Study on the population dynamics parameters of spirlin (Alburnoides eichwaldii) in reservoir of Shahid Rajaii dam, Sari

In this study of the some parameters of population dynamics of spirlin (Alburnoides eichwaldii) was performed in reservoir of Shahid Rajaii dam in four seasons. 226 specimens were caught by gill nets, were in 5 age groups 0+ to 4+ years that, 2-year-olds were prevailing in both sexes. The sex ratio of males to females were 1:3.17, that, indicates the predominance of the female sex (p<0.05, χ2=60.84). Specimens ranged from 62 to 131 mm in length and 2.59 to 30.46 gr in weight. In overall, the length and weight of the females was higher than males (p<0.05). The growth pattern was calculated as positive allometric according to the slope of the regression line between length and weight and based on the Pauly growth equation. The Von Bertalanffy growth equations for males and females were calculated respectively   and   that the infinity length in females was more than males. The condition factor almost was equal in both sexes (p>0.05). The average absolute and relative fecundity were 2690±1048 and 193±98 respectively. The average of female egg diameter was 0.86 ±0.21 mm in this study. Examination of the nutritional index showed the tendency of this species to eat carnivores. After 15 years of the formation of the lake, the view of many dynamic parameters of Alburnoides eichwaldii in reservoir better than river.