Impact of the development and three decades operation of the “Lake Tisza” reservoir on the fish community of this area

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Article Title: Impact of the development and three decades operation of the “Lake Tisza” reservoir on the fish community of this area
Authors: Harka A., Csipkés R., Kovács P., Lajos J.
Affiliation: Hungarian Ichthyological Society, Tiszafüred
BioAqua Pro Ltd., Debrecen
Middle-Tisza District Environment and Water Directorate, Szolnok University of Debrecen, Centre for Agricultural Sciences and Engineering, Debrecen
Abstract: The Lake Tisza is a reservoir with an area of 127 square km, created by damming of River Tisza. The reservoir has two major areas: the river bed of the Tisza and the reservoir filled in 1978. In this area 55 fish species have been identified since 1970. Because of the damming the rheophilic species (Acipenser ruthenus, Barbus barbus) quickly left the area but the populations of eurytopic and stagnophilic species have started to grow. Some populations’ growth was slow and balanced (Tinca tinca), some was quick and exponential (Abramis brama). The changes in the population dynamics were more intense than what the new ecological conditions could explain. Positive amplitude could be seen in the population size of Abramis brama and Esox lucius, negative in Blicca bjoerkna and Abramis sapa. But the extreme changes in the population sizes were followed by a reverse process. The phytophilic fish species found very good spawning areas and enough to feed in a few years after the first flooding of the reservoir. As a result, the catch increased. After a few years the terrestrial vegetation disappeared and the amount of aquatic weeds increased. Because of these effects and the continuous sedimentation the fish production decreased. Nowadays human interventions are needed to slow down the succession of the artificial ecosystem.
Keywords: damming, relative abundance, guilds, catch, invasive species
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*Correspondence: Csipkés R., BioAqua Pro Ltd., 4032 Debrecen, Békessy Béla u. 8., Hungary. Tel. +36-70-772-0542, e-mail: sziafu@gmail.com