Effect of gender on Akoya pearl quality

During the cultivation of pearls, a mantle piece and pearl nucleus are transplanted into a recipient Akoya pearl oyster (Pinctada fucata). The gonad has been the area of transplantation since pearl culture techniques were originally developed. Transplantation into gonads without germ cells is vital for the production of high-quality pearls. Almost all pearl cultivators thus perform forced elimination of the germ cells from the gonads before transplantation. However, little attention has been paid to the sex of the pearl oyster, even though the gonad state is vital for the production of high-quality pearls. In our present study, we investigated the relationship between the sex of the recipient Akoya pearl oyster and pearl quality. We found that the rate of production of commercially valuable pearls was higher for male than for female recipient oysters. Furthermore, the nacre in male recipient oysters grew evenly every month whereas it was added less uniformly in female recipient oysters. Nacre growth in female pearl oysters was found to be related to ovarian development. These results indicate that differences exist in the pearl formation ability of male and female Akoya pearl oysters. By understanding the relationship between the sex of Akoya pearl oysters and pearl quality, high-quality pearls could be cultivated with better efficiency.