Introduction:
Depending on where it is grown, the American oyster may also be known as
an Atlantic or Eastern oyster. Its Latin name is Crassostrea virginica
and it is native to the North American coast. A hardy species, this
oyster can live in a range of temperatures from -2°C to 32°C. It has a
thick shell with a rough, sculptured appearance and varies in color.
Usually it is a mixture of brown, gray, green and white shades. Most
American oysters take between four and seven years to reach market size,
and there are records of 100 year old oysters found in the waters of the
Bras d'Or Lakes.
Reproduction:
American oysters spawn in summer when the water warms
up to above 20°C. The oysters release eggs and sperm into
the water at intervals over a period of four to six weeks.
Fertilization takes place in the open water and cell division
begins.
Life Cycle:
The fertilized eggs of the oyster first develop into microscopic
larva. Within 24 hours, they form a shell and develop organs
to help them swim and feed. This consists of a disc covered
with vibrating hairs. For the next three weeks, the larva
swims and feeds on microscopic plants in the plankton community.
Soon the oyster reaches the size of a grain of pepper and
it searches for a place to settle. It then attaches itself
and remains there to grow into a mature oyster.
Feeding Habits:
American oysters feed primarily on plankton -- microscopic
plants and animals in the water. When water conditions are
favorable, the oysters feed almost continuously.
Growing Techniques:
Off-bottom culture is commonly used in the Maritimes.
This technique uses rafts, floating longlines and fences.
Cultch (a substance used to attach spat) is strung like
beads on wire or nylon rope. This is then suspended above
the bottom to collect the setting larvae. The collected
spat are grown in suspension until they reach the desired
length. Finally, they are separated from the cultch and
either planted on the bottom or placed on trays that are
suspended in the water. Held in suspension, the oysters
grow quickly and develop plumper meats than those bottom
grown.
Farming Areas:
The Northumberland Strait shore area of Nova Scotia has
traditionally been an excellent place to grow American oysters
and this activity continues today. The Bras d'Or Lakes in
Cape Breton have also been a popular place for farming American
oysters for many years.
Conclusion:
For more information, contact Aquaculture
(aquaculture@gov.ns.ca).
Nova Scotia Fisheries and Aquaculture
P.O. Box 2223
Halifax, Nova Scotia
Canada B3J 3C4
Phone: (902) 424-0356
Fax: (902) 424-4671
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