:-Scientists at
FAU's Harbor Branch Oceanographic Institute achieve a major breakthrough
in the culturing of queen conch pearls, which hitherto had defied other
research scientists and pearl culturists.
Research Scientists at the Florida Atlantic
University's Harbor Branch Oceanographic Institute have achieved a
sensational breakthrough by successfully culturing high-quality queen
conch pearls, a feat that had evaded research scientists and pearl
culturists for over 25 years, according to a report published on
November 3, 2009, on the Florida Atlantic University's Harbor Branch
website www.fau.edu
Queen Conches are an
endangered species after continuous exploitation for centuries as a
source of food
The Queen Conch (Strombus gigas), is a
gastropod mollusk, a sea-snail, whose geographic range is the
neo-tropical Atlantic waters of the Caribbean and the Gulf of Mexico.
These sea-snails are found in the waters off Bermuda, Southern Florida,
Southern Mexico, the entire Caribbean region, Venezuela and Brazil. The
queen conch meat is considered a delicacy, and had been consistently
harvested by people living in the region since ancient times. The queen
conch fishery had been a thriving industry in the region until the
1960s, and in the Caribbean the annual wholesale value of its output had
been around US $60 million. Over fishing and poaching to meet the
unprecedented local and international demand for conch meat, and habitat
degradation such as loss of nursery habitats like shallow-water sea
grass
meadows, led to rapid decline in populations of queen conch throughout
its range, that led to restrictions and total ban on fishing in many
countries, including the US State of Florida, Bermuda, Cuba, Colombia,
Venezuela, Mexico, Virgin Islands, Antilles etc. The Queen Conch is now
considered an endangered species and listed in Appendix II of the CITES
(Convention for the International Trade on Endangered Species).
Queen conch- Strombus gigas
Credit: FAU's Harbor Branch Oceanographic Institute
Conch pearls are a by
product of the queen conch fishery
While the queen conch was mainly harvested as a
source of food since ancient times, an important by product of this
industry was the occasional conch pearl that was found in some of the
sea-snails. The frequency of occurrence of these pearls was about 1 in
10,000 snails, out of which only 1 in 100 was of gem quality. Thus, good
quality conch pearls were indeed very rare, with a probability of
occurrence of 1 in 1,000,000. Yet the annual catch of queen conches was
so enormous, that a considerable quantity of these pearls continued to
be produced annually, even after the demand for such pearls decreased
after its initial popularity during the Belle Époque period from 1901 to
1915.
CIBJO definition of
conch pearls
The CIBJO (The World Jewelry Confederation) defines
conch pearls as non-nacreous pearls consisting of calcium carbonate
arranged concentrically in a crossed lamellar micro-architecture. This
structural characteristic usually produces a flame-like surface pattern
and porcellaneous sheen. Such pearls are produced by various gastropods
including the Queen Conch (Strombus gigas), Horse Conch (Pleuroploca
gigantea), and the Emperor Helmet (Cassis madagasgerensis).
Conch pearls are non-nacreous because nacre, the
substance that is responsible for the luster and iridescence of nacreous
pearls are not formed in these pearls. Hence non-nacreous pearls have a
matte-like appearance of porcelain or ceramic, and are described as
porcellaneous. However, in the case of conch pearls, the lack of luster
and iridescence, seem to be compensated by another spectacular
shimmering effect on the surface, known as a "flame structure." This is
an optical effect, a form of chatoyancy caused by the interaction of
light, with microcrystalline fibers of calcite (crystalline calcium
carbonate), arranged in concentric layers in a crossed lamellar pattern.
The shimmering effect of the "flame structure" like a fire burning on
the surface, is so spectacular, that it surpasses the luster and
iridescence of some low grade nacreous pearls.
The popularity of
conch pearls drop after the Belle Époque period, and the pearls become
valueless
The successful production of cultured Akoya pearls in
Japan, in the 1920s, spelt the doom of the natural pearl industries, in
the traditional pearl producing areas of the world, such the Persian
Gulf, the Red Sea and the Gulf of Mannar. The popularity of natural
conch pearls also decreased after this, due to the availability of cheap
alternatives. However, the exploitation of the queen conch sea-snail
continued in the Caribbean and the Gulf of Mexico, on an unprecedented
scale, with the output increasing annually, not for the conch pearls,
but for their delicious meat, for which there was an ever increasing
demand both in the region as well as internationally. Thus, conch pearls
continued to be produced in the region, but there were no takers for
these pearls, due to the drastic drop in demand.
Conch pearls become a
collectors item after they lose their commercial value
Conch pearls were now purchased only by connoisseurs
and collectors, as there was no commercial value for the pearls. One
such collector was Susan Hendrickson, the marine archaeologist,
paleontologist and professional diver, who shot into international fame
in 1990 for her discovery of the most complete fossil skeleton of T.
