Oyster farming

Harvesting oysters by hand on Willapa Bay, Washington, USA in October 1969

Oyster farming is an aquaculture (or mariculture) practice in which oysters are raised for human consumption. Oyster farming most likely developed in tandem with pearl farming, a similar practice in which oysters are farmed for the purpose of developing pearls. It has been practiced in one form or another since the Ancient Romans cultured oysters in Great Britain and transported them to Italy. The French oyster industry has relied on aquacultured oysters since the late 18th century.

Commonly farmed food oysters include the Eastern oyster Crassostrea virginica , the Pacific oyster Crassostrea gigas, Belon oyster Ostrea edulis, the Sydney rock oyster Saccostrea glomerata, and the Southern mud oyster Ostrea angasi. Oysters naturally grow in estuarine bodies of brackish water. When farmed the temperature and salinity of the water are controlled (or at least monitored) so as to induce spawning and fertilization, as well as to speed the rate of maturation – which can take several years.

Two methods of cultivation are commonly used. In both cases oysters are cultivated to the size of "spat," the point at which they attach themselves to a substrate. The substrate is known as a "culch" or "cultch". The loose spat may be allowed to mature further to form "seed" oysters with small shells. In either case (spat or seed stage) they are then set out to mature. The maturation technique is where the cultivation method choice is made.

In one method the spat or seed oysters are distributed over existing oyster beds and left to mature naturally. Such oysters will then be collected using the methods for fishing wild oysters, such as dredging.

In the alternate method the spat or seed may be put in racks, bags, or cages which are held above the bottom. Oysters cultivated in this manner may be harvested by lifting the bags or rack to the surface and removing mature oysters, or simply retrieving the larger oysters when the enclosure is exposed at low tide. The latter method may avoid losses to some predators but is more expensive.

Oyster predators include starfish, oyster drill snails, stingrays, birds such as oystercatchers and gulls, as well as humans. Diseases that can affect farmed oysters include Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX). In the north Atlantic Ocean oyster crabs may live in an endosymbiotic commensal relationship within a host oyster. Since oyster crabs are considered a food delicacy they may not be removed from young farmed oysters, as they can themselves be harvested for sale.

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  Oyster harvesting using rakes (top) and sail driven dredges (bottom). From L'Encyclpédie of 1771
• 
  Oyster culture using tiles as culch. Taken from The Illustrated London News 1881
• 
  Department of Gironde (33) - Andernos-les-Bains, little boats of the oyster culturists (circa 1920)

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  Working on oysters at Belon, Bretagne, France 2005-10-07
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  Harvesting oysters from the pier at Cancale, Bretagne, France 2005-10-04

See also

• Gathering seafood by hand
• Oyster pirate
• Tongs

Nineteenth century shallow draft sailboats designed primarily for oystering include:

• Bugeye (boat)
• Log canoe
• Sharpie (boat)
• Skipjack (boat)

Further reading

• Kurlansky, Mark. The Big Oyster: History on the Half Shell. New York. ISBN 0-345-47638-7. {{cite book}}: Text "Random House" ignored (help)

External links

• Taylor Shellfish Farms, Shelton, WA
• Marinetics, Inc. - "The Choptank Oyster Company", Cambridge, MD
• Fishers Island Oysters, Fishers Island, NY
• Oregon Oyster Farms, Inc., Newport, OR
• Longline Environment Ltd., Oyster Farm Consultancy, United Kingdom