Caspian Sea 2011
4. Pressure 4.1 Decline in bioresources
There are more than 100 species of fish in the Caspian Sea and the low deltas of adjoining riv- ers. About 40 species are fished commercially, of which six are species of sturgeon. In addition, the Caspian has sizeable resources of bony fish and tulka, mainly used for local consumption. Stur- geon are anadromous fish, living most of their long lives (ranging up to 100 years) in saline wa- ter, but migrating to fresh river water to spawn. Tulka species are marine fish which spawn and feed in the open sea and undertake some season- al migrations along sea currents. Other bony fish of the Caspian Sea mainly spawn and feed in low deltas and in the north of the sea. Sturgeon fisheries decline Six sturgeon species are found in the Caspian Sea and its drainage basin: Russian sturgeon ( Acipenser gueldenstaedtii ), Persian sturgeon ( A. persicus ), Stellate sturgeon ( A. stellatus ), Ship stur- geon ( A. nudiventris ), Sterlet ( Acipenser ruthenus ) and Beluga ( Huso huso ). The bulk of the world’s remaining stock of wild sturgeon resources is found in the Caspian, which also accounted in the past for between 80 and 90 per cent of total world caviar production.
Since 1970, pollution from various sources, mainly from industry and agriculture in surround- ing areas plus oil extraction activities, has had a major impact on the Caspian Basin and its eco- systems. Accumulations of various toxins in the main rivers surrounding the Caspian and in the sea itself have led to changes in the physiology and reproductive systems of sturgeon. In the pe- riod from 1985 to 1990, sturgeon dieoffs were recorded in the Volga and Ural rivers (Ivanov 2000). Up to 90% of sturgeon specimens exami ned showed muscle deterioration and shrinkage of the outer layers of eggs (Pavelieva et al., 1990). It is clear that the decline in recorded sturgeon catches is due to a decline in available stocks. Over a 30-year period, total sturgeon catches have declined dramatically - from 27 thousands tonnes to less than one thousand tonnes. The Great Stur- geon or Beluga ( Huso huso Linnaeus, 1758) is the biggest and most valuable sturgeon, not only in the Caspian but in the world. In the early 1990s, the total annual catch of Beluga was about one thousand tonnes: in the 2000s the catch dropped dramatically with a total in 2007 of only 33 tonnes.
Thousands of tonnes per year Total sturgeon catch in the Caspian
Illegal sturgeon catch in the Caspian
Thousands of tonnes per year
0 1 2 3 4 5 6 7
Legal catches Illegal catches
N.B.: Turkmenistan is not included
1932 1944 1956 1968 1980 1992 0 Source: Transboundary Diagnostic Analysis for the Caspian Sea, Caspian Environment Programme, 2002. Updated in 2010 with data from the United Nations Food and Agriculture organization (FAO). 2007
Source: Strukova, E. and Guchgeldiyev, Study of The Economics of Bio-resources Utilization in the Caspian, Estimation Of The Economic Value Lost From Degradation Of The Caspian Fishery, Including The Effects Of Sturgeon Poaching, 2010.
Made with FlippingBook - Online catalogs