Limnetica 32

Knowledge of the biological traits of native fishes distributed throughout the Maghreb, e.g., Luciobarbus callensis, the target species of this study, is essential for assessing the status of these species and for improving their conservation. In this study, the age and growth characteristics of a population in a man-made lake showing temporal variations in ecological conditions and managed for agricultural purposes were investigated. The sampled population showed a wide range of ages and an age structure dominated by middle-aged cohorts (4+ – 7+). Compared with stream populations, the studied stock was characterised by a large number of age groups. The annual growth of middle-aged fish was not great and decreased with longevity. The growth pattern was seasonal, consisting of a single growth period extending from the end of winter to spring, immediately prior to the reproductive period. Relative abundance showed slight differences between seasons. The highest values of somatic condition occurred immediately following the reproductive period. Most likely, the characteristics of the species were affected by the ecological variation of the reservoir and by the highly variable stream flowing into the reservoir. However, Luciobarbus callensis showed a high adaptability to these artificial systems.