Received: 03-09-2014 / Accepted: 02-03-2015
Effects of stocking densities on the growth, survival rate and production efficiency of Meretrix lyrata commercial culture were investigated out in 500 square meter earth pond. Clam seeds (2.45±0.08g in body weight) were stocked at densities of 90, 150 and 210 individuals/m2and reared in a period of 12 months. Results showed that stocking densities did not affect the concentrations of DO, pH, NH4+and chlorophyll-a in culture ponds (P>0.05). Growth rate (0.57-0.60 %/day) of clam reared at 90-150 individuals/m2was significantly (P<0.05) higher than that at 210 individuals/m2(0.48 %/day). In contrast. clam productivity was higher at stocking densities of 150-210 individuals/m2(26.4-27.0 ton/ha) than at 90 individuals/m2(18.8 ton/ha). Survival rates were inversely propotional to stocking densities. The highest profit (138.6 million VND/ha) and benefit-cost ratio (32.13%) were observed at 150 individuals/m2and the lowest values (33.4 million VND/ha and 9.01%, respectively) at the density of 210 individuals/m2. This study suggests that the suitable stocking density in the earth pond culture of M. lyrata should be is 150 individuals/m2.