Effects of larval set density on subsequent growth and survival of the silver-lip pearl oyster Pinctada maxima (Jameson)

Pediveligers of the silver-lip (or gold-lip) pearl oyster, Pinctada maxima, were placed in 15 settlement vessels at densities of 0.5, 1.0, 1.5, or 2.0 larvae/mL 16 days after fertilization. The number of settled spat per 100 cm² was estimated on Day 23 and again on Day 44. The number of spat/100 cm² in the 1.0 larva/mL treatment was over double, and significantly greater (p < 0.05) than that in the 0.5 larva/mL treatment. Increases in the number of spat per 100 cm² were not significant (p > 0.05) between larval densities of 1.0 and 1.5 larvae/mL and 1.5 and 2.0 larvae/mL. Highest mean survival was observed in the 0.5 larva/mL treatment; however, this was not significantly greater (p >0.05) than that in other treatments. By day 44, spat from the 0.5 larva/mL treatment had a mean antero-posterior shell length (SL) of 1.87 ± 0.08 mm and were significantly larger (p < 0.05) than spat in all other treatments. Spat in the 1.0 larva/mL treatment were significantly larger (p < 0.05) than those in the 1.5 or 2.0 larvae/mL treatments. Differences in Si between the 1.5 and 2.0 larva/mL treatments were not significantly different. Differences in size were most likely attributable to competition for space and food. Based on the results of thisstudy, a setting density of no more than 1.0 larva/mL is recommended for P, maxima. To maximize survival and growth of P. maxima spat, a density approximating 70 spat/100 cm² is recommended