Transcript Pearl Oysters - Megann Santana

• Genus: Pinctada
• Pearls in fashion (mostly)
• Pinctada margartifera
• Tahitian peals (black)
• Pinctada fucata
• Akoya pearls (classic)
• Pinctada maxima
• South Sea pearls
• Pearls are the only organic gems and require no processing to reveal
their natural beauty.
• 1 in 2,000 pearl oysters contain a natural pearl.
• Natural pearls are formed when the pearl oyster reacts to an irritant
by coating it with nacre, the shiny iridescent material found on the
inner surface of the shell.
• Natural pearls are usually small, of various colors and irregular in
shape.
• The high value of natural pearls led to the creation of pearl fisheries
in nearly every part of the world where pearl-producing mollusks
were found.
• Most of these pearl fisheries were short-lived because the fishers
soon over-exploited the natural stocks.
• Prompted by the high value and scarcity of natural pearls,
Japanese researchers developed methods that brought pearl
production under the control of humans in the early twentieth
century.
• Importance To Cultivators
• Sell meat, shells, and mostly pearls
• Importance to Businesses
• provide oysters to consumers in various ways:
1. restaurant cooks and serves oysters
2. jewelry business fashions oyster pearls into jewelry
3. Stores sell oyster shells to be used with arts and crafts
• Importance To Government
• In terms of oyster meat, the estimate of annual worldwide oyster cultivation is
3.2 million bushels/$20 per bushel.
• The cultivation of pearls is harder to put a price, but approximately 10 tons
produced.
• AN EXCEEDINGLY RARE DOUBLE-STRAND NATURAL
PEARL NECKLACE. $ 3.7 million
• $2.3 million at Sotheby’s in 1992
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Japan (make up 80% of pearl industry)
Australia
Indonesia
Myanmar
China
India
Philippines
Tahiti
• Find a good location
• Collect sperm larvae
• Thermal stimulation induces spawning.
• Larvae are free-floating in the water
• Larvae must be a few weeks old.
• Larvae develop into juveniles, move to a “nursery”
area or juvenile net.
• Wait a few months, transfer juveniles to a bigger net
• Wait >2 years to graft oysters
• Move to a bigger net and wait another 1 ½ year to
harvest pearls
• A/n nucleus/irritant (usually mother of pearl) is inserted with a
piece of donor mantle tissue into the pearl pocket.
• If it is rejected then can create deformed “Keshis”
• “Rejected” meaning no nucleus because the oyster got rid of it, but the
mantle tissue remains and eventually formed a baroque shaped form with
no nucleus inside of it.
• Oysters may be seeded more than once (species specific)
• Raft Culturing
• Mostly used in bays
• Long-line culture method
• Cages are hung from horizontal ropes or chains connected to floats.
• Oysters are threaded at onto a small thread or rope that is hung from a
raft.
• Good for open ocean environments
• On-bottom culture
• Can only be used in areas of granite or coral sand composition of the sea
bottom.
• Pearls are harvested after 2 – 6 years except some
that are ready around 8 months
• Harvesting is done in the winter months
• X-ray’s determine pearl size before harvesting
• Harvested pearls are then cleaned, polished, and
treated
• Food is supplied by filtering water
• In larval and nursery stage, fed with microalgae and algae.
• Little to no labor until grafting and harvesting time
• Temperature
• 20 – 25C
• Salinity
• Prefer higher salinities, but tolerate wide range.
• Bottom
• Gravelly
• Avoid sandy or muddy bottoms, reduce pearl quality.
• Depth
• Optimum depth at ~ 15m
ADVANTAGES
• Almost all new pearls come
from aquaculture
• Almost any size, color,
luminosity, shape, etc.
• Little labor
DISADVANTAGES
• Limited production of more
expensive pearls.
• Expensive to start
• Time consuming (2 years before most
harvesting is ready)
• In competition with imitation
pearls.
• Can be effected by weather or
natural disasters.
• Possibly dangerous harvest
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