اثر درجه حرارت آب بر طول دوره تخم گشايي، شروع تغذيه خارجي،كارايي رشد و بازماندگي لاروهاي تاس ماهي ايراني (Acipenser persicus)

Influences of temperature on hatching time, exogenous feeding onset, growth performance and survival of Acipenser persicus larvae

This experiment was carried out to examine the effect of temperature on egg incubation period, exogenous feeding onset, growth and survival of Persian sturgeon, Acipenser persicus larvae. Experiment was conducted in groups A, B and C at three ranges of temperature (14.5±0.6, 16.3±1.2 and 20.5±1.4 °C, respectively). After fertilization, eggs were placed in the incubation tanks with the same density. Larvae were fed with Artemia urmiana nauplii after absorption of yolk sac, from external feeding time to the fifteenth day after hatch. Data were analyzed at the end of the experiment. The least time for egg incubation was observed in group C (113/3 h). Fish weight was not statistically different on hatching time. But mean body weight was significantly different between groups at the external feeding time and on the 15th day after hatch. Fish in group C had the lowest and the highest weight on external feeding time and 15th day after hatch (38±0.1 and 95±7 mg, respectively). The period of internal feeding and initiation of external feeding was affected by temperature. The longest and the least time for exogenous feeding onset were observed in groups A and C (13.6 and 7.3 days, respectively). Growth parameters in group C were higher than the other treatments. Also, larvae in group B showed the highest survival. The results of this study showed that water temperature has important effect on hatching time, exogenous feeding time, growth factors and survival in Acipenser persicus larvae as increase of temperature caused to increase of growth and decrease in hatching time and exotic feeding onset time.