Morphological Differences between Geographically Distinct Populations of Roach (Rutilus rutilus) in Uzbekistan

Abstract

Roach (Rutilus rutilus) has established populations in irrigation reservoirs and drainage-water storage lakes across several river basins in Uzbekistan. This study evaluated meristic and morphometric variation among geographically separated populations from Lake Eastern Karateren, Shurkul Reservoir, Lake Zamonbobo, and Lake Tuzkan. During spring 2022–2025, 25 sexually mature specimens were collected from each water body. Meristic traits and classical morphometric measurements were recorded, and morphometric indices were expressed relative to standard body length or head length. Population differences were assessed using one-way ANOVA, factor analysis with principal component extraction and varimax rotation, and discriminant analysis. Across the four populations, dorsal-fin counts were II–III hard rays and 10–11 soft rays, anal-fin counts were II–III hard rays and 9–12 soft rays, and 40–44 scales were recorded in the lateral line. Most morphometric indices differed significantly among water bodies, whereas antedorsal distance and ventral–anal fin distance did not show significant differences. Five latent factors explained 68.25% of the total variance. Discriminant analysis separated the four sampled populations, with Lake Tuzkan showing the greatest distinctness in canonical discriminant space. The findings demonstrate geographical phenotypic variation in roach populations across the studied water bodies of Uzbekistan and provide a morphometric basis for population-level comparison, while further environmental and genetic evidence is required to interpret the mechanisms underlying the observed differences.