FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

This study was conducted to compare the survival and growth of white leg shrimp, Litopenaeus vanname, cultured in three types of indoor multi-layer net cages, namely double-, triple-, and hexa- net cages of the same volume. Total rearing duration was 57 days, with an initial density of 64/m2 for each layer. Salinity and water temperature were maintained at 25 ± 1 ppt and 29.1-31.6°C, respectively. The initial body weight of the shrimp was 0.15 g. Results indicated that the hexa-layer net cage was the best for spatial usage of the entire volume of water, with a total production 1.33 and 2.44 times that of the triple- and double-layer ones, separately. The average survival rates of each layer in the hexa- (75.9%), triple- (73.4%), and double-layer (80.5%) net cages did not significantly differ (p > 0.05). There were no differences in harvest size among the three treatments, either. However, the proportion of large-sized shrimp was highest in the hexa-layer cage among the three types of cages. The feed conversion ratio was less than 0.5, and the reasons for this notable result are also discussed.