Comparison of Morphological Variations and Some Biological Features of Brown Trout Salmo trutta farioResident in Chesli and Khorma Rivers in Guilan

The morphological variations and sexual dimorphism of brown trout Salmo trutta morpha fario residual were studied in two rivers, Chesli and Khorma, in western and eastern of Guilan province using 39 morphometric and 13 meristic characteristics. Univariate analysis of variance (One-way ANOVA) revealed significant differences of varying degrees between the means of the two samples for 25 standardized morphometric measurements and six meristic counts, showing relatively high phenotypic variations between the two populations. No significant differences were observed between males and females, indicating that no sexual dimorphism exists in the studied fish. Plotting of discriminant functions, 1 and 2, for morphometric and meristic characteristics revealed completely obvious separation with 100% divergence between the species of the two areas. Only in Chesli River some differences were observed between males and females according to the meristic’ second function, while there were no morphological differences between males and females in Khorma River. On the average, the correctness of assignment of individuals into their original populations based on their morphometric and meristic characteristics was 87.4% and 70.1 %, respectively.