Results of SFA preliminary experiments on artificial spat collection of the black pearl oyster Pinctada margaritifera
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Forty oyster spat collector bags were submerged at two different sites near Mahe island fofr a period between 3.2 and 11 months. Strong currents in the south-east monsoon period resulted in a few bags lying in the sand which was detrimental to spat settlement. The mean settlement rate was calculated at 15.6 oysters per bag, however 71_310= of the bags had more than 10 oysters per bag. Considering only those bags, the settlement averaged at 27 oysters per bag. The sizes of oysters in collector bags after different soaking times, indicate that growth rate in the first few months is higher than on French Polynesia. Growth rates of oysters maintained in a cage indicated an average increase of 21.7 mm in five months, between the size of 25.9 mm and 47.76 mm. The observed mortality over the same period was 29.2_310=. Oyster spat settlement did occur all year around, indicating that spawning also occurs all through the year. Pearlculture in Seychelles is technically feasible and pearl farms will depend,for their regular supply of oysters, on collecting methods of oyster spat produced by natural stocks. Natural oyster beds are reported to be limited in Seychelles and these beds are presently exploited for the supply of the artisanal craft industry and the jewellery industry. Suitable sites for farming operations, on the granitic and on the outer coraline islands, are limited. In view of these limitations, priority has to be given to the assessment of the actual status of oyster beds and then implement neccessary of the actual measures where needed. The continuation of the Sfa training and research program regarding optimum sites, settlement rates, growth rates and other biological information will be crucial for the future development of the industry.The successful development of the pearl oyster industry in Seychelles, will largely depend on the choice of adequate management options, concerning the resource as well as the potential commercial ventures. A guideline on pearlculture development has been produced to support future initiative in this field.
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