Investigation of the selectivity of crayfish pinter nets through hunting studies in Tunceli Uzunçayır Dam Lake

The aim of this study was to investigate the prey selectivity of crayfish pinter nets in Tunceli Uzunçayır Dam Lake. The area where pinters were released and caught (39°01ʹ04ʺ N, 39°30ʹ07ʺ E) is the Aktuluk region of Uzunçayır Dam Lake, located in the west of Tunceli Province. During hunting, pinters were cast parallel to the shore. In the research, 100 crayfish pinters with 17 mm mesh size and single-entry double vents equipped with rhombic nets, the first of which was placed on 5 circles, the first in the form of a semicircle and the others in a round shape, were used. Pinters were repeatedly left without food and checked every 15 days between 1 June and 1 August 2024 at randomly selected stations. During the research, field studies were carried out 5 times; Temperature measurements were made at a depth of 1.5 m below the water surface. As a result of fishing, 18 male and 2 female crayfish (Pontastacus leptodactlus, Eschscholtz, 1823) were caught with pinter nets. The presence of crayfish in the lake was not reported before this study, and this study is the first report of crayfish in Uzunçayır Dam Lake.It has been observed that captured female crayfish carry eggs under their abdomens. It was determined that 6 of the 18 male crayfish were larger than the legal hunting length of 10 cm, and 12 of them were smaller than the legal hunting length. When the weight distributions were examined, it was determined that the smallest male crayfish was 18 g and the heaviest male crayfish was 93 g. As for female crayfish, the smallest crayfish was determined to be 30 g and the heaviest crayfish was 35 g. The length-weight relationship of crayfish caught with pinters was examined logarithmically using linear regression analysis as the length-age live weight relationship of individuals. When looking at R values, a strong relationship was found between length and weight in male crayfish and a very strong relationship in female crayfish. Negative allometric growth was observed in both sex groups. In this study, a total of 30 fish, including 12 Capoeta trutta, 14 Achantobrama marmid, 1 Chondrostoma regium, 2 Lusiobarbus mystaceus and 1 Cyprinion macrostomus species, were caught as bycatch living in the lake. The length-weight relationship of fish caught with Pinter nets was examined logarithmically using linear regression analysis as the length-age live weight relationship of individuals. When the R values of C. trutta and L. Mystaceus fish were examined, a strong relationship was found between their length and weight. A very weak relationship was found between length and weight in A. marmid fish. During the studies, 2 crabs were caught in crayfish pinters. As a result of the macro examination, it was determined that both crabs were male. In the studies, a male Mauremys sp., which is abundant in water systems in Eastern Anatolia. It has been determined that a freshwater turtle has been caught. The turtle was found dead by asphyxiation because it could not get out of the Pinter net. As a result of the measurements and weighing of the turtle, it was determined that it was 35 cm long and weighed 945 g.