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Oysters Addison Macaluso

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Oyster Taxonomy Phylum Mollusca Class Bivalvia Family Ostreidae (True oysters) Not to be confused with Pterioida Commonly farmed species: Eastern oyster Crassostrea virginica Pacific oyster Crassostrea gigas Belon oyster Ostrea edulis Sydney rock oyster Saccostrea glomerata Southern mud oyster Ostrea angasi

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Eastern Oyster: Crassostrea virginica Native to the east coast of USA and Gulf of Mexico

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Pacific Oyster: Crassostrea gigas Native to Pacific coast of Asia Most widely grown bivalve worldwide

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Belon Oyster: Ostrea edulis Native to Western and Southern coasts of Europe

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Sydney Rock Oyster: Saccostrea glomerata Native to Australia and New Zealand

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Southern Mud Oyster: Ostrea angasi Native to Australia

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Oyster Economy Human uses for oysters: Food Farming dates back to Roman times Healthy Cultivation is sustainable and environmentally friendly Reef builders Protect coastlines from wave action Shell collecting Oyster gardening

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Oyster Economy Market Production is on the rise 156,000 tons in 1950 4.4 million tonnes by 2003 More than any other species of seafood China: 84% of oyster production globally Japan: 261,000 tonnes Rep. of Korea: 238,000 tonnes France: 115,000 tonnes USA: 43,000 tonnes 2010: Gulf coast region harvested 15.5 million pounds Market price: 60 cents to $1.20 per oyster $2-$3/oyster in restaurant

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Life Cycle and Larval Stages

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Veliger Pediveliger Oyster Spats

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Reproduction in Captivity Use broodstock conditioned for spawning and maturing Spawning induced by stimuli in the environment 86 to 90F Single female up to several million eggs Fertilized eggs Larva 24-48 hours Washed and graded until pediveliger develops 10-14 days Ready for setting

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Production Methods Set the pediveliger On finely ground oyster shell Finely ground shell= Microcultch Forms subsequent single oysters Good for half-shell market Special setting tanks Or on whole shell in mesh bags Form clumps Like those on reefs

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Production Method: Grow-outs Set on microcultch Maintain several weeks in containers Need good flow of seawater or fed cultured algae Put into plastic mesh bags when 1/8 to inch Put on racks or suspended with rope to keep off bottom (predators) Maintained in bags until harvest May need to change bags during growth

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Production Methods: Grow-out Whole shell Can be held in hatchery until spat development Bags held in SW ponds or in ocean on racks Tightly packed in mesh bags Protects from predators Harvested when desirable size is reached

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Feeds and feeding Filter feeders Create current through gills with cilia Plankton in current are trapped and digested About 1.3 gal/hr Most active about 10C Feed Plankton and algae Cultured or wild algae for larvae Free resource if attached pediveliger grown in ocean

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Water Chemistry Water temperature ~10C for active feeding ~30C to stimulate spawning Salinity Tolerable 10 to 25 ppt pH Optimal range: 6.75-8.75 Declining populations outside range Low pH can dissolve CaCO3 shell

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Disadvantages of Oyster Aquaculture Labor intensive Timing is important Transportation between life stages Many predators Starfish, oyster drill snails, stingrays, Florida stone crabs, birds, Adam Richman (15 dozen) Pathogens Vibrio vulnificus Diarrhea and stomach issues in humans Perkinsus marinus and Haplosporidium nelsoni Massive mortalities in oyster populations

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Advantages of Oyster Aquaculture Feed is cheap Algae is easy to cultivate Free if grown in ocean Relatively easy and low tech Good payout Oyster value on the rise Eco friendly Protects coastlines Stabilize sediment Water quality maintenance

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QUESTIONS?