Sara koohilai - Department of Marine Biology, Graduate School of Marine Science and Technology, Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran.
shahrbanoo oryan - Department of Marine Biology, Graduate School of Marine Science and Technology, Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran.
Homayoun Hosseinzadeh Sahafi - Department of Marine Biology, Graduate School of Marine Science and Technology, Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran.

Rutilus frisii kutum (Caspian Kutum) is mentioned as one of the most valuable fish in Caspian Sea. From March to May this species migrates to shallow river waters for spawning. Overfishing, water pollution increasing and degradation of river beds are mentioned as threatened factors by the Iranian Fisheries Organization. The aim of present study was to evaluate the effects of gonadotropin-releasing hormone (GnRH) analogue (Buserelin) at different doses with Ovaprim on final oocyte maturation, ovulation and spawning in Caspian Kutum. So 45 Adult females were selected randomly and injected once with Buserelin Acetate (BUS) and divided into 5 groups (n=9). Group 1: (BUS) 5 μg kg-1 BW, Group 2: (BUS) 10 μg kg-1 BW, Group 3: (BUS) 20 μg kg-1 BW, Group 4: Ovaprim, 0.5 ml kg-1 BW (positive Control), Group 5: Intact (negative Control). Our results showed that the highest mean value in ovulation success, ovulation index, fertilization success, relative fecundity and the number of eggs belonging to the Ovaprim treatment. On the other hand, spawning was more successful in BUS 5 μg kg-1 (67%) treatment than the other doses. Therefore, it could be concluded that BUS 5 μg kg-1 as an optimum dose induced ovulation and spawning in Kutum, so BUS 5 μg kg-1 as well as Ovaprim (sGnRHa combined with domperidone) is preferred for ovulation and spawning induction in this species.

Caspian Kutum; GnRHa; Ovaprim; ovulation success; Final oocyte maturation