Ichtiofauna sytrumieni w systemie Neru w mieście Łodzi

Abstract

In 2010 in the City of Łódź, Central Poland, electrofishing was carried out at 15 sites in the Dobrzynka, Jasień, Olechówka, Łódka and Jasieniec Streams in the Ner/Odra system. Fourteen fish species were recorded (13 species in the Olechówka and altogether 7 species in the remaining streams), of which six were limnophilic and only two rheophilic. Sunbleak Leucaspius delineatus, gudgeon Gobio gobio and stoneloach Barbatula barbatula constituted 90% of all the fish in samples. Over 100 specimens were caught at each site in the Olechówka Stream, while only 1 -11 specimens were recorded at each of the remaining sites (except one fishless site in the Jasieniec Stream). The fish distribution was determined by water purity strongly connected with the type (combined/separate) of urban sewage system functioning in a given stream basin. The condition of ichthyofauna in 2010 was slightly better than during electrofishing conducted in 2001. The Jasień and Łódka Streams were fishless in 2001 while in 2010 several fish specimens at each site belonging to the total of 3 and 4 species, respectively were recorded. In the Olechówka, in 2010 five new species were caught and the total fish abundance was over 3 times higher than in 2001.