Towards a method for determining the age of chum salmon

The purpose of the work is to perform a quantitative comparative analysis of the structure and size of annual rings of chum salmon scales to prepare a methodological manual for determining age. The research material included scale preparations from 493 chum salmon producers of different ages, on which sclerites were counted and the diameter of annual rings was measured. Methods used : comparative data analysis, descriptive statistics methods. Results: it was found that the size of the scales, the size of each of the annual rings, as well as the number of sclerites in the annual rings of male and female chum salmon within each age group do not differ. The number of sclerites forming each annual ring, as well as the radius of the rings, varies significantly among different individuals. With age, as the length and mass of fish increase, the size of the scales naturally increases. Moreover, an acceleration in the growth rate is observed during the year preceding puberty. As a result, the number of sclerites in the last annual ring, as well as the size of this ring in fish that reach sexual maturity is always greater than in fish of the same age, but remaining in the sea to continue feeding. Practical significance: the presented article is a scientific accompaniment of a methodological manual for the practical determination of the age of chum salmon by scales.