THE TEMPERATURE EFFECTS OF THE EMBRYONIC PERIOD OF THE PERSIAN STURGEON (ACIPENSERPERSICUS)

Regulation of water temperature is a major factor affecting the embryonic development of fish species. We examined effects of five temperatures, from 13°C to 23°C on three embryonic phases including cleavage, neurolation and hatching in Persian sturgeon (Acipenserpersicus) from March to May 2006. After obtaining mature Persian sturgeon (five females and three males) transport them to the Aquaculture Center of Aghghala in Golestan province. The temperature effects on the three embryonic period's cleavage, neurolation and hatching keeping other physical and chemical factors constant were examined. The maximum hatching was in 15°C and the minimum abnormality was in 15°C and 16°C and also, the maximum mortality was seen in 21. 5°C. It is concluded that temperatures between 15°C to 18°C are the upper limit of the thermal optima for Persian sturgeon embryos. Abnormalities observed in this research included edema of the pericardial cavity, notochord curved downwards (lordosis) or upwards (kyphosis) which affected mobility of the hatching embryo.