PEARL INDUSTRY 



The pearl industry first began in 1906. The indus- 

 try has developed rapidly after World War II and 

 reached its peak of production in 1967 when 130 tons 

 of pearls were produced by 4,701 culturist (called 

 management units). The increase was related to 

 techniques in artificially collecting seeds and rearing 

 the mothershells (Piiutada sp.). The mother shell 

 industry has grown rapidly since 1952. In 1965. 

 1 1 .000 tons of mother shells were harvested from 

 69,000 rafts operated by 7,859 management units. 



A rapid increase in the number of management 

 units occurred from the postwar era to 1964. These 

 were mostly small-scale units using less than 30 

 rafts. In recent years, the number of units has not 

 been increasing and many units are using more rafts, 

 indicating an enlargement of the individual industry 

 units. 



The everlasting aim of the industry is to improve 

 the quality of the cultured pearl. In the 1920's, pearls 

 were small but, after developing successful tech- 

 niques of transplanting mantle pieces in the gonad, 

 bigger pearls were produced. Between 1952 and 

 1969, the production of small pearls (less than 6 mm) 

 decreased from 67% of the total production to 24%; 

 those in the medium size range (6.0-7.6 mm) and 

 large pearls (7.6 mm) increased in total production 

 from 24 to 58% and from 9 to 18%, respectively. 



As the industry developed, culture grounds 

 spread rapidly over the middle and southeastern 

 parts of Japan. These areas were used mainly for the 

 production of mother shells. In 1956, 82% of all 

 pearls produced in Japan came from the middle 

 Pacific region; 73% of these came from rafts. Re- 

 cently, however, production in this area has declined 

 because of overcrowding and deterioration of cul- 

 ture grounds. In 1964, 20% of the total pearl produc- 

 tion came from the Seto Inland region but, recently, 

 production dropped to 10%. On the other hand, pro- 

 duction in the southern Pacific and East China re- 

 gions has been on the increase, and over half of the 

 total Japanese pearl landings now comes from these 

 two areas. 



Until 1963, yields from pearl rafts were stable but, 

 thereafter, production per raft has gone down. 

 Reasons for this decline have been related to 

 crowded conditions and to the use of unsuitable cul- 

 ture grounds. In the Seto Inland region, the deterio- 

 ration of the waters caused by man-made pollution 

 has caused a drop in yields from certain culture 

 grounds. Special provincial laws have been under- 

 taken to regulate production, recover the balance of 

 supply and demand, and effectively utilize suitable 

 culture grounds. The success of these regulations 

 will insure the steady foundation of the industry and 

 the production of better quality pearls. 



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