Abstract

• Species Pinctada maxima (Jameson,1901) is one of four major pearl oyster species utilized by the cultured pearl industry for pearl production. They are rich in the banks of Mergui Archipelago in the Andaman Sea. Thermal stimulation is a successful spawning induction in all major commercial pearl oyster species in hatchery. In the present study, the induce spawning method on hatchery of gold-lip oyster and silver-lip oyster Pinctada maxima was used for larval and spat oyster culture conduction in Myanmar Pearl Enterprise, Pearl Island, Myeik Archipelago. Different developmental stages of larval oyster were found after the fertilization in the hatchery such as cleavage stage, trochophore stage, D-shape stage, umbo stage, eye-spot stage and spat stage, etc. the time was taken from the selection for mother oysters until the spat collection stage was for 22days. The measurements of larvae were 80-90 µm with the mean size 87.6 µm in gold-lip oyster and 90-110 µm with the mean size 105.2 µm in silver-lip oyster on six days after fertilization. After 20 days, the size of measurement was increased to 170-260 µm with the mean size 234.4 µm whereas 180-280 µm with the mean size 243.0 µm for gold-lip and silver-lip oysters respectively at the optimal environmental condition in hatchery.