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Pinctada contributes famous ‘Pearl fisheries’ of the Persian Gulf, Gulf of Mannar and Gulf of Kutch. It also exists in Mexican Gulf and Australian Waters. On Indian coasts, they are found in the ridges of rocks in Gulf of Mannar between the range of kilakarne to Cape comorin at 15.20 fathoms depth. In Palk Bay, oysters are found in sandy bottom, while in Gulf of Kutch they are available on the intertidal reefs. According to Nishikawa’s theory, when any foreign particles enters in the body of the pearl oyster, it will give irritation and the animal will try to remove or neutralise the irritation, when mentle will secrete "Nacreous liquid" which on coming in contact with sea water solidifies and known as pearl. When the animal is captured from its original ground with a pearl, it is known as natural pearl. Cultural pearl is produced by catching young oysters and introducing a foreign particle and watching it under enclosed cage for about 3 years. The difference between natural and cultural pearl is known by ‘X’ rays. Pearl fisheries in the Gulf of Mannar is under the control of Tamil Nadu Govt. The pearl fisheries are not operated regularly in Gulf of Mannar and the fishery is stopped since 1962. In past also, after a gap of 27 years the fishery was resumed in the year 1955 and continued upto 1962. During the period the average annual catch of oysters was 10.83 millions. The year 1958 was the best year, when 21.48 million oysters were collected giving a net income of Rs. 465 thousand to the State Govt. Pearl Oyster yields about Rs. 30,000 on an average per fishery in Gulf of Kutch. The maximum numbers of oysters collected was 76,685 in the year 1916-17 and a minimum number of 522 oysters were collected during 1936-39. The Gulf of Kutch pearls are not only greatly valuable, but their pearl yielding capacity is also greater than those of Gulf of Mannar in Tuticorin. |
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