Simulation of the threshold effect in efficiency of reproduction of Russian sturgeon in the Volga river

Acceptable balance between reproduction and mortality from various factors could dramatically disturbed because of the impermanence in reproductive potential, that showed a retrospective analysis of data on spawning sturgeon in the Volga. Article considers development of the model of population process with the existence of different levels of reproductive efficiency. We proposed a system of ODE, which formalizes the influence of the growth rate on mortality in juvenile period and take into account the loss of unfertilized eggs. In a computing environment was received discrete-continuous dynamical system which allowed assessing the effects of a sharp decrease in reproductive efficiency. This effect leads to the presence minimum acceptable size for the survival of Acipenser gueldenstaedtii spawning population.