Present day fauna and flora of the Caspian Sea are thought to be a combination of species from different origins: those of Caspian sea origin, others of Arctic Ocean origin, some of Atlantic and Mediterranean origin and even some of fresh water origin.

The biodiversity of the Caspian Sea is 2.5 times poorer than the biodiversity of the Black sea, and 5 times poorer than in the Barents Sea. The main reason may be the variable salinity. For fresh water fauna and flora the salinity levels of the Caspian Sea is too high, and for marine species the salinity is too low. Thus, the modern Caspian Sea is only suitable for species adapted to slightly saline waters. Despite these particular salinity conditions, the Caspian Sea is home to 87 species of microphytes and many species of green algae.

In the Caspian Sea the greatest variety is within fish and crustaceous species. These organisms, due to their very good osmoregulatory abilities, are capable of living in a very wide range of salinities ranging from fresh water up to salt concentrations even higher than those found in the ocean (Zenkevich, 1963). In the past, species with poor osmoregulation mechanisms died out because of changes in salinity. Thus, the modern biodiversity of the Caspian Sea has been 'selected' by thousands of years of de-salting and salinization processes.

The first good report about flora and fauna of the Caspian Sea was published in 1963 by L. Zinkevich. This report included a great quantity of data published in 1951 by A.Derzhavin. According to these two authors there are 718 species in the Caspian Sea: 62 species of protozoa, 397 invertebrates, 79 vertebrates and 170 species of parasitic organisms. Excluding the Protozoa and parasitic organisms, A. Derzhavin and L. Zenkevich defined 476 species of freely living Metazoa, of which 46 % are endemic to the Caspian Sea, 66 % also live in the neighboring southern seas, 4.4 % are of Atlantic and Mediterranean origin and 3% are of Arctic Ocean origin.

Furthermore, there are 315 species and sub-species of zooplankton that can be found in the Caspian sea, the majority of which are indigenous. (Kasymov, 1987) Out of the 315 species of zooplankton, 135 species are infusorians (Agamaliev, Bagirov,1975).

Due to the Caspian Sea’s division from other oceans thousands of years ago is has developed distinctive species of ichthyofauna endemic to the Caspian Sea.

The Caspian Seal (Phoca caspica), is the smallest existing varieties of seal. The Caspian seal is endemic to the region as well as being the only mammal to live in the Caspian Sea. It lives throughout the sea, occasionally going into deltas of the rivers of Volga and Ural (Badamshin, 1966, 1969). High numbers of these seals can be observed during the autumn period (October - November) on shell-composed islands in the eastern part of the Northern Caspian and on sandy spits of the Southern Caspian (Krylov, 1982, 1986). However, the largest numbers of the Caspian Seals have been observed during wintertime in icy areas of the Northern Caspian throughout the reproduction and molting seasons (Mammals of Kazakhstan, 1981). In 1993 the Caspian Seal was classified as a vulnerable specie and was included into the Red List of MUPN (International Union for Protection of Nature). The population size of the Caspian Seal has decreased approximately from 1.5 million heads by the beginning of 20-th century down to 360-400 thousand heads by the end of the eighties (Krylov, 1989).

There are many introduced species in the Volga River originating from the Caspian Sea. According to Birshtein, there are 44 species of invertebrates, including: 1 specie of Isopoda, 26 species of Amphipoda, 10 species of Cumacea, 6 species of Mysidacea, 1 specie of Decapoda and 18 species of fish which have penetrated into the Volga River from the Caspian Sea. The most commonly introduced species from the Caspian Sea into fresh water bodies are Cordylophora caspia, Polypodium hydriforme, Dreissena polymorpha, Hypania invalida, H. kovalewskyi, as well as species from the genera Theodoxus and Melanopsis. Both Cordylophora caspia and Victorella pavida have spread throughout the world and can be found living in coastal waters of Northern and Southern America, China, Australia and New Zealand.

Some species originating from the Caspian Sea have also been introduced into the Baltic Sea. For example species of goby fish as well as some water fleas (Cladocera) from the genera Cercopag. Other species such as the seahorse (Mysidae), get transported in fresh water tanks and found their way to the Baltic Sea. Cercopagis pengoi are crustaceans that have been found colonizing areas as far away as Lake Ontario.

