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Oysters

Oysters. Addison Macaluso. 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

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Oysters

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  1. Oysters Addison Macaluso

  2. Oyster Taxonomy • Phylum Mollusca • Class Bivalvia • Family Ostreidae (True oysters) • Not to be confused with Pterioida • Commonly farmed species: • Eastern oyster • Crassostreavirginica • Pacific oyster • Crassostreagigas • Belon oyster • Ostreaedulis • Sydney rock oyster • Saccostreaglomerata • Southern mud oyster • Ostreaangasi

  3. Eastern Oyster: Crassostreavirginica • Native to the east coast of USA and Gulf of Mexico

  4. Pacific Oyster:Crassostreagigas • Native to Pacific coast of Asia • Most widely grown bivalve worldwide

  5. Belon Oyster:Ostreaedulis • Native to Western and Southern coasts of Europe

  6. Sydney Rock Oyster:Saccostreaglomerata • Native to Australia and New Zealand

  7. Southern Mud Oyster:Ostreaangasi • Native to Australia

  8. 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

  9. Oyster Economy • Market • Production is on the rise • 156,000 tons in 1950 • 4.4 million tonnesby 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

  10. Life Cycle and Larval Stages

  11. Pediveliger Veliger Oyster Spats

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

  13. 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

  14. 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 ¼ 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

  15. 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

  16. 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 10°C • Feed • Plankton and algae • Cultured or wild algae for larvae • Free resource if attached pediveliger grown in ocean

  17. Water Chemistry • Water temperature • ~10°C for active feeding • ~30°C 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

  18. 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 • Vibriovulnificus • Diarrhea and stomach issues in humans • Perkinsusmarinusand Haplosporidiumnelsoni • Massive mortalities in oyster populations

  19. 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

  20. QUESTIONS?

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