia Marine
Resources Commission implemented permit procedures for oyster gardeners. A
permit will allow up to 160 sq. ft. of oyster floats from private docks. There
will be no charge for the permit and it will be valid for 5 years. Contact the
Habitat Management Division at VMRC, 757-247-2200.
For more details, feel
free to call:
Bruce &
Jill Anderson
Telephone: 804-436-5251
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Copyright 2002, Bruce & Jill Anderson