The effects of cage culture on water quality and biological parameters of some fish populations in Karakaya dam lake

Karakaya Dam Lake is an important aquatic ecosystem, used for irrigation, fishing and recreational activity by Malatya province and the surrounding residential areas.Four sampling points were selected to determine the impact of cage aquaculture in Karakaya Dam Lake on water quality and growth and reproductive characteristics of Alburnus mossulensis, Acanthobrama marmid, Cyprinion macrostomus ve Cyprinion kais. Vertical water and fish samples were collected from the selected locations at the same time between December 2008-2009 and physico-chemical parameters of water were analyzed on a monthly basis. According to water quality values, the trophic level of Karakaya Dam Lake was determined as oligotrophic and mesotrophic.Length-weight-sex distribution, age-sex composition, the absolute-proportional growth in lenght and weight, length-weight, age-lenght, age-weight relationship, condition factor, gonadosomatic index, egg diameter and fecundity of collected fish were determined. Differences in male and female individuals according to months and sampling points with the degree of importance were determined by ANOVA and Tukey test. In addition, by the Canonical Correspoinding Analysis (CCA) used, multiple relations between environmental variables that effect ecosystem structure of dam lake and growth-reproduction parameters have been analysed and depending on the sampling points, the effect and degree of environmental factors on fish composition have beenshown.Evaluation of reproductive periods show, spawning periods of A.mossulensis, C.macrostomus and C.kais begin in May and A.marmid begins in May-June. In female subjects, distributions of species were not affected significantly by the environmental variables and ist. 1 and ist. 2 were similar.As a result, amounts of nitrogen and phosphorus in the sampling points 1 and 2 were higher than the sampling points 3 and 4 which were built after the first two and biological parameters of fish were affected accordingly.