Sturgeon biodiversity and conservation

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Figure 4. Estimated numbers of sturgeons in the Northern Caspian Sea from the Volga and Ural river populations.
river than they do now. These changes resulted in
decreases in natural reproduction in the Volga River
and in changes in the population structure of this
species.
In response to this decline in natural reproduction,
the Soviet government began a program in the
early 1960s to enhance sturgeons through artificial
propagation (Barannikova 1995). Throughout the
1960s, more than 3.9 million beluga juveniles were
released from hatcheries annually. In the 1970s, the
annual release reached more than 12.9 million
young, and by the early 1980s, the average number
of the young belugas released into the Volga River
was 19.4 million (Figure 3). At present, practically
all beluga (96.3%) in the Volga River consist of
hatchery propagated fish (Khodorevskaya 1986,
1992). However, artificial propagation does not
completely compensate for the loss of natural reproduction
of beluga in the Volga River. The population
of beluga continues to decline even though
the number of beluga harvested does not exceed
0.1% of the number of individuals released.
Spawning sites for beluga in the Ural River remain
intact and the Ural River stock of beluga is
replenished by natural reproduction. Until the late
1970s, the number and biomass of beluga migrating
into the Ural River was considerably smaller than
that migrating into the Volga River (Figure 4).