ic life is developed in accordance with the rules of metrology, mathematical statistics and using the biocenological regularities of water objects. The basis of evaluating the stocks of water life was investigated through biocenotic conditionality in the areas of their equal probability in concentrations. The traditional method of squares in evaluating the stocks of water life was modernized with the use of probabilistic approach, the required knowledge of rules of statistical distributions of its specific concentration. Allocation of borders in the areas of probably equal concentrations of aquatic life applied in the proposed technique offer the mean integral values of probabilities. It is recommended to minimize errors of evaluation of the aquatic life resources using the statistical method of producing the average values if it is stated that casual component is more than two times higher of the regular component in a resulting error of evaluation of the average specific concentration of water life.