Oyster farming
Encyclopedia
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
(or mariculture
Mariculture
Mariculture is a specialized branch of aquaculture involving the cultivation of marine organisms for food and other products in the open ocean, an enclosed section of the ocean, or in tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of marine fish,...
) practice in which oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s 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 was practiced by the ancient Romans
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
as early as the 1st century BC on the Italian peninsula
Italian Peninsula
The Italian Peninsula or Apennine Peninsula is one of the three large peninsulas of Southern Europe , spanning from the Po Valley in the north to the central Mediterranean Sea in the south. The peninsula's shape gives it the nickname Lo Stivale...
and later in Britain
Roman Britain
Roman Britain was the part of the island of Great Britain controlled by the Roman Empire from AD 43 until ca. AD 410.The Romans referred to the imperial province as Britannia, which eventually comprised all of the island of Great Britain south of the fluid frontier with Caledonia...
for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century.
Varieties of farmed oysters
Commonly farmed food oysters include the Eastern oysterEastern oyster
The eastern oyster — also called Atlantic oyster or Virginia oyster — is a species of true oyster native to the eastern seaboard and Gulf of Mexico coast of North America. It is also farmed in Puget Sound, Washington, where it is known as the Totten Inlet Virginica. Eastern oysters are and have...
Crassostrea virginica, the Pacific oyster
Pacific oyster
The Pacific oyster, Japanese oyster or Miyagi oyster , is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand.- Etymology :...
Crassostrea gigas, Belon oyster
Belon oyster
Ostrea edulis is a species of oyster native to Europe and commonly known as the European flat oyster, Colchester native oyster, mud oyster, or edible oyster . When mature O. edulis adults range from across...
Ostrea edulis, the Sydney rock oyster
Sydney rock oyster
The Sydney rock oyster, Saccostrea glomerata, formerly known as Saccostrea commercialis, is an oyster species endemic to Australia and New Zealand...
Saccostrea glomerata, and the Southern mud oyster
Ostrea angasi
The southern mud oyster or native flat oyster, Ostrea angasi, is endemic to southern Australia, ranging from Western Australia to southeast New South Wales and around Tasmania.-Diet:...
Ostrea angasi.
Cultivation
Oysters naturally grow in estuarineEstuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
bodies of brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
. 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.
Three methods of cultivation are commonly used. In each case 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
Scallop dredge
A fishing dredge, also known as a scallop dredge, oyster dredge, etc, is a kind of dredge which is towed along the bottom of the sea by a fishing boat in order to collect a targeted edible bottom-dwelling species. The gear is used to fish for scallops, oysters and other species of clams, crabs, and...
.
In the second method the spat or seed may be put in racks, bags, or cages(or they may be glued in threes to vertical ropes) which are held above the bottom. Oysters cultivated in this manner may be harvested by lifting the bags or racks 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.
In the third method the spat or seed are placed in a culch within an artificial maturation tank. The maturation tank may be fed with water that has been especially prepared for the purpose of accelerating the growth rate of the oysters. In particular the temperature and salinity of the water may be altered somewhat from nearby ocean water. The carbonate minerals
Carbonate minerals
Carbonate minerals are those minerals containing the carbonate ion: CO32-.-Anhydrous carbonates:*Calcite group: Trigonal**Calcite CaCO3**Gaspeite CO3**Magnesite MgCO3**Otavite CdCO3**Rhodochrosite MnCO3**Siderite FeCO3**Smithsonite ZnCO3...
calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
and aragonite
Aragonite
Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
in the water may help oysters develop their shells faster and may also be included in the water processing prior to introduction to the tanks. This latter cultivation technique may be the least susceptible to predators and poaching, but is the most expensive to build and to operate. The Pacific oyster C. gigas is the species most commonly used with this type of farming.
Environmental Impact
The farming of oysters and other shellfish is relatively benign or even restorative environmentally, and holds promise for relieving pressure on land-based protein sources.Predators, diseases and pests
Oyster predators include starfish, oyster drill snailsUrosalpinx cinerea
Urosalpinx cinerea, common name the eastern or Atlantic oyster drill, is a species of small predatory sea snail, a marine gastropod mollusk in the family Muricidae, the murexes or rock snails....
