EFFECTS OF STOCKING DENSITY ON GROWTH AND SURVIVAL OF EARLY JUVENILE SILVER-LIP PEARL OYSTERS, PINCTADA-MAXIMA (JAMESON), HELD IN SUSPENDEDNURSERY CULTURE

This study investigated the effects of stocking density on the growth and survival of juvenile silver-lip (or gold-lip) pearl oysters, Pinct ada maxima. Spat were resettled onto PVC slats (75 x 500 mm(2)) and he ld in suspended nursery culture for 6 weeks at four stocking densities : ten juveniles per slat (1.3 juveniles per 100 cm(2)); 50 juveniles p er slat (6.7 juveniles per 100 cm(2)); 100 juveniles per slat (13.3 ju veniles per 100 cm(2)) and 150 juveniles per slat (20 juveniles per 10 0 cm(2)). Best survival was recorded at a stocking density of ten juve niles per slat (80 +/- 4.36%, mean +/- s.e.) which was significantly h igher than the other densities tested (P < 0.05). Survival did not dif fer significantly between the other densities tested (P > 0.05). Best growth, measured as wet weight, shell length and shell height, was sho wn at a density of ten juveniles per slat, where wet weight and shell length were significantly greater than at any other stocking density ( P < 0.05). Shell height was also significantly greater at a density of ten juveniles per slat than at all other stocking densities with the exception of 50 juveniles per slat. Spat were significantly (P < 0.05) smaller at each increase in stocking density from 50 juveniles per sl at to 150 per slat. The incidence of growth deformities increased with increasing stocking density. These increases were significant (P < 0. 05) between all densities apart from 100 juveniles per slat and 150 pe r slat, where the difference in the number of deformed animals was not significant(P > 0.05). The ratio of shell height to shell length was also influenced by stocking density. Differences between the shell hei ght:shell length ratios were significant between all stocking densitie s (P < 0.05) except 100 juveniles per slat and 150 juveniles per slat, where there were no significant differences (P > 0.05). (C) 1997 Else vier Science B.V.