Morphometrics studies of Mahisefid (Rutilus frisii kutum, Kamensky, ۱۹۰۱) from selected rivers in the southern Caspian Sea

 Mahisefid, Rutilus frisii kutum , is a cyprinid fish which is distributed from Turkmenistan to Azerbaijan along the Caspian Sea. It is one of the economically important fish in the region. As part of the Iranian Fisheries Company’s policy to improve the stocks of this species, every year, fingerling of Mahisefid are released into the southern basin of the Caspian Sea. The main objective of this study was to determine populations in different of rivers. In total, ۳۸۷ fish were collected from four rivers, including Lemir, Sefidrood, Shirrood and Tajan, where this fish migrates for spawning, in spring ۲۰۰۵. Thirteen conventional morphometric factors, ۱۳ ratio and ۱۲ Truss morphometrics were measured and calculated in this study. Conventional and Truss morphometric data were analyzed using two-way ANOVA Principal Component Analysis and discriminant. Average of coefficient of variation (CV%) of morphometric in males was ۱۴.۹۵, ۱۰.۲۸, ۱۷.۴۷ and ۱۶.۵۶ and in females was ۲۱.۳۵, ۱۹.۷۴, ۱۸.۲۵, and ۱۹.۷۴ in Lemir, Sefidrood, Shirrood and Tajan River, respectively, showing that all morphometric characters were significantly different (P<۰.۰۵) among four sampling sites (populations). The first component of morphometrics ۴۴.۳۲% in males and ۶۸.۹۴% in females were positive, indicating that the conventional morphometric was good descriptor of the body shape variation among the populations, especially in females. The total cumulative variances were ۷۶.۶% and ۸۷.۸% in males and females, respectively, suggesting that this can be considered as a useful discriminator. The total cumulative variances were ۶۴.۲۷% and ۶۴.۲۱% in males and females, respectively. The first component of truss was ۸۷.۷% and ۸۱.۳% of the total variance, in males and females, respectively. The results of the present study suggest that each sampling site represents independent population in each river.