Journal of Fishery Sciences of China (中国水产科学) 2013/20:6 PP.1204-1211
Chinese sturgeon (Acipenser sinensis) is a species of anadromous migratory large fish living for decades, and is a special rare fish in China. In 2009, we got the second filial generation (F2) from the F1 of this species by complete artificial propagation under fresh water, which meant China got successful progress in conservation of A. sinensis. But the question is if there exists difference in biologic characteristics between the wild species and artificial F2. In this study, we tested the response of larval A. sinensis F2 to four light intensities (100, 320, 960, and 1 920 lx), and two modes of illumination (dark and surface light source). The phototactic behavior of each individual was observed for 30 min/d for 24 consecutive days. Between 0–8 d after hatch (dah), the individual ratio of phototaxis movement in the groups under the dark treatment and surface light source illumination was significantly lower (P<0.05) than for those exposed to the point light source. Furthermore, the individual ratio under the point light treatment increased with increasing light intensity, and there was a significant difference in the ratio at 320 lx and 1 920 lx or 100 lx (P<0.05). At 8 dah, there was evidence of larval phototaxis at all four point light source intensities, though phototaxis was significantly higher at 100 lx than at 960 lx (P<0.05). The larvae were positioned on the bottom of the plastic jar and did not exhibit any significant phototaxis. Our results suggest that the second filial generation of Chinese sturgeon larvae are very sensitive to weak light between 0–8 dah, and gradually lose phototaxis after that time. This is consistent with observations of phototactic behavior in wild Chinese sturgeon larvae.