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
 Live 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
 Aquaculture (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
i. Tray culture
ii. Cage culture
iii. Rack-and-bag culture

6. Bottom culturing
 Closest method to growing oysters like wild oysters.
 Farmed oysters do not set on a surface like wild spat.
 They 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
 In tray culture, oysters are grown in oyster grow-out trays.
 Have the same function as oyster grow-out bags.
 Can be stacked to conserve space.

8. Cage culture
 Cages are exactly what they sound like.
 House 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
 Oysters are placed into oyster grow-out bags.
 Tied to a steel rebar rack.
 Highly dependent on the tidal range of an area.
 Area need low enough tides for growers to access the bags.

10. Economic Importance
As food
 Contain more zinc than any other food.
 Heart healthy.
 Help you lose weight.
 Good source of other essential nutrients.
 Help improve your energy.
 Help 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.