Abstract <p>Biochemical profiling of fatty acids (FAs) of pink salmon introduced into the rivers of the White and Barents seas revealed a relationship between environmental factors affecting smolts and the metabolic transformations of FAs, including conversion indices reflecting the activity of key enzymes of lipid metabolism (desaturases and elongases). The highest content of docosahexaenoic acid 22:6(n-3) up to 31% was shown for pink salmon smolts from the cold-water Voron’ya River (2.1°C), which indicated its significant role in compensatory reactions at the biomembrane level to the temperature conditions of the habitat. High values of the lipogenicity indices C16:0/C18:2n6c and C20:5n3/C18:3n3, reflecting the biosynthesis of FAs along the n-3 pathway, were established. A factor analysis of the composition of the FAs of pink salmon smolts from the studied rivers allows identification and ranking of the FAs and their groupings in pink salmon smolts. The data obtained on the FAs composition of pink salmon smolts, as well as the values of their conversion indices, pointed to the significant role of FAs in the process of growth and development of smolts. The difference in the status of their FAs is associated with the processes of their adaptation to environmental conditions, including the processes at metabolic level.</p>