[Intraspecific variability of life strategies in boreal fishes inhabiting wide ranges].

Variability of the population structure, parameters of growth, and reproduction were analyzed in two freshwater (Siberian sturgeon and bream) and two marine (cod and flounder) widespread boreal fish species. These species have similar spectrums of adaptive life strategies including (a) the strategy of populations inhabiting zones of the species optimum, (b) the strategy of populations inhabiting the northern peripheral zones of low temperature and unstable food supply, (c) the strategy of populations inhabiting the southern peripheral zones, and (d) the strategy of dwarf forms. These spectrums of life strategies are apparently determined by (1) a high degree of intraspecific variability of the protein synthesis scale within extensive ranges of the species under study, (2) labile mechanisms regulating the plastic and generative metabolism ratio during ontogeny which are determined not only by thermal conditions but also by the level of food supply and its fluctuations, and (3) the mechanism regulating the size and weight of eggs.