Rex, in the Black Hills of South Dakota. During her diving expeditions
to the Caribbean, she developed an interest in conch pearls, which were
available abundantly in the region and began a collection, which
eventually became one of the largest collections of conch pearls in the
world.
Recent surge in
popularity of conch pearls
There has been a surge in popularity of conch pearls
in recent times. Among the reasons attributed for the increase in
popularity of conch pearls are, a general increase in demand for natural
pearls in a market dominated by cultured for over eight decades; the
rarity of occurrence of conch pearls; the availability of conch pearls
in a wide array of colors, such as pink, white, yellow, brown and
golden, a salmon-colored orange-pink being the most sought after color;
the presence of the unique flame structure, in the pinkish and whitish
tones of conch pearls that added to their value; the high specific
gravity, hardness and resistance to wear and tear compared to other
pearls. Susan Hendrickson, who had the largest conch pearl collection in
the world also made a significant contribution to the popularity of the
pearls by going into partnership with the renowned Geneva-based jewelry
manufacturer Georges Ruiz, to produce conch pearl jewelry and popularize
their usage.
Previous attempts to
culture conch pearls
Several attempts had been made by pearl culturists
and scientists, from countries in the geographic range of the sea-snail, to culture conch pearls during the last 25
years. However, none of these attempts had been successful, probably due
to the sensitivity of the sea-snail to the traditional pearl seeding
techniques and the difficulty in gaining access to the gonads of the
sea-snail, where pearls are usually cultured, due to the spiral shape of
its shell.
The successful
breakthrough in culturing conch pearls was achieved by scientists, Dr.
Héctor Acosta-Salmón and Dr. Megan Davis of FAU/HBOI
The successful breakthrough in the culturing of conch
pearls came as a result of around two years of research and
experimentation carried out by scientists, Dr. Héctor Acosta-Salmón and
Dr. Megan Davis from Florida Atlantic University's Harbor Branch
Oceanographic Institute. The two scientists who are considered as the
co-inventors of the novel and proprietary seeding techniques to produce
beaded and non-beaded cultured pearls from the queen conch, have
successfully produced more than 200 high-quality cultured conch pearls
applying this technique. The achievement of the two scientists have been
hailed as significant and comparable to Mikimoto's successful
culturing of Akoya pearls in 1916, that revolutionized the international
pearl industry, making pearls available and affordable to the common
man, previously enjoyed only by a privileged few. Like cultured Akoya
pearls, the new discovery gives a unique opportunity for the
introduction of a new and much-sought-after pearl to the industry, that
has the potential of galvanizing the cultured pearl industry.
Drs. Megan Davis and Héctor Acosta-Salmón
Credit: FAU's Harbor Branch Oceanographic Institute
The seeding
techniques used were modification of the seeding techniques used for
producing saltwater and freshwater pearls
Cultured pearls are of two types - beaded (nucleated)
and non-beaded (non-nucleated). Nucleated pearls are produced in
saltwater oysters and non-nucleated pearls are produced in freshwater
mussels. Nucleated pearls are produced by inserting a spherical shell
nucleus, usually obtained from the shell of a freshwater mussel, into
the gonad or mantle tissue of a recipient saltwater oyster, followed by
a piece of mantle tissue obtained from a sacrificial oyster.
Non-nucleated pearls are produced in freshwater mussels by inserting
only a piece of mantle tissue into the mantle or gonad of a recipient
freshwater mussel. In the production of nucleated pearls from saltwater
oysters, usually only a single grafting is possible at a time, but in
the case of non-nucleated pearls produced in freshwater mussels, several
graftings are possible at a time, producing many pearls. According to
Dr. Héctor Acosta-Salmón two different seeding techniques were used in
inducing pearl formation in the queen conch. One was a modification of
the conventional technique used to produce cultured pearls in freshwater
mussels. This was obviously for the production of non-beaded cultured
conch pearls. The second was a modification of the conventional
technique used for the production of pearls in saltwater pearl oysters,
and was undoubtedly for the production of beaded cultured conch pearls.
Apart from this, details of how the two modified techniques were carried
out; how the inaccessible gonads were approached; how the harvest was
taken without killing the snail etc. are not disclosed.
The culturing process
developed by the scientists are efficient and environmentally
sustainable
The seeding techniques developed by the two
scientists were superior to the techniques used in the culturing of
other pearls due to two reasons. 1) The technique ensured a 100%
survival rate of queen conches after seeding, unlike in other techniques
where a certain percentage of the seeded mollusks perished soon after
seeding. 2) After harvesting the first pearl the queen conch can be used
again for culturing a second pearl. Thus the continued survival of the
queen conch during the first and second culturing periods, makes this
process more efficient and environmentally sustainable, especially in
the light of the dwindling populations of wild queen conches in their
natural range due to over fishing, causing the species to be listed as
endangered under CITES.
