Research >> Mariculture
Pearl Culture in the Maldives
In 1996 MRC started the first pearl culture activity as Pearl Culture Pilot Project with financial assistance from the United Nations Development Programme (UNDP). When this five year project ended MRC and UNDP started in 2003 a follow-up five year project - Pearl Culture Demonstration, Extension and Marketing Project (PCDEMP), which will last until December 2008.
The project activities of PDEMP include refining pearl culture techniques developed by the previous pilot project; conducting training in pearl farming and jewellery making, and marketing jewellery. Pearl culture techniques have been refined. Pearl farming and jewellery making training, and commercialization activities are on-going.
The main steps in pearl culture are:
- collecting oyster spats (young oysters)
- growing oysters
- culturing pearls
- harvesting pearls
Two pearl oyster species occur in Maldivian waters. They are Penguin Shells [a] (Pteria penguin) and Blacklip Oyster [b] (Pinctada margaritifera). Out of these two species Penguin shell is more abundant. PDEMP is culturing pearls in Penguin Shell.
To get oysters for pearl culture spat collectors are hanged from floating rafts [a]. Spat collectors are usually plastic nets made into cylindrical shape [b]. These pieces of nets are fastened to a rope, which can be hangeddown from floating rafts [c]. Spats or young oysters attach themselves to the spat collectors and grow.
When the spats on the collectors are about 6 months old the collectors are removed from the rafts and taken out of the water. Spats on the collectors are detached from the nets. A whole is made in one corner of the oyster shell, a length of fishing line is passed trough the whole and the oysters are fastened to a length of rope using the fishing line. The lengths of rope with a single oyster on each length are then tied to each other to make an oyster line. The oyster lines are taken to the sea and hanged down from floating rafts for further growing the oysters. It takes another 12 months to grow oysters to a size suitable to insert a pearl nucleus.
The next step is inserting pearl nucleus into the oysters. A pearl nucleus is an object (for example, a sand particle, a parasite egg) around which nacre (shiny material) or mother-of pearl is laid down. When a foreign body (nucleus) gets between the inner surface of the shell and the mantle tissue (nacre creating tissue) the oyster gets irritated. The oyster tries to get rid of the foreign object out of the shell. If it cannot bring the object out, it creates shiny layers (nacre) around the object. As time passes thick layers of nacre are deposited on the object, and the object then becomes a pearl.
To put the nucleus the oysters on the raft are brought to land and kept in a quiet place. When an oyster opens its shell a shell opener (lever) is placed between the two halves of the shell, and the shell is further opened by a small force. A piece of wood is placed into the shell to prevent closing and the shell opener is then removed. Next a semi-spherical piece of plastic (nucleus) is glued onto the inner surface of the oyster shell.
As the operated oysters grow the pearls grow in them. It takes about 12 months (from the time of operation) to grow a small (9-10 mm diameter) pearl. By this time the operated oyster is 30 months old. It takes about 18 months (from the time of operation) to grow a large pearl (12-15 mm diameter). By this time the operated oyster is 36 months old.
The finally the cultured pearls are harvested. The operated oysters are taken to land and opened.The tissues and internal organs of the oysters are removed and the shells are cleaned. The pearl can be removed by cutting the shell around the pearl. The pearls and shells are now ready to make jewellery out of them. Two types of raw materials are available for making jewellery - pearls and shell (mother-of-pearl).
For more information please contact: Hassan Shakeel at MRC