Light intensity preferences of 5-month and 7-month F2 Chinese sturgeon (Acipenser sinensis)

After the success of completely controlled propagation in Chinese sturgeon( Acipenser sinensis),it is necessary to find out the possible behavior variation between wild group and second generation. We combined individual test and population test in 3 different experiments: test of substrate color preference,illumination intensity preference and the optimum illumination. The results showed that both 5-month and 7-month juvenile F2 A. sinensis significantly chose white substrate( 95% Confidence interval of preference on white substrate does not contain 50%). 5-month juvenile F2 A. sinensis individuals significantly chose illuminated area( 200-250 lx)( P 0. 05),while 7-month ones significantly chose transition area( 20-50lx)( P 0. 05). Both 5-month and 7-month juvenile F2 A. sinensis populations preferred transition area( 20-50 lx)( P 0. 05) in population test. The different choice of illumination intensity preference between individuals and population in 5-month F2 A. sinensis may be related to ‘signal-adaptation hypothesis' and the optimum illumination range. 5-month juvenile F2 A. sinensis significantly chose illumination area of 45-135 lx( P 0. 05); 7-month juvenile F2 A. sinensis significantly chose illumination area of 23-202 lx( P 0. 05). It meant that with the increasing age,F2 A. sinensis strengthened its adaptability to illumination. From all above,both 5-month and 7-month juvenile F2 A. sinensis preferred white substrate,and the optimum illumination range was 20-200 lx. Compared with the existing wild juveniles data,their phototaxis has already declined.