Wintering pits - places of mass congregations of fish in depressions of the bottom of rivers and lakes in winter. Usually fish of one species are concentrated on the pits. In large reservoirs, wintering pits are located in the deepest places with slow currents. In lakes and reservoirs, they are located in the estuary zone of flowing rivers and streams, in places where underwater springs emerge. Mass accumulations in wintering pits are typical for sturgeon (sturgeon and sterlet) and many carp fish (carp, crucian carp, tench, bream, etc.).