Species and habitats
Principal habitats for fish species
For a fish to complete its life cycle it must move through 3 different habitats: spawning habitat, pasturing habitat and wintering habitat. For fish species with limited migration range these three habitats coincide.
Semi-migrating fish species may find pasture habitats out at sea, but during the wintering and spawning seasons they move to rivers. Some marine fish carry out considerable migrations within the seawater area, while others may inhabit relatively limited areas of the sea. The majority of the Caspian fish species inhabit the coastal zone of the sea at depths ranging between 50 – 70 m.
Semi-migrating fish species:
These fish spawn in the deltas and downstream reaches of rivers and use the fresh water deltas as pasture habitats. The optimal levels of salinity for most of the commercial fish is approximately 8g/l. During years of high water levels, optimal saline waters cover all of the northern Caspian as well as coastal areas adjacent to the river mouths within the Middle Caspian zone.
Migrating fish species:
Sturgeon – the most valuable commercial fish - spawn in the rivers of the Caspian basin. These fish migrate upstream from the river basins for hundreds of kilometers. Sturgeons select areas with pebbly or hard sandy ground as spawning grounds. However, the construction of dams have been restricted fish monement to the lower reaches of the rivers prevent the sturgeon from migrating up the rivers to spawn and has led to a decrease in the natural reproduction. Previously, 53 spawning grounds existed in Kura and 290 in Araks, however only 5 in-channel spawning grounds remain in this nine system with an area of 112.8 hectares (Voinova, Alekperov, 1992).
Marine fish species:
Commercial marine fish of live throughout the Caspian Sea. Different geographical regions within the sea play specific roles: the shallow northern regions are important for reproduction as well as for development at early stages of life. Typical fish found to reproduce in the northern Caspian region include the Dolginka herring (Alosa brashnikovi brashnikovi), the big eye shad (Alosa saposhnikovi) as well as the ordinary sprat (Clupeonella delicatula caspia). The Middle and Southern Caspian regions are feeding and fattening areas. The Caspian marine species do not have any clearly expressed wintering period. This can be attributed to the consistent climatic conditions year round which leads to ongoing development of fodder organisms. These fodder organisms act as a continual food source for the fish.
Principle habitats for bird species
The Caspian Sea is situated on major migratory routes for many bird species (Dolgushin, 1960-1974; Belik, 1996; Birds of USSR, 1987, 1988; Fauna of USSR. Birds, 1961, 1962; Birds of the Soviet Union, 1952), and it is therefore of important value for the whole of Eurasia. The majority of migratory birds stem from the Siberian-Asian region. In the autumn the birds concentrate on the northeast and northern coasts of the Caspian. Gradually, they begin moving along the western coast towards the south. At this point different species may take different routes; some continue moving south along the western coast others migrate further west along the Caucasian mountain range. The birds originating from the central and northwestern districts of Russia migrate to the seacoast along the Volga. In the delta area of the Volga this stream of migrant birds merges with those from Asia. The Ural and Emba rivers are also important migratory paths. During spring, the migration routes move back in the opposite direction.
Principle habitats for mammals
The only sea mammal living in the Caspian Sea is the seal. In the winter the seals concentrate in the Northern Caspian, near edges of ice packs, where they carry out their whelping, and molting. A small proportion of seals remain on islands near the coast of Turkmenistan throughout the winter. In the summer the seals migrate to the Middle and Southern Caspian in order to fatten up. However, a few do remain in the Northern Caspian.
The coastal mammals live mainly throughout coastal strips in bushes and reed thickets. Typical mammals to be found in these habitats include wild boar, otter, European mink, striped raccoon and muskrat. Many species of rodents and hares may inhabit coastal areas characterized by steppe and semi desert environments. Species such as the saigak antelope (Saiga tatarica) as well as the djeiran (Gasella subgutturosa) can be found within the desert and semi-desert ecosystems along the coastal regions. Three herds of saigak (Saiga tatarica) live in the northern near-Caspian zone: the Ustiyur herd (between the Caspian and Aral Sea), Guriev herd (area between the Volga and Ural Rivers) and the Kalmyk heard. Since the prohibition of saigak hunting (1991) their number has increased to 300 thousand. Saigaks are migratory and may migrate as far as 300-500km. However, in recent years no considerable migration has been observed. Most of the saigak stock stay within the southern regions of Astrakhan. Recent migrations to the coast during wintertime was observed only in saigak herds living between the Volga and Ural Rivers.