Pearl farming began in Japan at the early part of the century. While the technology was a monopoly of the Japanese for over seventy years, other countries like China, Australia, the Philippines, Indonesia, French Polynesia, and the Cook Islands have cashed in on the multibillion dollar industry in recent years.
Two types of marine pearls are produced for the market which is still much controlled by Japan. The akoya pearls which are cultured in Japan and China are smaller with diameter of three to six millimeters, and are less expensive than the larger South Seas pearls produced in Australia and other countries.
The technology for the culture of pearls is now quite open and accessible to small scale farmers. The technique of grafting a nucleus and with a piece of mantle tissue into the gonad of a full grown oyster for a formation of a pearl through the layering of nacre of “mother of pearl,” however, requires skill.
There are special instruments needed for the operations. Two kinds of oysters are used for commercial production, namely: The silver-lip oyster (Pinctada Maxima) that produces white pearl and the black-lip oyster (Pinctada Margaritifera) that produces black pearl.
Wild oyster stocks are collected from deep sea breeding grounds. With the big demand for the oysters, the decline in the supply of natural stocks have badly affected the industry.
The brood stocks from the wild are made to spawn in the laboratory for the production of baby oysters known as spat which are then reared in grow-out structures suspended three to five meters below the sea.
It takes about two years before the young can grow to a size suitable for pearl production. After implanting the nucleus, the oysters are kept in net baskets that are hung from raft or floats at a depth of six to ten meters.
The oysters are regularly cleaned of fouling organisms every three to four months up to two years. To check whether pearls are being formed or not, some companies use x-ray machines in examining oysters.
Only about forty percent of the grafted oysters produced pearls. Of the pearls that are produced, only fifteen percent will be round or semi-round which command the best prices while seventy seven percent will be of the “baroque” type which have lower value because of their irregular shape and seven and one half percent will not be saleable.
The retail price of for an eleven millimeter high quality black pearl is about US $1200 dollars. Though pearl farming is a lucrative industry, not all is well, due to pollution and it has wipe out fifty percent of its cultured stocks in Japan.
Viral diseases, typhoons and erratic sea temperature brought about by El Niño and algal blooms can also devastate pearl farms.