Piotr Dębowski
ABSTRACT. This article presents the results of the fourth year of fishway monitoring in Włocławek Dam on the Vistula River with a Riverwatcher VAKI automatic fish counter. Technical problems in 2018 meant that the counter did not operate continuously, which resulted in gaps in data for 41% of the year mainly in winter, early spring, and fall. The year was dry and hot, and there was no typically high water in March. A total of 7,445 fish were recorded migrating upstream. Most of them were bream at 3,036 individuals followed by vimba at 2,876 individuals. Asp, sea trout, white bream, and barbel were recorded in numbers ranging from 200 to 400 individuals each. The huge decrease in the number of fish migrating in 2018 in comparison to 2017 was because of the very low water discharge during the habitual migration periods.
Key words: fish migration, fishway, fish counter, Włocławek dam, Vistula River
Przyjęto po recenzji 14.08.2019 r.