Saeed Hajirezaee

To compare the reproductive performance of spring and autumn forms of Persian sturgeon males, Acipenser persicus, the relative abundance of spermiating and non-spermiating males, milt quality, sex steroids and cortisolwere investigated after pituitary preparation (PP) treatment and at the time of spermiation. Our results showed that higher numbers of spring males are spermiated after PP treatment thanautumn individuals.The autumn spermiatingmales had higher and lower values of sperm density and duration of motility than spring males respectively. The milt volume was higher in spring males than in autumn individuals. The percentage of motility was statistically equal in both the groups examined. In both forms of brooders, the serum levels of testosterone (T),11-ketotestosterone (11-KT), progesterone (P),17a, 20b, 21-trihydroxy- 4-pregnen-3-one (20bS) and cortisol (C) increased after PP treatment, although such increases did not occur in non-spermiating males. Our results showed the probable involvement of 20bs, P,T, 11-KT and C in the ¢nal maturation of Persian sturgeon. In addition, it was demonstrated that the spring form of Persian sturgeon shows better reproductive performance than the autumn form in terms of a response to arti¢cial induction and milt quality.