Abstract: Two culture systems were designed to classify the effects of intensity-stress and water quality factors on the growth of shrimp. In the first system, shrimps Litopenaeus vanname, were cultured at 150, 300, 600 and 900 individuals/m3. In the second system, shrimps were cultured　with water drained from the first system. The growth, survival and non-specific immunity factors (PO、SOD、POD、Ua and Ul) of shrimp cultured in each system were determined. The results showed that weight gain, length gain and survival rate reduced with the increase of stocking intensity in the first system. Survival rate, weight and length gain, the activities of PO、POD、Ua and Ul of shrimp in the second system were higher than those of shrimp cultured in the first system, but SOD activity of shrimp in the first system was higher than that of the second system. There are no significant differences in water quality factors (TAN、NO2-N、NO3-N and PO4-P et al.) between the two systems, which suggested that the primary reason for the difference of shrimp growth and enzyme activities in the two systems was intensity-stree, while water quality only played a minor role.

Key words: Litopenaeus vannamei, intensity-stress, growth, non-specific immunity factor