Some biological characteristics of roach, Rutilus rutilus caspicus, in Gomishan wetland

This study was conducted to determine some biological characteristics of migration population of roach, rutilus caspius including age, growth and reproduction in Gomishan wetland from early November 1999 to early December 2000. The sampling were carried out monthly but in the peak of spawning period (late February to mid April) it was done weekly. The sex ratio was found M:F=1.17:1.00 without any significant difference (even at 10% level); but the results of the sex ratio for each separate age group showed significant difference (p< 0.05). A significant correlation was determined between total lengths, body weight, scale radius and age Based on back calculation, the maximum growth rate were found in ages 1+ and 2+ Gonadosmatic index (GSl) was age-dependent; with two peaks or late February and early March for males und late March and early April for females. The eggs diameter was measured with a range from 0.9 mm to 1.45 mm and the absolute fecundity was related to age......