, stingray
Stingray
The stingrays are a group of rays, which are cartilaginous fishes related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes, and consist of eight families: Hexatrygonidae , Plesiobatidae , Urolophidae , Urotrygonidae , Dasyatidae , Potamotrygonidae The...
s, Florida stone crab
Florida stone crab
The Florida stone crab, Menippe mercenaria, is a crab found in the western North Atlantic, from Connecticut to Belize, including Texas, the Gulf of Mexico, Cuba and the Bahamas that is widely caught for food.-Description:...
s, birds, such as oystercatcher
Oystercatcher
The oystercatchers are a group of waders; they form the family Haematopodidae, which has a single genus, Haematopus. They are found on coasts worldwide apart from the polar regions and some tropical regions of Africa and South East Asia...
s and gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s, as well as humans.
Diseases that can affect either farmed C. virginica or C. gigas oysters include Perkinsus marinus
Perkinsus marinus
Perkinsus marinus is a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as "Dermo" ,and is characterized by proteolytic degradation of oyster tissues...
(Dermo) and Haplosporidium nelsoni
Haplosporidium nelsoni
Haplosporidium nelsoni is a pathogen of oysters, that originally caused oyster populations to experience high mortality rates in the 1950s, and still is quite prevalent today. The disease caused by H. nelsoni is also known as MSX...
(MSX). However, C. viginicus are much more susceptible to Dermo or MSX infections than are the C. gigas species of oyster. Pathogens of O. edulis oysters include Marteilia
Marteilia
Marteilia is a genus of Rhizaria. Species include Marteilia sydneyi and Marteilia refringens.Marteilia refringens is a unicellular parasite affecting the digestive system of the flat oyster, Ostrea edulis. Other species that can be infected include the Australian mud oyster , the Argentinean oyster...
refringens and Bonamia ostrea. In the north Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, oyster crab
Oyster crab
The oyster crab, Zaops ostreus, is a small, whitish or translucent crab in the family Pinnotheridae. It is less than half an inch across, and lives inside the gills of an oyster or a clam. It uses the oyster for protection and lives on the food that the oyster gets for itself. It is found in...
s may live in an endosymbiotic
Endosymbiont
An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis...
commensal
Commensalism
In ecology, commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral...
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.
Polydorid polychaetes are known as pests of cultured oysters.
See also
- Gathering seafood by handGathering seafood by handGathering seafood by hand can be as easily as picking shellfish or kelp up off the beach, or doing some digging for clams or crabs, or perhaps diving under the water for abalone or lobsters....
- Oyster pirateOyster piratethumb|300px|Oyster pirates on the Chesapeake Bay in 1884Oyster pirate is a name given to persons who engage in the poaching of oysters. It was a term that became popular on both the west and east coasts of the United States in the nineteenth century....
- Oystering machineryOystering machineryIn oyster hatcheries fewer machines are needed but the most important one is the nursery tank system that keeps the oyster larvae alive.The nursery tank system was developed in Florida....
Nineteenth century shallow draft sailboats designed primarily for oystering include:
- Bugeye
- Log canoeLog canoeThe log canoe is a type of sailboat developed in the Chesapeake Bay region. Based on the dugout, it was the principal traditional fishing boat of the bay until superseded by the bugeye and the skipjack. However, it is most famous as a racing sailboat, and races continue to be held.The history of...
- PungyPungyThe Pungy is a type of schooner developed in and peculiar to the Chesapeake Bay region. The name is believed to derive from the Pungoteague region of Accomack County, Virginia, where the design was developed in the 1840s and 50s....
- SharpieSharpie (boat)Sharpies are long, narrow sailboats with flat bottoms, extremely shallow draft, centerboards and straight, flaring sides. They are believed to have originated in the New Haven, Connecticut region of Long Island Sound, United States...
- Skipjack
Also, from the 1880s on, the powerboat known as the Chesapeake Bay deadrise
Chesapeake Bay deadrise
The Chesapeake Bay deadrise is a type of traditional fishing boat used in the Chesapeake Bay. Watermen use these boats year round for everything from crabbing and oystering to catching fish or eels. Traditionally wooden hulled, the deadrise is characterised by a sharp bow that quickly becomes a...
was a hull type used for oystering in the Chesapeake Bay
Chesapeake Bay
The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...
of the United States.