ABSTRACT. In 1969 the Vistula River was dammed in Włocławek 266 km from the river mouth. This drastically reduced populations of migratory fishes in the river system. The old fishway, which functioned poorly, was modified into a vertical slot pass at the end of 2014. The results presented are from the second year of monitoring fish passage with a Riverwatcher, VAKI, automatic fish counter. A total of 7, 818 fish were recorded migrating upstream in 2016, mainly in April-May and October. Bream dominated with almost 5,000 individuals, followed by anadromous fishes – sea trout and vimba at 811 and 1123, respectively, and asp at 662. Barbel, catfish, carp, ide, perch, pikeperch, salmon, chub, grass carp, burbot, and roach were also noted. The total number of fish was almost two times higher than that in 2015. The main differences were the mass migrations of bream, more asp and barbel, and fewer sea trout. The influence impact of an auxiliary, anti-erosion dam below the main dam is discussed.
Key words: Vistula River, fish migration, fishway, fish counter
Przyjęto po recenzji 13.03.2017 r.