Intragroup variability of growth in perch, Perca fluviatilis L., 1758 (Percidae) in waterbodies in the watershed of the Middle Ishim

Аннотация

As a result of the research carried out in 2016-2021 on the lakes of the Shchuchinsk-Borovoe resort area and on the Ishim River, material was obtained on the intragroup variability in the growth of perch. The absence of sexual variability was noted, which is explained by the relative stability and positive influence of environmental factors. The revealed generational variability of growth showed both a noticeable decrease in its rates in Lake Shchuchie and a significant increase in Lakes Borovoe, Katarkol and Tekekol. These processes of linear growth dynamics are caused by the interaction of hydrological and trophic factors. In all samples, a division of the general population into two clusters (incremental morphs) with different growth characteristics was observed. They correspond to the traditionally identified “coastal” and “pelagic” morphs of perch from the largest bodies of water (e.g. the former Aral Sea), but their differences are revealed statistically and not visually. Perch populations differ in the proportion of these clusters, which largely determines the average length per generation in general samples. Based on the characteristics of the back calculation of linear growth for clusters, all samples can be divided into two types, which in miniature resemble species-specific evolutionary r- and K-strategies (but not identical to it).