抄録
Low salinity rearing of Litopenaeus vannamei requires the transfer of postlarvae (PL) from high salinity hatchery systems to low salinity conditions. In order to determine effective transfer methods, fifteen-day-old postlarvae (PL15) were acclimated from a salinity of 30 ppt to endpoint salinities of 1 and 5 ppt using single-step and gradual salinity reduction procedures. Higher survival rates were obtained with gradual acclimation than with single-step acclimation. Survival of PL15 acclimated to 5 ppt was better than that of PL15 acclimated to 1 ppt. Survival of PL15 and juvenile stages in various low salinity treatments ranging from 0-5 ppt was also compared. In the PL stage, survival rates were good (›85%) in salinities over 1.5 ppt. Tolerance to low salinities increased with age and survival rate of juveniles (65%) was higher than that of PL (2%) in freshwater. In our long-term growth trials of juvenile shrimp maintained in different salinities, optimal growth comparable to that in normal seawater was observed in animals reared in a salinity of 5 ppt, demonstrating that L. vannamei can be successfully cultured in low-salinity inland systems.
