Factors influencing the quality of half-pearls (mabe) produced by the winged pearl oyster, Pteria penguin (Roding, 1758)

摘要

The winged pearl oyster, Pteria penguin, is cultured primarily to produce half-pearls (mabe). The mabe quality is influenced by culture techniques, but there is limited information in this field. P. penguin with mean (+/- SE) dorso-ventral height of 250 +/- 6.5mm were used to investigate the influence of culture period and nucleus position on mabe quality. Oysters were relaxed using 1-propylene phenoxetol, and five nuclei were glued at different positions to the inner surfaces of the oyster shells; three on the more concave left valve and two on the right valve. Nucleated oysters were then cultured for 10months under commercial pearl farming conditions at Savusavu in Fiji. Nacre deposited at the base and top of the nuclei was measured monthly, from the 6th to the 10th months of culture and the different qualities of mabe produced at different positions were scrutinized. Nacre thicknesses at the base and top of the resulting mabe were significantly different at different months (P<0.05) and the rate of nacre deposition was highest during the warmer months. The different positions of nuclei on the valve greatly affected the quality of mabe formed. After a 10-month culture period, around 1mm of nacre covered the nuclei although the best quality mabe were obtained after 9months.