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Pearl divers in the Tuamotu
Archipelago had truly exceptional skill, frequently reaching depths of
100-130 feet (30.5-39.6 meters), remaining under water for a long as three
minutes. Unlike divers in India and Ceylon, Tuamotu divers did not use
stones to weigh themselves down. Instead, they prepared for a dive by
hyperventilating, sometimes accompanied by singing. Once in the water,
they used only the strength of their arms to pull themselves down.
Systematic diving among the oyster beds really
began in earnest during the 19th Century. Before the Europeans arrived,
mother-of-pearl oysters, much prized by Tahitian royalty as decorations
for ceremonial clothing, were essentially used, like other shells, in
making fishing tools. There was a steady decline of traditional pearl and
mother-of-pearl production from the 1960s onward, after having been very
intense at the beginning of the 20th Century.
Concentrated within the Tuamotu Archipelago, this
activity decreased as the oyster beds increasingly dwindled. Production
dropped from 645 tons in 1960 to 185 tons in 1970.
The Pearl Farm The pearl farm is spread across the Atoll.
The grafters' laboratories are built on piles and placed around the edge
of the coral reef.
Nearby, rows of buoys show where the spats are
while, further out into the lagoon, black buoys indicate the location of
the pearl oyster banks.
Daily life on the farm: a difficult, delicate and
repetitive job to see the complex cycle through to completion
The cycle begins with the cultivation of the
spats which will provide the best pearl oysters. They need to be carefully
tendered, sorted and calibrated throughout their period of growth before
being selected for the grafting process. The young oysters are placed in
the salt water tanks in the laboratory where, in complete silence, the
grafters take on this most difficult of surgical operations.
Once the process is over, the oysters are placed
in the special nets, one per pocket, which will allow them to locate the
transplant.
They continue to be nurtured even when they have
been put back in the waters off the lagoon: at regular intervals, divers
bring them into the laboratory to be cleaned and brushed down.
The Pinctada, a unique oyster Pinctada is the scientific name given
to pearl oysters, distinguishing them from edible oysters known as
Ostreidae. This group includes Pinctada fucata martensi, the Akoya pearl
oyster that yields small white pearls in Japan, and the larger South Seas
oysters, Pinctada maxima, the silver- or gold-lipped pearl oyster.
The Tahitian pearl comes from Pinctada margaritifera of the variety
cumingi, the black-lipped pearl oyster.
Other varieties of Pinctada margaritifera are
found throughout the tropical Indo-Pacific as far east as the Persian Gulf
and as far west as the Gulf of California. What distinguishes a
Pinctada margaritifera, variety cumingi?
That is the scientific
name of the largest of the black-lipped Pinctada margaritifera oyster that
produces Tahiti's magnificent cultured pearl. The key word in the name is
cumingi, which is the variety of oyster found only in the lagoons of
Tahiti & Her Islands. The name of this variety comes from the name of
the man who first collected it, Hugh Cuming, a naturalist. This specific
oyster is what gives Tahitian cultured pearls their spectacular wide range
of colors, something the other non-cumingi varieties of Pinctada
margaritifera cannot do anywhere else.
The Oyster's Life
- Fertilization of eggs
Having both male and female sex organs, the pearl oyster is a
hermaphrodite. Depending on its age and surrounding water conditions,
the oyster's sex may change.
- The short reproduction period
There are as many males and females in any given population of pearl
oysters. The reproductive organs are functional for only a short
period each year during the five months from October to February
- 24 days later
After fertilization the eggs undergo a stage of cell division. That is
followed by a real metamorphosis of each egg, which, 24 days later,
becomes a D-shaped larva.
- Maturity rate
Out of a million fertilized eggs, only one in ten will reach maturity.
- Lifespan and size of the Pinctada
margaritifera, variety Cumingi
The black-lipped pearl oyster can live up to 30 years, grow to 30 cm
(12 inches) in diameter and weigh up to 5 kilos (11 pounds). For
oysters, diameter is measured from the edge of the shell behind the
hinge (dorsal margin) to the opposite edge, where the shell opens in
front (ventral margin).
During its most pearl-productive period (about
three to seven years), this oyster reaches a diameter of 15.2 cm to 20.3
cm (6-8 inches).
Grafting (The
Human Touch) There is only one
difference between a spontaneously occurring pearl and a cultured pearl,
and that it is at the very beginning of the process that creates a pearl.
Left to nature, some foreign body must find its way accidentally into the
oyster in such a way that it cannot be dislodged, and the oyster then
isolates the intruder over time in smooth layers of aragonite, or
"mother of pearl".
The cultured pearl begins in the same way as the
pearl in nature, with help from a highly skilled grafter at a pearl farm.
The grafter surgically inserts a spherical nucleus of mussel shell into
the oyster to coax the oyster into creating a pearl. After this
moment, nature takes over and the pearl forms in exactly the same manner.
The oyster builds up successive layers of aragonite and conchiolin to
create a pearl. The color, the surface quality, the luster, these
all depend on the interaction of the oyster and the environment just as it
has for millenia.
Preparing the oysters
The oysters are ready for grafting after three
years of cultivation on the pearl farm. Before the grafting begins, each
oyster is deprived of food for a few days in order to slow down their
metabolism and lessen the risk of the grafting being rejected.
Preparing the nucleus
Next, nuclei measuring 2mm-12mm are cut from the shells of certain
varieties of freshwater mussels and then smoothed so that they are
perfectly spherical. The best nuclei come from a mussel that grows in the
Mississippi River in the U.S.
The grafting process
The young oysters are stored in saltwater storage basins at the grafting
laboratory. In this laboratory, highly trained technicians work in
complete silence carrying out the surgical operations of grafting the
nucleus into each oyster throughout the day.
The delicate process of grafting begins by
cutting small squares of from the mantles of the donor oysters. A piece of
the mantle is then inserted along with the mussel shell nucleus into the
oyster's gonad which has been opened up for this delicate operation. The
oyster is then massaged to speed up the healing process.
After the grafting
As the grafting is finished, the oysters are placed into individual
pockets of a special net suspended in a different part of the lagoon. The
individual pockets allow for the immediate detection of an oyster that has
rejected the graft. The surviving oysters continue to receive constant
attention. The divers bring the oysters to the farm facilities at
regular intervals to be cleaned, brushed down and then taken back to their
resting place in the lagoon. For
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