Survival, Growth, and Feed Utilization of Pre- and Postmetamorphic American Shad Exposed to Increasing Salinity

The American shad Alosa supidissima is currently in emerging aquaculture species in China, and establishing conditions required for optimal growth will play a key role in future development of American shad Culture. We evaluated the effects of increasing salinity concentrations on survival, growth. and feed utilization of American shad in two separate 30-d experiments. In experiment 1, 25-d-old. premetamorphic fish (mean weight +/- SD = 0.07 +/- 0.04 g) were exposed to 0, 10, 20, and 30-ppt salinity (26-29 degrees C). In experiment 2, 80-d-old. postmetamorphic fish (1.46 +/- 0.52 g) were exposed to 0, 5, 10, 20, and 30-ppt salinity (21-26 degrees C). Mortality was markedly higher at salinities of 20 ppt (52% and 74%, respectively. for pre- and postmetarnorphic fish) and 30 ppt (100% and 90%, respectively) than at 0 and 5 ppt (< 1%). Specific growth rate (SGR) and feed conversion efficiency (FCE) were highest at 0-ppt salinity for premetamorphic fish (SGR = 8.81% per day; FCE = 1.12) and in 5-ppt salinity for postmetamorphic fish (SGR = 4.59% per day: FCE = 0.87). The SGR and FCE were lowest at 30-ppt salinity, and a significant negative relationship was demonstrated between salinity and SGR and between salinity and FCE. In both experiments. SGR and FCE were positively correlated. Our observations demonstrate that culture of young American shad may be possible all salinities up to 10 ppt, but 0-5-ppt salinity produced the best growth.