Oyster farming

Oyster farming for pearl collection

1. OYSTER FARMING Submitted to: Dr. Zubair Anjum Presented by : Imran Ullah Registration No # 15-arid-2816

2. Oyster The word  oyster  is used as a common name for a number of different families of saltwater clams, bivalve  molluscs. Many oysters are in the superfamily  Ostreoidea. First attested in English during the 14th century ,  the word "oyster" (L. osteon ), "bone ". Feed on anything 3-12 microns in size by filtering especially phytoplanktons .

3. Habitat and Distribution L ive in marine  or brackish  habitats. Live mostly in the intertidal zone. Live between rocks and attached to hard substrates . No preference to ocean temperature however they feed best at 50 degrees . Mostly found on the sea shores of Europe, North America, South America and Australia continents.

4. Life History Reach sexual maturity at 1 year of age. Protandric - Young oysters are usually male and change to female after first spawning season. Water temperatures above 25oC trigger spawning. Salinity above 10 ppt. Spawn between March and November

5. Oyster farming   A quaculture  (or mariculture) practice in which oysters are raised for human consumption. Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula and later in Britain for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century. Methods of oyster farming Bottom culture system Off bottom culture system Tray culture Cage culture Rack-and-bag culture

6. Bottom  culturing C losest method to growing oysters like wild oysters . Farmed oysters do not set on a surface like wild spat. T hey have the same grow-out pattern as their native cousins since they are filtering the same water and living on the same bottom that affects their shell color and rigidity . The main benefit of bottom culturing is the ability to produce robust and hearty shells.

7. Off-Bottom Methods Tray  culture I n tray culture, oysters are grown in oyster grow-out trays . H ave the same function as oyster grow-out bags. C an be stacked to conserve space.

8. Cage  culture Cages are exactly what they sound like. H ouse oyster grow-out mesh bags and keep them secure from floating away or touching the bottom . Cages require a pretty stable bottom because they are quite heavy and may sink into the mud if the bottom is too soft.    Gives more protection than the open water and more space to grow.  

9. Rack-and-bag culture O ysters are placed into oyster grow-out bags.   Tied to a steel rebar rack . H ighly dependent on the tidal range of an area . Area need low enough tides for growers to access the bags.

10. Economic Importance As food C ontain more zinc than any other food . H eart healthy . H elp you lose weight. G ood source of other essential nutrients . H elp improve your energy . H elp lower your cholesterol.

11. Pearl formation Fewer than 20 species of the 8,000 mollusks produce pearls . Classified by gemologists as cultured stones . They are organic. Made of NACRE a natural substance produced by mollusks that also costs the inside of the animal’s shell (also called “mother of pearl ”). Nacre is made up mostly of calcium carbonate in the form of the mineral aragonite. Held together by crystal layers called conchiolin .

12. Types of pearl Natural Pearls Parasitic Invasion Mollusk forms a sac around the intruder and secretes nacre from the mantle tissue (the layer of tissue that surrounds the body of the mollusk and lines the shell ).

13. Cultured Pearls Human assistance w/bead or tissue nucleation Nacre secreted around bead or mantle tissue Beads for saltwater oysters Tissue for freshwater

14. Pinctada fucata “ Akoya ” Mostly found in Japan and China. White, cream or yellow in colour . Pearls usually 2-11mm in size, majority 6-7 mm Usually spherical preferred

15. Pinctada maxima “South Sea ” Australia, Philippines, Indonesia. Largest size among pearls. Yellow or silver in colour . Often 9-20 mm with the majority about 13 mm

16. Pinctada margaritifera “Tahitian ” French Polynesia (Tahiti ). Black or silver in color. Spherical generally range in size from 8-13 mm. Often black hue but different tones.

17. Nucleating the Oyster 2 types of nucleation. i) Bead (pieces of fresh water muscle used) ii) Tissue (a slice of mantle tissue, plus a nucleation bead) When nucleated: Slow metabolism Careful opening (Tahitian and South Sea can be re-nucleated) Add Tissue and/or bead nucleus Freshwater usually tissue alone (no bead )

18. Farming Cultured Pearls Pearls Farms Small family farms Large commercial/sophisticated operations

19. Problems/Challenges Pollution Severe weather (drought/flooding) Red Tide

20. Harvesting Cultured Pearls Every 2-3 months mollusks cleaned. Harvesting: 8-24 months Akoya . 2 years Tahitian/South Sea. 2-6 years Freshwater.

21. Processing Cultured Pearls Bleaching. Dyes. Sorting. Size, shape, luster, surface quality, matching ability. Drilling. Full (necklaces ). Half (earrings, posts ).

22. Judging Pearl Quality There are 7 features that directly affect a cultured pearl’s beauty and value. Collectively called “VALUE FACTORS ”. Understanding these will give you the product knowledge to help recognize the beauty and rarity of all pearl types. The value factor are i) Size. ii) Shape. iii) Color. iv) Luster. v ) Surface quality. vi ) Nacre quality. vii) Matching.