Growth and reproductive characteristics of Squalius Lepidus Heckel 1843 in the Dimeh spring of Zayandeh-Rud River

Population structure, growth, and reproductive characteristics of Kavar, Squalius lepidus, a native species of Cyprinidae family in Zayandeh-Rud River were investigated by monthly sampling from October 2006 to August 2007. A total of 415 individuals were collected. Age groups of males and females ranged between 1+ and 4+. The male:female sex ratio was 1:3. The largest female was 163.0mm in fork length and 63.71g in weight whereas the largest male was 156.0mm in fork length and 50.45g in weight. The minimum, maximum, and mean absolute fecundity was 1161, 12953, and 4279±2169, respectively, and relative fecundity was 148.4±49.3 eggs/g of body weight. Gonadostomatic Index (GSI) values suggested that spawning of Squalius lepidus occurs from May to June. Thus, Squalius lepidus is considered an intermittent spawner species. Growth parameters for both sexes were stated by the von Bertalanffy growth function as k = 0.162, L = 232mm, to= -0.427 years for females and k = 0.136, L =217mm, to =- 0.847 years for males. The weight-length relationship was described as W = 0.00005L2.827 (r2 = 0.860) for males andW = 0.00005 L 2.855 (r2 = 0.859) for females. The slope of the regression line (b) fitted through the weight-length data suggested a negative allometric growth for both females and male (P<0.05).