Abstract:To investigate the effects of different photoperiods on the growth, gonadal development, and hemolymph biochemical composition in Exopalaemon carinicauda, samples with a mass of (0.71±0.05) g and body length of (3.62±0.28) cm were studied under a water temperature of 23~25℃, salinity of 22~24, pH of 7.8~8.1, and illumination intensity of 1000 lx. The growth, gonadal development, and hemolymph biochemical components were measured under five photoperiods (where L, illumination duration; D, dark duration; whole-day illumination L, 16L:8D, 12L:12D, 8L:16D, and whole-day dark D). Results showed that the D group had the highest numerical survival rate (86.67±5.77)%, followed by 12L:12D group, the survival rate was (83.33±8.82)%, the survival rate of group 8L:16D was (80.00±3.33)%, with no significant difference between these three groups (P>0.05). The specific growth rate of group 8L:16D was (2.49±0.20)%/d, significantly higher than that of group D (P<0.05). The molting rate of group 8L:16D was the highest [(6.96±0.50) sub/(tail·d)]. The gonadal index increased gradually with a decrease in illumination time, and reached the highest value at 8L:16D [(2.37±0.04)%], significantly higher than that in other groups (P<0.05). The ovarian maturation rate of group 8L:16D was (42.93±4.57)%, significantly higher than that in group D (P<0.05), and the relative length of the ovary in group 8L:16D was significantly higher than that in other groups on the 30th day (P<0.05). The levels of protein and cholesterol in the hemolymph of group 8L:16D were significantly higher than those of group L, group 16L:8D, or group D (P<0.05), but there was no significant difference with group 12L:12D (P<0.05). The glucose concentration of group 8L:16D was significantly higher than that of group L and group D (P<0.05), but there was no significant difference with group 16L:8D and group 12L:12D (P>0.05). The triglyceride concentration in group 8L:16D was significantly higher than that in the other groups (P<0.05). The results showed that the growth, gonadal development, and hemolymph biochemical components of E. carinicauda were affected by the photoperiods. 8L:16D was the most suitable photoperiod for E. carinicauda ripening and factory farming.
