Fish book son indd

Sturgeons – contemporaries of dinosaurs
101
Such statements have had far-reaching consequences. When the numbers 
of sturgeons started to reduce drastically, and their preservation challenge 
was put forward, the following objections were voiced: ‘If sturgeons are 
primitive, do we need to save them? Their extinction is a natural evolution 
process, and they simply fail to compete with higher organized bony fi sh.”
However, academician Berg and other scientists put forth an opposite 
view derived on the basis of the comparative anatomical analysis of both 
fossils and present fi sh. According to them, the primitive characteristics of 
sturgeons had been preserved due to a fetalization; i.e. a drop-out of the fi nal 
stage of evolution and acquisition of specifi c adaptations. Thus, the observed 
similarities between sturgeons and the cartilaginous fi sh are of secondary 
nature and may be viewed as a convergence.
Sturgeons, excluding sterlets, are long-living fi sh. Their maturity time 
is not the same in diff erent basins and rivers. Sturgeons (excluding sterlets) 
do not spawn every year. Following spawning, breeders migrate down to 
the sea, grow, and again return to spawning, but this time they are larger 
in size and have more eggs. Sturgeons are normally slow-growing and late-
maturing fi sh, but in terms of weight-growth rate, sturgeons rank among the 
fastest-growing fi sh. Even if they reach their maturity later than other fi sh, 
their large sizes (excluding sterlets and shovelnose sturgeons) compensate 
for the lag in maturity.
Maturity of the large size male species (starred sturgeon, sturgeon, and 
beluga) is reached at the age between 5-13 and 8-18 years; maturity of the 
female species – at the age between 8-12 and 16-21 years. Sturgeons entering 
the Don and Dnepr Rivers are the fastest matured, while those entering the 
Volga River are the slowest matured.
Spring and summer spawning takes place in the rivers (sturgeons do not 
reproduce in seawater) with a relatively high-fl ow river current; the sturgeon 
egg is gluey and it sticks fi rmly to gravel or rock, selected by the fi sh for 
spawning. Rare instances are known when starred sturgeon and sterlet exit 
the river to spawn in the fl ood plain.
Larva of sturgeon (Starred Sturgeon)

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G.M.Palatnikov,  R.U.Qasimov
102
Breaking out of the egg, the sturgeon larvae have a yolk sac att ached to 
their belly and are fed by it (endogenous feeding) when the yolk sac is being 
going down. This is followed by external active (exogenic) feeding. Then the 
larvae either migrate directly to the areas of the sea near the river mouths 
(e.g. starred sturgeon in the Kuban River) or stay for a while in the river. But 
normally, the sturgeon fry migrate to the sea the same summer.
In the river, the sturgeon larvae fi rst feed on plankton (daphnids, etc.), 
and then - on crustaceans and worms. The beluga off spring move to predatory 
feeding while they are still in the river.
Further pre-mature fatt ening of sturgeons takes place in the sea. Thus, 
the Caspian Sea, the Sea of Azov, the Black Sea and other seas are some sort of 
large natural hatcheries for all groups of sturgeons. Breeders are also gaining 
weight in the sea between the periods of repeated spawning.
Sturgeons of the Siberian Rivers and of the Amur river permanently live 
in rivers, but by autumn they move down the river and reach the bays (Ob-
Tazov Bay, Amur estuary), deltas, and pre-estuary river areas. Their upstream 
spawning migration takes place in spring. The adult Baikal sturgeon lives in 
the Baikal Lake but migrates to rivers (Selenga, Barguzin) for spawning.
The diadromous sturgeons form the early run and the later run. The 
sturgeons, which enter the river for spawning in one particular year, stay for 
winter time the same year and then spawn in the spring of the following year, 
are referred to as the early runs. The later run sturgeons enter the river normally 
in spring and spawn in spring and in the early summer of the same year.
These are the external characteristics of sturgeons, but there is also a 
variety of likely interesting peculiarities, identifi ed in the result of modern 
embryological, physiological, biochemical, genetic and other studies.
Carl Linnaeus, the founder of modern taxonomy, att ributed the sturgeons 
to the group of Amphibians (Amphibia).
Currently, sturgeons are related to the Fish (Pisces) group. However, 
modern embryological, physiological and genetic data point at numerous 
diff erences between sturgeons and both cartilaginous fi shes and bony 
fi shes. Thus, some peculiarity is observed in the embryonic development 
of sturgeons, which is diff erent from fi sh, but similar to amphibians. There 
are peculiarities in their cerebrum structure, as well as in protein and lipid 
compositions of diff erent tissues.
It has now been demonstrated that, for a variety of factors, these fi sh 
diff er signifi cantly from both cartilaginous fi sh and bony fi sh. Moreover, for 

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Sturgeons – contemporaries of dinosaurs
103
a number of factors, their organization is superior to amphibians and is close 
not even to reptiles, but to mammals!
The sturgeons’ genetic apparatus is unique as well. As recent surveys have 
shown, sturgeons are polyploidy species. The chromosome set of diff erent 
species may be 4n (beluga, kaluga, barbel sturgeon, Persian sturgeon, starred 
sturgeon, greater shovelnose sturgeon, etc.), 8n (Russian, Siberian, Adriatic, 
lake and other sturgeons) and 16n (Sakhalin and short-nosed sturgeons). 
Moreover, the Sakhalin and short-nosed sturgeons are record-holders of the 
number of chromosomes among the vertebrate species– 500!  At the same time, 
sturgeons have no sex chromosomes, and their diff erentiation is epigamic; 
i.e., under the infl uence of environmental factors.
According to the latest data, 24 sturgeon species currently inhabit the 
water bodies of the world. Six of them live in the basin of the Caspian Sea. 
One species – beluga (Huso huso) – is related to the Beluga genus, while the 
other fi ve – to the Sturgeon genus.

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