Determination of Feeding and Growth of Hatchery-reared Brown Trout (Salmo Trutta Linnaeus, 1758) on the Eastern Black Sea Region of Turkey

In this thesis, growth and feeding of the hatchery-reared brown trout (Salmo trutta Linnaeus, 1758) were investigated to determine the success of adaptation to natural habitat on the Black Sea Region of Turkey. A total of 500 marked individuals with an average length of 4.03±0.12 cm and an average weight of 1.29±0.16 gr were released to the Çağlayan Brook of Rize province. During bimonthly sampling surveys, the length and weight of the marked and native individuals were measured, and to determine the dietary habits the stomach content of the fishes were sampled by means of gastric lavage. Some physicochemical parameters of the water were measured to determine the abiotic factors. During the sampling surveys, the measured water quality parameters were found to be suitable for brown trout. The growth in length and weight were statistically different between the months (ANOVA, p<0.05). The condition factor of both marked and native fishes was calculated and no statistical difference was determined between the groups (Kruskal-Wallis, χ2 (1) = 0.488, p = 0.48). The length-weight relationship was W= 0.0132L2.876 for marked individuals and W= 0.0109L2.946 for native individuals. Diet analysis revealed that both groups were mostly fed on plecoptera (%IRI = 35.54), diptera (%IRI = 23.91), and ephemeroptera (%IRI = 10.27). Dietary overlap was determined between the marked and native individuals as a result of NMDS analysis and no significant difference was noticed between the diet composition of the two groups as the result of ANOSIM (p>0.05). Considering the growth and feeding characteristics, it was concluded that the hatchery-reared individuals were successfully adapted to the natural habitat and developed as their conspecifics.