LENGTH-WEIGHT FREQUENCY AND SEX RATIO OF CRAYFISH, ASTACUS LEPTODACTYLUS, IN ARAS RESERVOIR, WEST AZERBAIJAN, IRAN

The length-weight frequency and sex ratio of crayfish (Astacus leptodactylus) in Aras Reservoir, was studied seasonally from spring 2008 to winter 2009. The total mean length and weight for the crayfish were 106. 43±7. 94mm and 35. 8±10. 86g, respectively. A measured 18. 99% of the caught crayfish exceeded the standard commercial size (120mm) and only 16. 43% of the catch weighed higher than the standard commercial weight 50 grams. The standards have been set forth by West Azerbaijan Fishery Office. Generally, the male crayfish dominated the samples. Comparisons of growth equations confirmed that the males are heavier than females with the same size. The results showed that crayfish Astacus leptodactylus has critical condition in Aras Reservoir.