SEASONAL FLUCTUATIONS OF SEX STEROIDS (TESTOSTERONE, 17 α-HYDROXY PROGESTERONE AND 17 β-ESTRADIOL) WITH SEXUAL DEVELOPMENT IN FARMED STELLATE STURGEON, ACIPENSER STELLATUS

Samples were collected from 24 farmed Acipenser stellatus (7 years old) including 14 females and 10 males during summer 2005 to spring 2006 in the International Sturgeon Research Institute (Rasht, Iran). Testosterone levels showed significant different in males at the stage IV (P<0.05). Minimum rate of Testosterone was 9.21±5.7ng/ml in winter and its maximum was 556.3±45 ng/mlin spring, and 17a-hydroxy progesterone levels in males showed chaotic fluctuations in different seasons. 17b-estradiollevels in males and females at the stage IV showed significance difference in various seasons (P<0.05) and in males it was at its minimum (1.36±1.3ng/ml) in spring and its maximum (4.4±1.2ng/ml) and in females it was minimum (2.65±84ng/ml) in spring and maximum (31.5±8.6ng/ml) in autumn. We found no significant differences in male and female hormones levels at the stages II, III and III-IV in different seasons. Comparison of Testosterone and 17a-hydroxy progesterone in males and females showed that Testosterone level was more than progesterone at similar conditions. Based on the results, sex steroid hormones, Testosterone, 17a-hydroxy progesterone and 17b-estradiol hormones are the three most important indices of sexual maturation that could be used for sex identification of the sturgeons at rearing conditions.