The present study was carried out to evaluate the effects of selectivity of fyke-nets of different mesh size on Astacus leptodactylus (Eschscholtz, 1823), in lake Egirdir in Turkey. Crayfish were sampled monthly using fyke-nets of 26 mm (control), 34 mm (traditional), and 42 mm (increased) mesh size from July to December 2007. Differences in the mean size, weight, and number of crayfish caught with each mesh size were determined. The average length and weight were found to increase proportionally to mesh size. The highest mean weight (g) (+/- SD) (41.07 +/- 4.61) was achieved at 42 mm mesh size compared with mean weights of 32.76 +/- 4.53 and 29.29 +/- 4.37 at sizes of 34 and 26 mm, respectively. The same trend was observed in mean TL of crayfish caught at 42, 34, and 26 mm size, but no significant difference was detected in mean length and weight for male and female crayfish. The weight of crayfish caught in 42 mm mesh was 8.3% higher than that in 34 mm mesh size. The lowest number of crayfish was caught with the 42 mm mesh size, while the highest number was captured with 34 mm mesh.