Cultivation of the Conch Pearl: A Comparison to Natural & What the Future Holds
Dr. Héctor Acosta-Salmón & Dr. Megan Davis
The queen conch, Strombus gigas, is a large gastropod found in Florida and throughout the Caribbean, Central America, and Bermuda. It naturally produces valuable pearls in a variety of colors and shapes with a porcelain luster like the interior of the conch shell. Although known and prized for their deep pink color, the pearls also are found in orange, white, yellow, and brown. The conch pearl frequently exhibits a characteristic ‘flame’ structure or pattern that adds value and is caused by fibrous, prismatic crystals perpendicularly aligned to the pearl surface.
Once abundant, the queen conch is considered a commercially threatened species, having been placed on the Convention on International Trade in Endangered Species Appendix II list in 1992. Dwindling populations from overfishing and environmental changes have made natural pearls rarer, leading to a multi-fold increase in value. Producing conch cultured pearls will provide the market with a supplement to the natural conch pearl market.
Although queen conch aquaculture methods are well established, attempts to develop pearl culture techniques for this species were unsuccessful until conventional seeding techniques for pearl oysters and freshwater mussels were modified. Hatchery-produced queen conch were seeded with either one nucleus and mantle tissue (i.e., beaded) or mantle tissue only (i.e., non-beaded). Non-beaded cultured pearls were sampled after six weeks, 12 weeks, and six months of culture, and beaded cultured pearls were sampled after six weeks, six months, and one year of culture. Mean growth rates of non-beaded cultured pearls remained within a narrow range (0.41 to 0.58 mg d-1), whereas rates of beaded cultured pearl growth increased with time from 0.45 mg d-1 after six weeks to 1.52 mg d-1 after one year of culture. These growth rates are similar to those observed in akoya pearls and lower than those of Tahitian pearls. With a mean shell deposit rate of 0.5 mg d-1, it will take more than a year to produce queen conch non-beaded cultured pearls with a mean weight of 1 ct (200 mg). Beaded cultured pearls larger than 7 mm in diameter can be produced in the queen conch in one year of culture if beaded with 5.1 mm (1.7 bu) nuclei. Because the nucleus is the same used for oyster pearl farming, queen conch beaded cultured pearls are easily identified by conventional x-ray imaging. Similarly, x-ray graphs of non-beaded cultured pearls show the characteristic marks observed in keshi and other pearls originating from tissue grafting only. Grafting success rates for cultured pearl production vary widely, from 10% for freshwater mussels to 70% for black-lip pearl oysters. One-year success rates in queen conch range from 60% to 80%, and will vary depending on factors including conch and nucleus sizes and improvements to the techniques. More than 200 beaded and non-beaded cultured pearls were produced in three years of experiments. Furthermore, post-surgery survival of the queen conch was 100%, and no sacrifice of the animal is required to produce a conch cultured pearl.
In August 2010, Rose Pearl, LLC, was established to introduce conch cultured pearls to the market. Although natural conch pearl scarcity has made production of earrings, matching sets, and necklace strands challenging, the culturing process increases the chances of producing matching pearls. Production of unique jewelry pieces also is a company goal. Investor-supported Rose Pearl is associated with Florida Atlantic University, from which it licenses the technology and receives scientific support. Rose Pearl’s philosophy is to produce a high-quality gem, while helping to raise awareness of the importance of this species to the fisheries, ecosystem, and local cultures. separator
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| Conch Cultured Pearl #166 |
Flame from #166 | Conch Cultured Pearl with bl |
White Conch Cultured Pearl |
Dr. Héctor Acosta-Salmón &
Dr. Megan Davis
About the Speakers
From 2006 to 2009, Drs. Héctor Acosta-Salmón and Megan Davis at Harbor Branch Oceanographic Institute at Florida Atlantic University (HBOI-FAU) became the first and only group to develop a reliable technique to grow queen conch cultured pearls. Rose Pearl, LLC, was launched in August 2010 to commercialize, produce, and market conch cultured pearls. Rose Pearl has a U.S.-based aquaculture facility and works in collaboration with HBOI-FAU.
Héctor Acosta-Salmón, Ph.D., leads Rose Pearl's pearl seeding operations, assists in product development, and manages aquaculture of the conch. He has been working in the fields of pearl culture and pearl quality for more than 12 years and conducted research with all the Western Pacific commercial species of pearl oysters including the akoya, the black-lip, the silver-lip, and the 'mabe' pearl oysters, and also with the rainbow-lip and the Panamanian pearl oysters from the Eastern Pacific. He focused on pearl oyster broodstock management and pearl quality during his doctoral studies at James Cook University in Australia. In 2006-2009, as a researcher at HBOI-FAU he used his pearl oyster culture technology to develop techniques to produce queen conch cultured pearls. Dr. Acosta-Salmón is an associate scientist at Centro de Investigaciones Biológicas del Noroeste in La Paz, B.C.S., Mexico. He holds his M.Sc. and his Ph.D. in aquaculture.
Megan Davis, Ph.D., manages Rose Pearl's production operations and product development, and is responsible for aquaculture of conch during the pearl-culture growout phase. She also plays a vital role with Dr. Acosta- Salmón in seeding the queen conch for pearl growth. Dr. Davis has been working in aquaculture and marine science for 30 years. As co-founder of a commercial queen conch farm in the Turks and Caicos Islands, she developed commercial culture of conch from eggs to juveniles. She joined Harbor Branch Oceanographic Institute at Florida Atlantic University in 1996, and in 2000, she led an effort that succeeded in inducing egg-laying in tank-reared conch, effectively closing the entire life cycle of the queen conch for use in aquaculture. She is the director for aquaculture and stock enhancement at HBOI-FAU. Her aquaculture skills with queen conch provided the necessary technology for the successful culture of queen conch pearls. Her other interests are to develop aquaculture species for food, stock enhancement, and to ease fishing pressure on wild stocks using cost effective, energy efficient, and environmentally sustainable practices. She holds her M.Sc. in Marine Ecology and her Ph.D. in Biology.
Dr. Héctor Acosta-Salmón & Dr. Megan Davis
Aquaculture Facility at Harbor Branch Oceanographic Institute at Florida Atlantic University
5600 US 1 North
Fort Pierce, FL 34946
U.S.A
