Population Growth and Age Structure of the Pikeperch Sander Lucioperca (Percidae) from Lake Necheritsa (Sebezhsky National Park, Pskov Oblast, Sebezhsky District)статья
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Аннотация:The size, age, and sex structures of pikeperch Sander (L.) from Lake Necheritsa (SebezhskyNational Park) have been studied, as has the linear growth using back-calculation according to the Leo directdependence function. The growth of pikeperch is described formally by linear equation L(t) = 5.4x + 0.2 (cm). Thelength frequencies of individual age groups are normally distributed, which corresponds to ideas about linearfish growth. The population is represented by 13 age classes; the maximum length of an individual in the sampleis 872 cm. The analysis of the diet showed the presence of 6 mass fish species observed in the catch,including the young pikeperch; the ratios of individual species in the diet and the sample indicates an absenceof electivity of nutrition. According to the estimates, the proportion of pikeperch in the ichthyocenosis in theperiod 1989–2022 in Lake Necheritsa has increased ∼8 times. A comparative analysis of the linear growth ofpikeperch from populations of different regions under environmental conditions, differing in a number of valuesof key parameters, is carried out. Growth rates of pikeperch from southern populations are generallyhigher and more consistent with asymptotic growth, while the size limits and life expectancy are generallyhigher in northern populations. A hypothesis has been tested about the causes of differences in the nature oflinear growth.
