Growth and Physiological Response of Litopenaeus stylirostris Acclimated to Low Salinity

Juveniles of wild Pacific blue shrimp Litopenaeus stylirostris (mean initial weight ± standard deviation = 1.5 ± 0.1 g) were acclimated from a natural seawater salinity of 35‰ to salinities of 0, 2.5, 5.0, 7.5, 10, 15, and 25‰. After reaching the desired salinities, L. stylirostris were cultured for 32 d and growth, feed conversion ratio, and survival, as well as hemolymph and culture water osmolality, were determined. The L. stylirostris exposed to 0‰ died before or shortly after reaching the salinity end point. Final mean body weight of L. stylirostris held at 2.5‰ (3.1 ± 0.8 g) was significantly reduced compared with all other treatments. In contrast, those held at salinities from 5‰ to 35‰ had similar performance, with mean body final weight ranging from 3.8 to 4.5 g, showing that L. stylirostris can be cultured across this range of salinities without adversely affecting growth, survival, or feed conversion ratio. Litopenaeus stylirostris is a euryhaline organism, able to maintain its hemolymph osmolality relatively constant despite changes in salinity. The isosmotic salinity of L. stylirostris, estimated from the point of intersection between the regression lines of water salinity versus water osmolality and water salinity versus hemolymph osmolality, was 26.7‰. Litopenaeus stylirostris is an efficient osmoregulator with potential for low-salinity culture.