Japan Atlas: Nature 
Cultivated Pearls

Location: Shima Peninsula of Mie Pref. and the Uwajima area of Ehime Pref. 

 Production of pearls: 
Ehime Pref. 24,051kg (53,023lb); Nagasaki Pref. 14,664kg (32,328lb); Mie Pref. 13,027kg (28,719lb) (1995) 

 Production of mother shells: 
Ehime Pref. 5,555 ton (68.5% of total production of Japan in 1994) 

 Number of pearl culturing companies: 
Total 2,052; Mie Pref. 1,100; Ehime Pref. 607 (1995) 



Jewel of the Sea Cultivated with Scrupulous Care  

Famous the world over, Japanese pearls have gained their reputation since artificial cultivation techniques were established in the 20th century. Pearl culture developed in the Shima Peninsula at the southern part of Mie Prefecture, a place with an intricately indented ria coastline. Here, calm waters of sheltered inlets, gently warmed by offshore currents, provided an ideal environment for pearl culture. Ago Bay, in particular, from ancient times has been a home for pearl oysters, which in Japan are called akoyagai 

Since the development of pearl cultivation which began from around 1910 the region has become to be known to the world as an important center of pearl culture. Located on an island of Kashikojima, the National Pearl Research Laboratory is known as the center for research and development of pearl cultivation technology. Accordingly, as of 1995 1,100 pearl cultivation farms were located in Mie Prefecture; ie. more than one out of two farms were in the region. Today, Mie ranks third on the list so far as the total production of pearls is concerned: main center of pearl production is now shifting towards Ehime Prefecture.  

The Uwa coast in Ehime Prefecture also has a complex shoreline and enjoys mild climate ideal for pearl farming. The area boasts a greater harvest of pearls than anywhere else in Japan. There are two steps in pearl farming; first is cultivation of pearl oysters such as akoyagai. Second step is production of cultured pearls, through insertion of tiny bead around which lustrous nacre is formed. Ehime Prefecture started off by concentrating on production of pearl oysters. Only after the breeding of pearl oysters for pearl culture was widely practiced, people actively took to the next step of actual cultivation of pearls.  

To cultivate pearls, when a seed oyster is two to three years old, a mother-of-pearl bead is implanted into the mature ovary tissue using a special technique. Normally, the oysters are left suspended in the sea from rafts for a year. Then, in winter, when the sea water temperature is low, the shells are opened and the pearls removed. As Japan is at the northern limits for the pearl oyster, if the water temperature falls too low in winter, the oysters must be moved to warmer areas to prevent their pre-mature death. This type of scrupulous care is taken during the cultivation of the pearls. The oysters are also punctiliously tended twice a month, when checks are made for growth of seaweed and other types of mollusk. About 80% of the pearls yielded have commercial value.  

Photo: (top) Gokasho Bay in Mie Prefecture, one of the major pearl production centers (Mie Prefecture); (middle) a view of the Uwa coast area (Ehime Prefecture).  

Unauthorized reproduction of the photos in this page is prohibited. 

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