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Long-term trends in the fish communities
of Lakes Peipsi and Võrtsjärv (Estonia)
Andu Kangur,* Peeter Kangur, and Ervin Pihu
Institute of Zoology and Botany at the
Estonian Agricultural University Võrtsjärv Limnological Station,
Rannu, Estonia *Corresponding author: Institute of Zoology
and Botany at the Estonian Agricultural University Võrtsjärv
Limnological Station, 61101 Rannu, Estonia; E-mail: akangur@zbi.ee
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Abstract
This study was undertaken to determine the
direction and extent of time related changes in the fish communities
of the large shallow eutrophic lakes Peipsi and Võrtsjärv The official
statistics of commercial fisheries for the periods 1931-1940 and
1950-1999 were used for trend analysis. In the ichthyocoenosis of
both lakes, several drastic and economically important changes have
occurred during recent decades. Some trends in the population dynamics
of fish (e.g., sharp decline of the stock of vendace Coregonus
albula (L.) in Lake Peipsi) are probably irreversible owing
to the eutrophication of the lake. A sharp decrease in the stock
of smelt Osmerus eperlanus (L.), caused by nighttime water
anoxia in the summer of several years, was followed by a quick recovery.
Periodic changes in the population of pike Esox lucius L.,
are related to water level fluctuations. The population dynamics
of several fishes, particularly pikeperch Stizostedion lucioperca
(L.), are, to a large extent, controlled by fishery policy, although
climatic factors are also of importance. The state of the stock
of eel Anguilla anguilla (L.), depends entirely on introduction
of young eels.
Keywords: catch statistics, population dynamics,
pikeperch, perch, pike, vendace, smelt, eel
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