Survey on some biological characteristics of Caspian Roach(Rutilus rutilus caspicus) in coastal waters of Golestan Province

This study was conducted on coastal waters of Golestan province in 2004. The relationship between body weight–fork length and Age–fork length for all samples were obtained: W= 1.5 × 10-3 FL 2.1200, (r = 0.8210) and FL = 139.630, Age0.3372, (r = 0.8313).In this research growth formula and its parameters was estimated: Lt = 33.48[1-exp-0.250 (t + 0.378)], L = 33.48cm, k = 0.250, to = -0.378.The average of condition factor for male and female were obtained 1.256±0.2640 and 1.033±0.2456, respectively. Samples were at 7 different age classes (2-8 years) and the most fish numbers (51.30%) which involved were 3 and 4 years old. 77.45% of samples were female and 22.54% of them were male so sexual–ratio was obtained: 1:3.53 (male:female). GSI peak for female at first of forth week in April was (21.8345) and male at the end of third week in March was (8.2720). The Minimum, maximum and mean of absolute fecundity were estimated: 4239, 85187, 20891 ova, respectively.