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The majority of these species are migratory, semi-migratory and fluvial fish that are caught in the region of the Volga mouth (and to a lesser extent the Ural) where water chemistry and food resources favor their growth. However, regulation of the Volga flows following the construction of the Volgograd cascade in the 1960s apparently resulted in serious changes to their spawning, living habitat, and productivity. A fall in sea level during the period 1971-1978 probably further affected the life cycle of these fish species that rely on the high primary and secondary biological productivity of the northern shelf of the Caspian. Catches of these bony fishes fell to 55 percent of the pre-1960 levels and never recovered. The recorded catch since 1990 does not reflect total catch, which must take into consideration apparent substantial poaching and unrecorded fisheries.
Catches of salmon increased between 1932 and 1960, but since then have fallen to very low levels. This species is on the verge of extinction and efforts are being made to save it. Catches of large and small ordinary fishes, the backbone of fishing for local consumption, have declined significantly for reasons not yet fully understood. The reported decline may be due to unrecorded catch and large subsistence fishing by the local population, but there are environmental factors affecting the state of these stocks. It is estimated that between 30% and 45% of juveniles hatched in the Volga do not reach commercial size due to pollution alone. Natural mortality, illegal fishing, etc., also have adverse impact on the stocks.
Catches of herring and mullet increased during the early period, peaking in the late 1950s and declining to a fraction of the potential. There is a large unexploited stock of herring and mullet (in fact in the Caspian, only Iran has a sizeable mullet catch), since the introduction of a ban on fishing with nets in the Caspian. The ban was meant to protect immature sturgeon, but it has aided herring and mullet because netting is the only fishing technique that catches them.
The sprat catch increased dramatically with the introduction of light attraction and fish pumps in the early 1960s. A proportion of the catch was reduced to fishmeal; however, a significant volume was frozen or otherwise processed for human consumption. The overall catch of kilka in the countries other than Iran shows a declining trend since the 1990s due to an obsolete and unseaworthy fleet. Until 1999, the kilka catch in Iran showed a steadily growing trend following the national plans to optimize use of this resource. However, in recent times catches in both Russia and Iran have dropped: From January to November 2001, the Russian Federation catch amounted to only 30,000 tonnes and in 2000 and 2001 the Iranian kilka catch declined each year by 30-35%; a total of 50% recorded since 1999. One of the possible threats to the state of kilka stocks may be the recent accidental introduction of Mnemiopsis to the Caspian Sea.
Source: Transboundary Diagnostic Analysis (TDA)
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