The natural habitat,
the feeding habit and growth of queen conches
Queen conches attain their maximum growth and size
when they are around 3 to 5 years old. They can reach a maximum length
of about 30 cm (12 inches), attaining a weight of about 2.3 kg (5 lbs).
In their natural habitat, they can have a life span of about 30-40
years. The habitat of queen conches are the shallow sea grass beds,
consisting of turtle grass (Thalassia) and Manatee grass (Cymodocea),
in the warm and shallow waters of the sub-tidal zone, at depths of 1 to
30 meters. However, the main source of food of the adult conches are the
algae associated with the sea grass, such as Cladophora and Polysiphonia.
The veliger larvae survive mainly on plankton floating in the
environment. It is their herbivorous feeding habit, that confines them
to shallow and warm waters, with plenty of sunlight, known as the "photic
zone" that supports the luxuriant growth of sea grass, and algae that
are associated with it.
The size of the
cultured pearls produced depends on the size of the bead and the culture
time
The first step in attempting the culturing of
pearls in queen conches was the farming of sufficient numbers of
queen conches in aquaculture tanks, in the aquaculture facility at FAU/HBOI.
The process begins with eggs laid by adult queen conches raised in
captivity. The eggs hatch to form veliger larvae, which after a short
period settles down and transforms into a young shell, which is about 1 cm in length in 3
months. The young shell grows rapidly and in 12 months attains a length
of 10 cm. The shell continues to grow until it is about 3 to 4 years
old, when the length of the shell is between 20 to 30 cm. The shell then
stops growing and begins to form a broad flared lip, an indication that
the conch has attained maturity and is now ready for reproduction. It is
not known at which stage in its growth the queen conches are seeded to
produce cultured pearls, but in all probability it must be after the
conch had attained maturity. The researches found that the size of the
cultured pearls produced, was controlled by the size of the bead and the
duration of the culture period. They experimented with culture times
varying from 6 months to 2 years, and found that as the culture time
increases, the size of the cultured pearl also increases.
Characteristics of
the cultured conch pearls produced
The cultured conch pearls produced by the Acosta-Salmón
and Megan Davis technique were of the highest quality, and had a
variety of shapes, such as oval or egg-shaped, spherical,
near-spherical, button-shaped and baroque. Most of the pearls had a pink
or rose color, one of the most popular colors in conch pearls. The
pearls also have the spectacular flame structure characteristic of
rose-colored conch pearls, which compensates for the lack of luster,
characteristic of nacreous pearls.
Some cultured pearls produced at harbor branch
The cultured conch
pearls are handed over to the GIA for testing at its laboratories, and
the results of these tests are to be published in a future issue of Gems
& Gemology, published by the GIA
The FAU/HBOI handed over the cultured conch pearls to
the Gemological Institute of America (GIA) for extensive testing at its
state-of-the-art laboratories, using techniques, that included
conventional gemological examination, determination of the chemical
composition, spectroscopy, spectrometry and microscopy. It is said that
the GIA together with the FAU/HBOI are planning to publish the results
of these tests in one of the upcoming issues of the GIA's scientific
journal, "Gems & Gemology." According to Tom Moses, the senior
vice-president of the GIA Laboratory and Research, the culturing of
conch pearls was a significant development for the pearl industry. He
further stated hat scientists at the GIA were very excited at having the
opportunity to closely examine the unique cultured conch pearls in their
laboratory. He said that several of the pearls examined were truly
top-quality gems, and the GIA was now busy trying to work out
identification criteria, to separate queen conch cultured pearls from
their natural counterparts.
Dr Héctor Acosta-Salmón
and Dr. Megan Davis set the twin records for the first conch pearls as
well as the first non-nacreous pearls to be ever cultured
There are many different types of non-nacreous
pearls, produced both from bivalve as well as univalve mollusks. Among
the bivalve non-nacreous pearls are quahog pearls, scallop pearls and
giant clam pearls. Non-nacreous pearls produced by univalve mollusks (Gastropoda)
such as sea-snails, include the queen-conch pearls, horse-conch pearls
and melo-melo pearls. However, none of these non-nacreous pearls have
ever been successfully cultured before. Thus, Dr. Héctor Acosta-Salmón's
and Dr Megan Davis' achievement in successfully culturing conch pearls,
apart from setting the record as the first conch pearls to be ever
cultured, also sts the record for the first non-nacreous pearls to be
ever cultured.
The significance of the research work carried out by
FAU/HBOI
As the queen conch was listed as an endangered
species by CITES after continuous commercial exploitation for its meat,
a ban has been imposed on its fishing by many countries in its natural
geographic range, including the State of Florida, where the research on
the culturing of conch pearls were conducted. Thus the scientists of FAU/HBOI
had to first learn how to spawn and grow queen conches in captivity, so
that they do not violate the ban on the fishing of wild stocks. Dr.
