Ecological Systems and Devices Annotation << Back Variability of Morpho-Biological Parameters of bream Abramis brama L. (Cyprinidae) in Water Reservoirs of the Moscow Region in the Modern Period Ryzhkova I.V. Water supply reservoirs (WSRs) in the Moscow region are important natural complexes involved in human economic cultural and educational activities. The appearance of fi sh populations in different WWTPs is different and is subject to signifi cant changes both in space and time. Detailed studies of fi sh biology in WWTPs were carried out at the early stages of succession, and currently the status of many fi sh species, including the most abundant species – bream, requires an updated assessment. The primary material was collected in the Moscow (Istrinskoe and Verkhneruzskoe water basins), Smolensk and Tver (Yauzskoe and Vazuzskoe water basins) regions; further processing of the material was carried out in the laboratory using classical ichthyological methods: biological analysis, instrumental morphometry, geometric morphometry, age and growth analysis, univariate and multivariate statistical analysis, time series analysis. Signifi cant differences in population structure parameters and morphological features are shown. In the sample of bream in the Yauzskiy gauging pond, individuals of younger age class aged 3+ prevailed, in the Vazuzskiy gauging pond fi sh aged 5+–6+ prevailed, in the Verkhneruzskiy gauging pond fi sh aged 3+, 4+ and 5+ occurred in equal proportions, in the Istrinskiy gauging pond young individuals aged 3+ prevailed. The average body length and weight, respectively, in the Yauza reservoir was 184 mm (133–355 mm), 120 g (36–753 g), for the Vazuzsky reservoir – 205 mm (108–321 mm), 169 g (24–550 g), for the Verkhneruzsky reservoir – 172 mm (112–251 mm), 94 g (25–298 g), for the Istrinsky reservoir – 143 mm (80–385 mm), 340 g (91–559 g). According to the results of the analysis of plastic features by the method of principal components, bream from the Yauza, Vazuz and Verkhneruz reservoirs are most similar to each other. The bream from the Yauzsky and Verkhneruzsky reservoirs are the most similar in terms of meristic features. Keywords: plumbing type reservoir, bream Abramis brama L., age, growth, morphometry, morphological variability. DOI: 10.25791/esip.11.2024.1489 Pp. 65-72.