How did the decline in Caspian Sea water levels affect sturgeon spawning grounds?

The decline in Caspian Sea water levels, which has been observed since 1930, is primarily linked to climatic changes and human activities such as the construction of dams and reservoirs on inflowing rivers like the Volga.12

These environmental changes have significantly impacted sturgeon populations in the following ways:

• Blocked Access: The system of dams and reservoirs has severely curtailed or blocked access to the natural spawning grounds in the Volga and other rivers for anadromous species, such as the beluga sturgeon.1
• Habitat Alteration: The reduction in river discharge and the alteration of flow regimes have fundamentally changed the habitats necessary for these fish to reproduce.1
• Artificial Breeding: Due to the deterioration of natural spawning grounds and the decline of fisheries, a significant portion of Caspian sturgeon—estimated at three-fifths—are now bred artificially rather than in their natural environments.1

These factors, combined with water pollution and overfishing, have placed many sturgeon species at risk of extinction.31