The effect of photoperiod duration on hatching rate of eggs in wild Persian sturgeon (Acipenser persicus)



BACKGROUNDS: The Persian Sturgeon (Acipenser Persicus) is an indigenous and most populous sturgeon in the southern coasts of the Caspian Sea. Nowadays, their numbers are decreasing due to certain problems that are affecting their early life. OBJECTIVES: The aim of this study was to take up the optimal photo period in hatching stage of wild Persian sturgeon eegs. METHODS: One female (weight of 38kg and length of 178cm) and one male (weight of 15kg and length of 145cm) spawner of Persian Sturgeon were selected with the female the male having a after fertilization there were 3 kg of eggs (with a 92% fertilization rate). The fertilized eggs were transferred to 12 boxes of Youshchenkov's incubators with different lighting treatments as follows: control treatment (12 hrs of light and 12 hrs of darkness); treatment one (8hrs of light and 16 hrs of darkness); treatment two (24hrs of light); and, treatment three (24hrs of darkness); considered 3 replications for each treatment. Thick aluminum foil was applied to create a dark condition for each incubator box. Statistical analysis was done using ANOVA test followed Tukey's test. RESULTS: The results showed no significant difference for the hatching rate in the four different treatments (p>0.05), but, the hatching rate in treatment three was higher when compared with the other groups (48.65±7.53%). The results also showed that the mean weight of larvae in treatment three was more than the other ones (101.14±4.25g). In treatment three, the number of larvae per gram was less than the other treatments (48 per gram), with no significant difference (p>0.05). CONCLUSIONS: It can be concluded that in the incubation stage, Persian Sturgeon (Acipenser Persicus) is more adaptable to darker conditions, hence providing dark conditions in the incubation period is necessary to obtain a larger quantity of high quality larvae.