Özet:

In 2010 in the City of Łódź, Central Poland, electrofishing was carried out at 12 sites in the Miazga, Bzura, Sokołówka and Lagiewniczanka Streams in the Vistula system. Eight fish species were recorded, of which two were alien (giebel Carassius gibelio and topmouth gudgeon Pseudorasbora parva) and only two were rheophilic (ide Leuciscus idus and gudgeon Gobio gobio). Roach Rutilus rutilus and three-spined stickleback Gasterosteus aculeatus constituted 64% of all the fish in samples. Stone loach Barbatula barbatula, usually common in other similar streams, was absent. The fish distribution and abundance was significantly determined by the stream regulation. In the Sokołówka electrofishing was conducted earlier at the same six sites in 2002. Seven species were recorded in both terms; in 2010 ide (coming from stocking) was captured instead of the previously recorded crucian carp Carassius carassius. The total fish abundance was over twice lower than in 2002.

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