L. Forró szerk.: Miscellanea Zoologica Hungarica 8. 1993 (Budapest, 1993)
Vida, A.: Expected effects of the Gabčikovo river barrage system on the ichthyofauna of the Szigetköz and its values
Qualification of the irrigation canals and the expected effects according to the number of valuable fish species are shown in Fig. 4. Mosoni-Duna The southern frontier of the Szigetköz is formed by the Mosoni-Duna. As compared to the main channel, it has a slow current, and is similar to the sidebranches. Several rivers of the Hungarian side flow into the Mosoni-Duna, such as the Rába, the Rábca and the Lajta. Its water level and faunistic assemblage are also determined by those of the other rivers. Like the side-branches, the Mosoni-Duna also had a rinsed character, so both strong currents and stagnant water bodies occurred. The fish species migrate according to the water changes, therefore the inflowing rivers are of primary importance (Rába, Rábca, Lajta). The irrigation canal system in the Szigetköz is in exclusive contacts with the Mosoni-Duna, so its fish fauna is determined by this effect as well. According to personal communications, the occurrence of the extremely rare Rutilus frisii meidingeri in the delta area can be assumed. Another species, Rutiluspigus virgo was recorded several times from the deltas of the inflowing rivers. From the stenoecious, rheophilous species of the Rába River, Zingel zingel, Z. stréber, Cobitis aurata and Gymnocephalus schraetzer occasionally are found in the Mosoni-Duna. The ichthyofauna of the Mosoni-Duna downstream the Lajta River (approximately at the level of Mosonmagyaróvár) was affected only slightly. The rivers entering the Mosoni-Duna in this area (Lajta, Rábca, Rába) can make the resettlement of the species possible. The status of the reaches upstream is more critical. The largest Gasterosteus aculeatus population within Hungary is found here, which is apparently the only significant and published one for this species. Species probably disappeared in the past few months: Pararutilus frisii meidingeri. Species expected to disappear within a few years: Chalcalburnus chalcoides mento. Species expected to suffer serious population decline: Eudontomyzon mariae, Acipenser ruthenus, Anguilla anguilla, Alburnoides bipunctatus, Barbus barbus, Chondrostoma nasus, Gobio albipinnatus, G. kessleri, Leuciscus leuciscus, Pelecus cultratus, Phoxinus phoxinus, Rutilus pigus virgo, Vimba vimba, Silurus glanis, Lota lota, Gymnocephalus schraetzer, Zingel zingel, Z. stréber. Species expected to be indifferent as regards to these changes: Esox lucius, Cyprinus carpio, C. carpio m. hungaricus, Abramis ballerus, A. brama, A. sapa, Alburnus alburnus, Aspius aspius, Blicca bjoerkna, Carassius carassius, C. auratus, Ctenopharyngodon idella, Gobio gobio, Hypophthalmichthys molitrix, H. nobilis, Leuciscus cephalus, L. idus, Pseudorasbora parva, Rhodeus sericeus amarus, Rutilus rutilus, Scardinius erythrophthalmus, Tinea tinea, Cobitis taenia, C. aurata, Misgurnus fossilis, Noemacheilus barbatulus, Lepomis gibbosus, Gasterosteus aculeatus, Perca fluviatilis, Gymnocephalus cernuus, Stizostedion lucioperca, S. volgense, Proterorhinus marmoratus. Qualification of the Mosoni-Duna and the expected effects according to the number of valuable fish species are given in Fig. 5.
