PROBLEMS IN PEARL OYSTER Pinctada maxima SEED PRODUCTION IN INDONESIA  

Indonesian south sea pearl production contributed significantly to the global pearl trade. In 2014, export value of Indonesian pearl reached to 28,740,108 USD, accounted for 1.42% or ranked ninth of the world trade (comtrade.un.org). However, there were problems in the production of south sea pearl most importantly in seed production. The availability of mature broodstock, loss of genetic diversity of the broodstock, and significantly low survival of larvae are determined as major problems. This paper signifies these problems in regard to improve the quality and the production of pearl oyster P. maxima seed.

Firstly, mature female and male broodstock were not available year round. Female were only ripe from September to October (Fig.1). Therefore, spawning and larval rearing could not been done every month. It is suggested to manage broodstock for maturation in controlled conditions such as use of high nutritional live feeds, and perform hormonal induction.

Next, loss of genetic diversity of the broodstock has been found in pearl oyster hatcheries. As we can see in Table 1, heterozygosity value of the first generation (F1) broodstock was lower than that of the wild broodstock (F0). The loss of genetic variations was probably caused by inbreeding depression.

Lastly, low survival rate during larval rearing is the critical problem in seed production. Survival rate of the larvae is generally <10% at the end of larval rearing (Fig.2). High mortality was observed during critical larval stages such as metamorphosis between developmental stages.