Population dynamics of growth of young sockeye salmon in Lake Dalnee

Three periods sharply differing in the state of the ecosystem were observed in Lake Dalnee over the period of 30 years. 1. Different abundance of sockeye salmon, three-spined stickleback and predacious char; 2. Appearance and disappearance of a four-year periodicity in the abundance fluctuations; 3. Different proportions of one-, two- and three-year old fish migrating to sea and the number of residuals; (Changes in the first and second trophic levels and in biogenic content in the water took place. These features are associated with long-lasting changes. Disturbances in one link of the ecosystem resulted in serious long-term changes in the whole system. Such change of dynamic equilibrium may become irreversible.Read at the Limnological Congress in Leningrad, 1971.