Analysis of long-term fishing and biological data has made it possible to determine the proportion of respawning individuals (the “remainder”) in populations of Atlantic salmon Salmo salar inhabiting large rivers of the Kola Peninsula. The contribution of respawning individuals to the dynamics of the Atlantic salmon population was assessed using the mathematical simulation model. It is shown that the model population becomes more resistant to fishing with increase in the “remainder” proportion; however, the influence of such individuals on the population dynamics is noticeable only when their relative number is more than 5% in the spawning population. The results of different model experiments are interpreted. The role of respawning salmons may be determined not so much by their quantitative contribution to the reproduction process as by the maintenance of the genetic diversity of the population within the reproductive strategy characteristic of the Atlantic salmon.