The aim of this study was determine the selectivity of gillnet and trammel net with different mesh sizes for C. gibelio in Eğirdir Lake. Gillnets with mesh sizes of 32, 40, 50, 60, 70, 80 and 90 mm; and trammel nets with of 100, 110, 120, 130 and 140 mm were tested for catching of C. gibelio. Fieldwork was carried out in two different station of Eğirdir Lake, in a monthly period from December 2009 to April 2010 and with a total of 10 catching trials. The SELECT method was used to determine the selectivity parameters. Number of 592 C. gibelio species were caught in the experiments which the lengths ranged between 7.3 -34.8 cm. According to the Bi-modal model which gave the lowest deviation for multifilament gillnets, the optimum lengths were determined as 8. 74, 10.92, 13.65, 16.38, 19.11, 21.84 , 32, 40, 50, 60, 70, 80, 90 mm göz açıklığındaki solungaç ağlarının optimum yakalama boyları sırasıyla 8,74, 10,92, 13,65, 16,38, 19,11, 21,84 ve 24,57 cm olarak; fanyalı ağlar için en düşük sapmayı veren Normal scale modeline göre yapılan hesaplamalar sonucunda 100, 110, 120, 130, 140 mm göz açıklığındaki fanyalı ağların optimum yakalama boyları sırasıyla 27,20, 29,92, 32,64, 35,36 ve 38,08 cm olarak bulunmuştur.
