Effect of toxic pollution on fish populations and mechanisms for maintaining population size

The effect of pollution on fish populations has been analyzed. It has been demonstrated that the strategy of the fish life cycle changes in the direction corresponding to r-selection. Smaller individuals that mature at an earlier age and are preadapted to energy allocation for maintaining a higher metabolic rate and activating detoxification gain a survival advantage under toxic conditions. If young females whose gametogenesis is within the normal range join the spawning stock, the population size is successfully maintained but its parameters and gene pool are changed.