Some Biological Characteristics of Crayfish, Astacus leptodactylus (Decapoda; Astacidae) in Aras Dam (2008) Ali Mohsenpour Azari*, Alireza Asem, Feridun Mohebi, Saber Shiri Iranian Artemia Research Center (I.A.R.C.), Urmia, Iran   Summary: Length- Weight structure and sex ratio of Astacus leptodactylus in Aras Dam have been studied during three seasons (spring, summer and fall) in 2008. This survey has shown that %52.11 of total catch from Aras Dam was larger than the standard level of length (=100 mm) while it was %83.2 in 1997-98. As well as %27.11 of total catch was heavier than the standard level of weight (50 gr.). The total sex ratio (Male: Female) was 1: 0.70. The mean of length and weight were 106.73 20.97 mm and 40.22 30.77 gr. for males and 107.22 14.9 mm and 31.88 12.77 gr. for females respectively. High among of Standard Deviation, specially about males sample and also the decreased the total the total percentage of standard levels of length and weight suggest tat the population of Astacus leptodactylus doesn't have normal and standard conditions for harvesting and export activities. Home