Megan Davis made a significant contribution in this regard, by making
use of her wealth of experience in aquaculture and marine science. Not
only were the scientists of FAU/HBOI able to raise queen conches in
captivity, but they also learnt how to make them spawn in captivity,
thus enabling queen conches to complete their entire life cycle in
captivity. This enabled FAU/HBOI to conform to the ban imposed by CITES,
and conduct their research work entirely on farm raised queen conches.
The other singular achievement of the scientists of
FAU/HBOI was the development of techniques for seeding queen conches,
with their peculiar twisted anatomy, that made access to the gonads
virtually impossible, and was one of the main reasons that led to the
failure of earlier attempts to culture conch pearls. Besides this
another important achievement of the FAU/HBOI scientists was the
development of a technique for harvesting cultured pearls from seeded
conches without killing them, so that they could be used again for a
second seeding. This is also an important development in the light of
the restrictions placed on the fishing of wild stocks.
Whenever the techniques developed by research
scientists of FAU/HBOI are employed on a commercial basis to culture
conch pearls, such efforts have to be based entirely on queen conches
farmed in tanks by aquaculture, at least until the ban on the fishing of
wild stocks are lifted. Thus the technology of farming queen conches by
aquaculture, become as important as the new proprietary seeding
techniques for producing cultured conch pearls, and their non-lethal
harvesting. Both processes should go hand in hand in order to run a
successful commercial venture to culture conch pearls by aquaculture.
Profile of the
Inventors
Dr. Héctor Acosta-Salmón, Ph.D.
Dr Héctor Acosta-Salmón is a research scientist
attached to the FAU/HBOI in Florida, with a wealth of experience on all
aspects of pearl culture of more than 12 years. His research
experience in pearl culture, covers all the commercial species of pearl
oysters such as the Akoya oyster (Pinctada fucata), the Black-lip oyster (Pinctada
margaritifera), the Silver-lip oyster (Pinctada maxima), found in the Western
Pacific, and the Rainbow-lip oyster and the Panamian pearl oyster (Pinctada
imbricata) found in the Eastern Pacific. He did his doctoral studies at
James Cook University in Australia, focusing on pearl oyster brood stock
management and pearl quality. He joined FAU/HBOI in 2006, serving as a
post-doctoral investigator, and applying his knowledge on pearl culture
technology, during his post-doctoral studies and research. During his
tenure with FAU/HBOI he concentrated his research efforts in developing
techniques to culture queen-conch pearls, something that had eluded
scientists for over two decades. In addition to his work as a
post-doctoral investigator, he also served as an assistant research
professor at FAU/HBOI until 2009. He is now associate scientist at
Centro de Investigaciones Biológicas del Noroeste in La Paz, B.C.S.,
Mexico.
Dr Megan Davis Ph.D.
Dr. Megan Davis has longtime experience in
aquaculture and marine science, lasting over 30 years. While working on
a commercial queen conch farm co-founded by her in the Turks and Caicos
Islands, she developed commercial culture of conch from eggs to
juveniles and then adults. She joined FAU/HBOI in 1996, and was later
appointed as director for aquaculture and stock enhancement. In the year
2000, she successfully led an effort for inducing egg laying in
tank-reared conch, thus enabling the entire life cycle of the queen
conch to be completed in captivity in aquaculture. This enabled the
farming of sufficient numbers of queen conches in captivity that
was subsequently used in the research activities aimed at culturing
conch pearls. Her aquaculture skills with queen conch, contributed in no
small measure for the successful culturing of queen conch pearls.
Apart from the queen conch she has also done
extensive research on the aquaculture of spiny lobsters and marine fish.
She has directed her research efforts to develop aquaculture species for
food and stock enhancement, that eases fishing pressure on wild stocks
that are becoming scarce. Her efforts are also geared at producing
aquaculture species and systems, that are cost effective, energy
efficient and environmentally sustainable. She has also been actively
involved in aquaculture retraining and educational outreach programs,
assisting individuals in advancing the aquaculture industry.
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Related :-
1) Queen Mary Conch Pearl Brooch
2)
Susan Hendrickson's Conch Pearls
External Links :-
1)
Scientists at FAU’s Harbor Branch Oceanographic
Institute are the First to Unlock the Mystery of Creating High-quality
Cultured Pearls from the Queen Conch - www.fau.edu/hboi
References :-
1) Scientists at FAU’s Harbor Branch Oceanographic
Institute are the First to Unlock the Mystery of Creating High-quality
Cultured Pearls from the Queen Conch - www.fau.edu/hboi
2) The Palm Beach Post - Harbor Branch researches
find way to culture conch pearls - by Jeff Ostrowsky.
www.palmbeachpost.com
