Population dynamics of freshwater crayfish (Astacus leptodactylus) in Aras reservoir, Iran

Aras dam is one of the important water reservoirs in iran with a total areaof nearly15000 ha. population dynamics including length and weightcomposition, fecundity, sex ratio, molting time, and reproduction and capturetimes of freshwater crayfish (astacus leptodactylus) of aras reservoir wasinvestigated during 2012-2013. the results revealed that the mean totallength and weight of captured crayfish were 106.26 ± 12.89mm and 38.79 ±15.54g, respectively. the largest crayfish had 171mm length and 216gweight. mean number of ovarian and pleopodal eggs were 286 ± 82 and246.31± 80.4, respectively (p≤ 0.05). in this study, male to female ratio wasobtained as 1.21: 1. the male molting at 16 º c was started from late apriland ended in late may, when the water temperature reached 18 º c. thesecond molting of males and the first molting of females occurredsimultaneously at 18 º c water temperature in september. matting of astacusleptodactylus was started from november and continued until may.harvesting period was from may to late november. the results showed thatthe number of eggs were variable (from 200 to 400 eggs) and depended onspawner size, environmental condition and available food. besides, crayfishwith higher lengths and weights had increased fecundity with a directpositive correlation. a ban on fishing during the reproduction season, use ofappropriate nets and proper management should be performed to preserve thestocks of this species.