50 JUNE 2015 • WORLD AQUACULTURE • WWW.WAS.ORG An independent research project to produce pearls in marine waters with the black-lip pearl oyster Pinctada margaritfera (Fig. 1) was initiated in early 2003 in Andaman and Nicobar Islands, India. Hundreds of trials have been undertaken and thousands of spherical and semi-spherical pearls of 8 to 16 mm were produced in the locally available species of pearl oyster. A natural stock of thousands oysters was available at the seaward side of the project. In floating rafts, hundreds of cages were hung with ropes, and millions of spat settled on the underwater installations and spat collectors, including ropes and cages. Spat of the penguin’s wing oyster Pteria penguin settled at almost the same density as black-lip oysters. Generally, if black-lip oysters are Pearl Culture Advances in the Andaman Islands Ajai Kumar Sonkar abundant during collection of pearl oysters, then other species like the penguin’s wing oyster and/or the Atlantic pearl oyster Pinctada imbricata are relatively scarce. Density was always dominated by one species of pearl oysters at a specific location but the black-lip pearl oyster and the penguin’s wing oyster were both present at about the same density at the project site. Pearls in the black-lip oyster were produced with high efficiency. Penguin’s wing oysters are 6 to 10 inches long, too big to use, but the color of shell interiors is exceptionally lustrous and vibrant (Fig. 2). New Technology Initially trials were carried out to explore the possibilities of producing blister pearls in penguin’s wing oysters. Different shapes, including semi-spherical nuclei, were designed and fabricated. In a series of trials, we implanted 42-mm, Ganesha-shaped nuclei below the mantle of the oysters. These nuclei were cut and carved from the thick portion of shells of edible rock oysters (Fig. 3). Penguin’s wing oysters formed Ganesha image pearls (Figs. 4 and 5). The image of Ganesha has intricate geometrical designs FIGURE 1. Black-lip pearl oysters maintained and conditioned in a laboratory. FIGURE 2. Colors and luster of the shell of penguin’s wing oyster. FIGURE 3. Nuclei cut and carved in the shape of Ganesha from natural shell. FIGURE 4. A Ganesha pearl produced in a penguin’s wing oyster.
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