During the 19^th Century, 'zebra mussels' (Dreissena polymorpha) were introduced into Europe and later to the Americas. These introduced species can cause ecological imbalances within the new ecosystem which may lead to further environmental problems.

The full range of flora and fauna within the Caspian Sea has still to be fully documented. The Caspian sea is believed to be home to many undiscovered species.

2.1 Species of commercial value

The natural resources of the Caspian Sea are of high economic value. Many species of species of fish, crustaceans, shrimp, as well as some aquatic birds and the Caspian seal are hunted for their commercial value.

Fish

Fisheries are very important industries throughout the Caspian countries. 500-600 thousand tons of fish are extracted annually from the Sea, the majority of which include species such as the beluga (Huso huso), sterlet (Acipenser ruthenus), as well as migrating marine herring species, zander (Stizostedion), sazan (Cyprinus carpio carpio), bream (Abramis), cat fish (Silurus glanis) and the Caspian roach (Rutilus). However, by the end of the 1950s, anthropogenic interference had lead to a severe decline in fish numbers. Large hydro-engineering constructions as well as redistribution of water for irrigation caused changes within the natural hydrological cycle. Pollution also led to the deterioration of natural habitats, without which the fish were unable to reproduce efficiently.

Some of the most commercially valuable transboundary fish species of the Caspian Sea include sturgeon (5 species) and sprat (3 species). Species of Goby are widespread throughout the Caspian Sea and form an important link in the food chain as food for predatory fishes.

Sturgeon is by far the most commercially valuable fish. It is fished for its meat as well as for caviar which is in great demand throughout the world market. As a result, the sturgeon is subjected to a lot of illegal poaching. The most commonly fished species are the Russian and Persian sturgeon (Acipenser persicus), beluga (Huso huso) and the sevruga (Acipenser stellatus). The ship (Acipenser nudiventris) fish specie population is declining, and is presently only fished in Kazakhstan. The Kura river, was previously used by as its spawning grounds however, more recently the stock has decreased and fishing in this river has lost commercial importance. In Azerbaijan and Turkmenistan the ship sturgeon is included in the Red Book. The Sterlet (Acipenser ruthenis) is a fresh water fish and lives only in the Volga River.

Up until the 1960s cod was a considerable commercial resource. However, near the end of the 1900’s the stock was radically reduced. It was not until a few years ago that the stocks began to be replenished.

Herring (or shad) is another commercially important specie. In particular the blackback shad (Alosa kessleri kessleri), dolginka shad (Alosa brashnikovi brashnikovi), Caspian shad (Alosa caspia caspia). The fishing of shad is carried out in the Volga delta (in particular of the blackback shad) as well as near Azerbaijan, Turkmenistan and along the Iranian coast.

A number of salmon species can be found in the Caspian Sea and used for commercial purposes. These species migrate to the southwestern coasts in order to feed and remain in waters of 40-50 meters in depth. However, recently the salmon population has decreased significantly due to poaching. As a result, Caspian salmon has been included into the Red Book of Kazakhstan, Turkmenistan and Russia.

The population size of the white fish, which is considered to be of commercially importance, has recently plummeted due to over-fishing. Presently it is only fished along the Volga River, even though the population continues to decrease. In the Caspian Sea, white fish are only caught for monitoring purposes. White fish is included into the Red Book of the majority of the Caspian states.

In the southern regions of the Caspian Sea, shoals of kutum (Rutilus frisii kutum) can be split into western and southern ‘herds’. In the Northern regions, kutum has become very rare, therefore Russia and Kazakhstan have included it into their Red Books.

The Asp (carp family) is another specie found in the Caspian Sea. It is a widely spread predatory specie and can be fished throughout the sea.

During the nineties, the number of sturgeon (beluga, ship and sevruga), salmon, white fish (Coregonus albula), khramulya (Varicorhinus), as well as many other species decreased due to a large amount of uncontrollable illegal fishing. Another factor effecting the number of fish was the decrease in release of young fish from artificial breeding centres.

