Variation of Digestive Enzyme Activities Depending on Season, Size and Sex of Freshwater Crayfish (Astacus leptodactylus Eschscholtz, 1823) from Lake E？irdir

This study was conducted to search the effect of sex and season on digestive enzyme activities ( protease, α-amylase, lipase) in Astacus leptodactylus species that lives in Egirdir Lake.The freshwater crayfish were caught as four seasons in a year from Egirdir Lake. The sampling was not possible for crayfish since they were not entered into trap in spring season. Therefore, the results were evaluated over three season and sex by factorial variance analysis. The results showed that sex and season affected to protease and lipase activities (p<0,05), whereas they did not affect statistically α-amylase activity in crayfish stomach (p>0.05). Results also indicated that protease enzyme activity in crayfish showed significant changes in autumn and winter while lipase enzyme activity showed changes in winter between sexs (p<0.05). However, the highest protease enzyme activity (524.73 U/mg protein) was determined in female in autumn while the highest lipase enzyme activity (0.022 U/mg protein) was observed in male in winter (p<0.05). It can be concluded that this species feed on variety of foods and has ability of digestion of these food after identification of variability of enzymes in this species