نوع مقاله : مقاله پژوهشی
1 گروه شیلات، دانشکده منابع طبیعی، دانشگاه گیلان، صومعه سرا، ایران.
2 گروه شیلات، دانشکده منابع طبیعی، دانشگاه گیلان، صومعه سرا، ایران
عنوان مقاله [English]
The bulatmai barbel Luciobarbus capito is an economically important native fish in the southern Caspian Sea basin. Little information on the reproductive indices of this species is available in the lotic ecosystems. Therefore, this study was conducted to investigate the reproductive biology of L. capito in Sefid River. In this study, a total of 239 specimens were caught monthly from Sefid River during a year. Population structure and reproductive factors including age, length, weight, gonadal indices, absolute and relative fecundities were studied, and gonads histological examinations were performed. The age of the studied population (based on scales) was 0+ to 4+ years. The sex ratio of male to female was 1.43 to 1, which was significantly differed from the 1:1. The maximum total length belongs to 4-year-old fish, which belonged to a male specimen with a length of 42cm. The maximum gonadosomatic index for males and females were 1.70 and 4.92 respectively, both in May. The absolute fecundity increased at different ages, so that three-year-old fish had the lowest and five-year-old fish had the highest absolute fecundity. Calculation of ovum diameter showed an increasing trend from January to June, so that the maximum ovum diameter was calculated in June. Egg diameter had a decreasing trend from June to December and its minimum was calculated in December. Histological studies and maturation frequency showed the beginning reproductive season from mid-spring (May). Significant differences were observed between the reproductive indices of this fish in lentic and lotic ecosystems.