Monitoring of fish communities in Bolevecký pond system in 2014

Year 2014 was the ninth in which fish in Bolevecký pond system (Plzeň-Bolevec) were captured in spring using booming boat. In the last years the electrofishing was done for the purpose of so called biomanipulation, when removing of unwanted fish species should lead to increasing of water quality in this very important recreational locality. Sampling during spawning period in the last years revealed that the biomass of unwanted species decreased significantly and therefore spawning in the reed belt is limited and sampling less effective. This situation was amplified by the expansion of marophytes, which created perfect spawning substrates on the whole area of Velký Bolevecký pond and fish did not migrate to spawn to the littoral area. Declining trend in numbers of fish captured during last years has indicated that effort to eliminate fish stock of unwanted species was successful. Year 2014 was not therefore the year of massive fish removal during spawning but rather the year of fish stock monitoring after massive reduction of unwanted species and macrophytes expansion. The fish stock monitoring was, as well as in the last years, done by workers of Biology Centre AS CR, Institute of Hydrobiology together with workers of Správa veřejného statku města Plzně. Because the probability of occurrence of fish aggregations, most easily accessible for booming boat, is in the spawning period, sampling was performed in this time of the year