The effect of light on the pleopodal egg production of freshwater crayfish, Astacus leptodactylus Eschscholtz

In the present study, the effect of light on the pleopodal egg production of freshwater crayfish, A. leptodactylus was investigated.For this aim, crayfish were stocked into three different light regimes (natural daily light, 24 hours dark and 8 hours light-16 hours dark) with three replicates. For this study, 36 males and 144 females of A. leptodactylus were used.At the end of the study the best result was obtained from the crayfish exposed to 24 hours dark. The number of females produced pleopodal eggs were significantly higher in the females exposed to 24 hours dark than the females exposed to natural daily light (P<0.01). The females exposed to 8 hours light 16 hours dark had more pleopodal eggs than the females exposed to natural daily light. On the other hand, it was found that there was not a significant difference in the number of pleopodal egg carrying females between the crayfish exposed to 8 hours light-16 hours dark and the crayfish exposed to 24 hours dark, and the crayfish exposed to natural daily light (P>0.05).In conclusion, this study showed that light doesn?t have an effect on the time of mating and pleopodal egg laying time of A. leptodactylus, but an increase in darkness causes a significant increase (P<0.01) in the rate of mating and number of pleopodal egg carrying females.Key Words: Freshwater crayfish, Astacus leptodactylus, light, pleopodal eggs, production