In Turkmenistan, 2 species of crustaceous (the thick-foot and long-foot crabs) have recently been found to be an effective alternative to fish poaching as their catch volume may reach up to 50 thousand tons a year. However, present catch levels do not exceed 3-5 tons per year. At the present time these crabs are fished for in the Kara-Bogaz-Goll area.

Mammals

The only mammal to live in the Caspian Sea is the seal. Seal hunting has a long-lived history stretching back 2 to 3 centuries. It was not until the 20th century that the number of seals caught increased to hundreds of thousands of individuals. As a result, research throughout the past 10 years, has shown that the Caspian seal population has been decreasing. Between 1986 to 1995, the seal population was reduced by approximately 20%. Furthermore, in 2000, the Caspian seals suffered from an epidemic of dog distemper, which began in the Northeast and spread across the sea.

Previously, seal hunting was carried out according to a set of quotas and only during the winter months as seals can easily be seen floating on ice blocks. However, in 1997, seal hunting was declared illegal by all countries except Russia. In 1998, Russia also declared seal hunting to be illegal.

Common coastal dealing mammals include the brown hare (Lepus europaeus), wild rabbit (Oryctolagus cuniculus), coypu (Myocastor coypus), forest dormouse (Dyomys nitedula), wolf (Canis lupus), jackal (Canis aureus), fox (Vulpes vulpes), raccoon (Procyon lotor), weasel (Mustela nivalis), stone marten (Martes), badger (Meles meles), otter (lutra lutra), reed cat (Felis chaus), steppe cat (Felis libyca) and djeiran (Gasella subgutturosa). These mammals are of major economical value as well as being an important source of food for humans.

The most common ungulate along the Caspian coastline is the wild boar (Sus scrofa). These animals are subjected to sport hunting as well as being of commercial importance.

The jackal (Canis aureus) is the most widespread specie of mammal along the Caspian coast. Large numbers of jackal are to be found in the Lenkoran and Samur-Divichensky regions (Azerbaijan). They can be found mainly in lowlands and in dense thickets along river or sea banks. Jackal fur, although not of great aesthetic value, is of good commercial value particularly to the Kazakhs as they are much warmer and lighter than sheep skin.

The fox is the most commonly hunted animal for its fur. It is also a beneficial animal within the environment as it controls the rodent population. (Novikov, 1965; Gidayatov, 1967). The lynx (Felis lynx), otter, steppe cat, red cat, marten and weasel (Mustela nivalis) are also hunted for their fur. Otter fur is considered to be quite valuable. That of the red cat is of little value and can be produced only in very small quantities. Fur from the Lynx is the most valuable. However, it can only be produced in small quantities. The weasel is found throughout the Caspian region. The fur of which is not considered to be of any value. The Weasel plays a positive role within the environment by predating on rodents. The largest predator along the Caspian coast is the wolf, which spans the entire coastline.

The coypu is a valuable commercial mammal belonging to the rodent family. It is a source of meat as well as valuable fur. Its fur has dense sub-fur layer and is therefore quite water resistant which enables this animal to stay under water for long periods at a time.

The corsac fox (Vulpes corsac) and steppe cats (Felis libyca) can be found along the Caspian coastline in Kazakhstan and are also hunted for their fur and meat. Another important specie of commercial value in Kazakhstan is the saigak antelope (Saiga tatarika). Two populations of saigak exist, those belonging to Ust-Yurt population and those belonging to the Volga-Ural populations. The size of saigak population in the recent decade has been maintained at 250-275 thousand.

Birds.

Hunting of aquatic and water associated birds is a common sport throughout the Caspian states. They are hunted for their meat as well as for their feathers. Duck species are the most commonly hunted throughout the Caspian states.

The coast of Azerbaijan is an important region for migratory birds, in particular for the grey goose (Anser anser), ferruginous duck (Aythya nyroca), whistling teal (Anas crecca), grey duck (Anas superciliosa), red-wing (Turdus iliacus) and many more. Hunting is allowed throughout this region.

In Turkmenistan, the main hunting areas are along the central part of the coastline, called the Krasnovodsk gulf. 40% of the total bird poaching is thought to take place in areas surrounding the Krasnovodsk city within the gulf region.