Abstract <p>Data are presented on changes in the Caspian Sea water level over the last 180 years. During the regression phase, the sea area decreases sharply, while salinity increases, especially in the shallow northern part of the basin. One of the primary drivers of sea-level decline is the reduced discharge of its tributary rivers. Changes in seawater salinity have led to a restructuring of phytoplankton, zooplankton, and benthic communities. As a result, the development of freshwater and brackish‑water species has declined, while the abundance of marine species has increased. This restructuring of planktonic and benthic communities has reduced their total biomass, so the overall sea productivity has decreased. This, in turn, has resulted in deterioration of fish resources, and fish populations have fallen into a depressed state. However, with the onset of transgressive phases, the species composition of plankton and benthos communities should recover; their abundance and biomass can increase sharply, and the biological productivity of the sea may return nearly to its initial level. Sustaining fish stocks requires artificial replenishment of populations with juvenile fish. To achieve this, it is proposed to expand marine fishing in feeding areas while gradually reducing both the zone and intensity of riverine fishing in spawning areas.</p>