A study was conducted to determine some ecological and. biological characters, including age, growth and reproduction in migratory population of roach, Rutilus rutilus caspicus, in Anzali wetland from early November 1999 to early December 2000. The sampling were done monthly but in the peak of spawning migration (late February to mid April) it was done weekly. Sex ratio in the population was 1 :17ei’:l&. Although the sex ratio was not significantly different even at 10% level but the sex ratio for each separate age group were significantly different at 0.5%. The correlation between total length, age, body weight, and scale radius were significant (P<0.00l). Based on the back calculation, the maximum growth rate was in ages 1 and 2. Instantaneous growth rate were the highest at ages 1 and 2. Gonadosmatic index (GSI) was age-dependent. The peaks for GSI curves were; late February and early March for the males and females. The eggs diameter varied from 0.95 mm to 1.3mm. The absolute fecundity was related to age.
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