Fish book son indd

G.M.Palatnikov,  R.U.Qasimov
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was formed in place of the eastern part of the Tethys Sea, with its species partly 
extinct and partly adapted to the freshwater.  The Sarmatian Sea existed for 
2-5 million years, and exactly within this time frame the fresh water fl ora and 
fauna formed, the remains of which have been preserved to the present day.
About 10 million years ago, the area of the sea gradually evolved, and 
its salinity increased signifi cantly. Its inhabitants changed too; some of them 
adapted to the new salinity, some became extinct, and others moved closer 
to the rivers.
8 million years ago, the Pontic Sea formed, which included the modern 
Black and Caspian Seas. Modern Caucasus and Crimean mountains were 
shaped in the form of islands. The Pontic Sea was almost a freshwater reservoir 
(its salinity was less than the current salinity of the Caspian Sea).
One million years ago a further land elevation occurred, which fi nally 
separated the Black and Caspian Seas; with the Caspian maintaining 
freshwater peculiarity of the Pontic Sea.
The eastern part of the Mediterranean, Black and Caspian Seas, the 
Persian Gulf, as well as the sea of the Malay Archipelago - are all the remnants 
of the Tethys Sea. But the Caspian turned out to be cut off  the World’s ocean. 
Therefore, the salinity of the Caspian Sea can most likely be explained by the 
fact that it was originated from the ancient Tethys Sea.
At present, the Caspian is conditionally divided into three parts: Northern, 
Central, and Southern. The boundary between Northern and Central parts runs 
through Cheleken Island (near the river Terek estuary) and Cape Tiub-Karagan 
(port of Shevchenko). The boundary between the Central and Southern parts 
runs from the Absheron Peninsula, which connects Zhiloy Island on the west 
with Cape Kuuli on the east (to the north of Turkmenbashi city).
The Northern sector of the Caspian Sea occupies approximately 25% 
of the total area, while the Central and Southern – 37% each. However, the 
Northern Caspian accounts for only 0.5% of the total water volume, the Central 
Caspian – 33.9%, and the Southern Caspian – 65.6%. These numbers refl ect 
the  fl uctuations of the Caspian Sea depths. The Northern Caspian is very 
shallow, with an average depth of less than 5 meters. The main peculiarity 
of the Central Caspian is the Derbent depression, with a depth of more than 
500 m. The Southern Caspian includes the South Caspian depression, with its 
deepest point of 1,025 m below sea level.
The Caspian Sea is full of mysteries and legends. One of the main mysteries 
is the fl uctuation of the sea level. The mysterious behavior of this unique 

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Sturgeons – contemporaries of dinosaurs
95
water reservoir att racted many famous scientists. The German naturalist and 
traveler Alexander Humboldt, who travelled through Russia to the Urals, the 
Altai and the Caspian Sea in 1829, put forward a hypothesis that the sea  level 
fl uctuation occurred due to a patt ern of regular repetition cycles of excessively 
arid and excessively humid periods. His countryman Peter Simon Pallas, who 
headed the expedition of the Petersburg Academy of Sciences to the central 
regions of Russia, the areas of Lower Volga region and the Caspian Sea lowland 
in 1768-1774, indicated that the sea level fl uctuations depended on hydro-
meteorological factors, such as temperature, wind, atmospheric precipitations, 
and the quantity of water brought in by rivers. Some fantastic hypotheses 
were also brought forward, such as “There is a hole in the Kara-Bogaz-Gol 
gulf through which the waters of the Caspian drain into the ocean.”
The Caspian Sea level rise resulted in the change of physical and 
geographical conditions, which led to the downfall of the Khazar Khaganate 
and extinction of the Khazars, as the economy of the country had collapsed 
due to the loss of two-thirds of its territory. Lev Gumilev, a Russian historian, 
ethnologist and anthropologist, describes the downfall of the Khazar 
Khaganate in a following dramatic tone: “The combined att ack of Russians, 
Oghuz Turks and Pechenegs against the Khazars in 965 brought an end to the 
independence of the semi-fl ooded nation.”
The shape of the Caspian Sea constantly changes. The sea level had risen 
to an absolute elevation of 49 m and fallen to 50 m. At its highest sea level, a 
link was formed between the Caspian and the Black Sea via the Kumo-Manich 
depression. The unstable level of the Caspian Sea is evidenced by a number 
of archaeological excavations. For example, skeletons of Scythian soldiers 
buried in tombs in the 1
st
 century B.C. were found during the construction of 
a dam beneath the bott om of Apsheron Bay.
According to the Italian geographer Marino Sanuto (1320), “The sea rose 
by several inches a year and fl ooded a number of good cities”. The Caspian has 
recently experienced sharp rises and falls of the sea level as well. According 
to the Russian historian Vassily Tatishchev (1793), “in 1742, the sea level had 
rose by more than 8 feet since 1723”; i.e., 2.5 m over 19 years. According to 
academician L.S. Berg, the sea level fell by more than 2 m over the period 
between 1807 and 1824.
In the 1930s, the sea level started falling once again. In 1977, the lowest 
level for the last 300 years was recorded: -29.03 m. Since 1978, the level of the 
Caspian Sea has begin to rise; at present, it is at -27 m and, and the sea level 
continues to rise.

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G.M.Palatnikov,  R.U.Qasimov
96
The Caspian Sea level may increase by another 4-5 m compared to today’s 
level due to climatic conditions. The sea water is likely to move inland by 
tens of kilometers. Currently, there is no consensus as to the reasons of the 
Caspian Sea level fl uctuations
About 13 million years ago, the ancestors of the Caspian sturgeons 
inhabited the Sarmatian Sea along with tunas, mullets, dolphins and whales. 
There were only two sturgeon species, while the third species inhabited the 
rivers. However, over the past years the Caucasus Mountains formed, the 
lakes and the Mediterranean Sea turned into saline deserts, and the Akchagil 
Sea was located at the Ural Mountains. Glaciers were on the same latitude 
as the cities of Volgograd and Rostov-on-Don. The link between the Caspian 
and Pontic Seas was broken approximately 14 million years ago; the Aral 
Lake became isolated in the 13
th
 century.  Since then, each water basin had 
formed its own peculiarities. 
The Caspian Sea was isolated from the World Ocean, resulting in the 
formation of its unique biocenosis. That is why the majority of the Caspian 
species are endemics. The Caspian biota can be divided into four groups.
The fi rst group includes the descendants of ancient species that inhabited 
the Tethis Sea about 70 million years ago. These forms include the Caspian 
gobies and shads, some mollusks and most of the crustaceans. Of local 
crustaceans, the long-clawed crayfi sh (Artemia) are abundant in the Caspian 
Sea.
The second group of the Caspian fauna is comprised of the Arctic species 
that entered the Caspian from the north during the post-glacial period. Of 
invertebrates, this group includes mysids – small (5 to 2.5 mm) crustaceans 
that resemble shrimps, and tiny sea cockroaches belonging to the order of 
Isopoda (isopods).
Fish in this group include the Caspian brown trout and inconnu – the 
sole representative of the Cisco family in the Caspian. Nelma, the fi sh very 
close to inconnu, lives in the northern seas of Eurasia and America. Inconnu, 
the valuable commercial fi sh (130 cm, 14 kg) feeds on kilkas and off spring of 
other herrings. When spawning, inconnu swims upstream the Volga River, 
up to the Kama river.
The Arctic species also include the only marine mammal in the Caspian 
– the Caspian seal (Caspian phoca) from the seal family. Caspian seals live 
in herds and feed on small fi sh and crustaceans. The “northern” habits of 
seals become apparent during breeding. The white pups are born in winter 

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