مطالعه روند رسيدگي تخمدان و برخي از شاخص هاي گنادي ماهي سفيد درياي خزر(rutilus frisii kutum kamenskii,1901) در استان گيلان (ناحيه بندر كياشهر)

The trend of ovarian development and some gonadal indices in Kutum {Rutilus frisii kutum Kamenskii, 1901) from Bandar-e Kiyashahr Southwestern of Caspian Sea

Studies were conducted on the changes occurring in the ovaries of adult female Kutum, (Rutilus frisii kutum Kamenskii, 1901) in Bandar-e Kiashahr in Southwestern of Caspian Sea during a yearly cycle (between two spawning period) from October 2007 to April 2008. No abnormalities or pathological changes in the ovarian or body of the investigated fish were detected. The aims of this study were to confirm timing, frequency and duration of the spawning period, to monitor changes in the gonado-somatic index(GSI), to relate (GSI) to the histological characteristics of the ovaries and to describe the stages of Kutum oocyte and ovarian development. Ovary samples were taken monthly and processed to with H&E and later were studied by light microscope. Different stages of oocyte development (nucleus changes, oocyte diameter and forming of yolk vesicle, yolk granules and lipid droplets) were surveyed. Six maturity stages were observed during our study that included: Virgin stage (I), Maturing virgin (II), Developing (III), Gravid (IV), Spawning (V) and Spent (VI). This study has shown that gonadosomatic index (GSI) began to increase in March and reached the highest value (29.47±4.2) in April and then decreased sharply in early may. According to the results obtained gonadal development of Kutum was synchronous type.