The Effect of Egg Density on Hatch Rate of Pearl Oyster (Pinctada maxima and P. margaritifera) Larvae

Abstract

This paper reports on two experiments in which the effect of egg density on hatch rate of pearl oyster Pinctada maxima (Jameson) and P. margaritifera (L.) larvae was determined. Fertilized eggs were stocked at densities of 10, 20, 30, 40, 50 and 100 ml· 1 for P. maxima and 10, 20, 30, 50, 100 and 150 mJ-1 for P. margaritifera. After 24 h, the number of D-stage veliger larvae was assessed and survival was calculated. Highest survival was shown at an egg density of 10 mt-1 for both P. maxima (82.5%) and P. margaritifera (93.2%). Lowest survival was shown at a density of 100 ml-1 for both P. maxima (74.1%) and P. margaritifera (79.4%). However, for both species, there was no significant difference in survival between densities of 20 and 50 eggs mi-1 or between 30 and 100 eggs ml-1.