Barrier against the invasive species in the NPP Vizír

Author: Petr Hanzlík, Published: Jan. 19, 2023, 3:06 p.m.

The Vizír National Nature Monument has been facing the invasion of the common sunfish (Lepomis gibbosus), the American catfish (Ameiurus nebulosus) and the topmouth gudgeon (Pseudorasbora parva). This has a negative impact on the whole ecosystem, especially on aquatic invertebrates.

In order to prevent these species from entering the basin, we had a special device installed at the inflow to the pond. This device consists of:

  • a double row of gates
  • a 1 cm wide grating
  • a netting sleeve frame of 4 millimetres mesh and a total length of 10 metres.

The grating prevents the entry of larger objects (sticks, leaves) and animals (amphibians and larger fish). The sleeve catches the fry of invasive fish from the basin. In a tributary pond like Vizir, this device must be cleaned at least twice a week of detritus that passes through the grating and gets caught in the net. During the first cleaning, the sleeve was found to be effective in barring the entry of both Lepomis gibbosus and Pseudorasbora parva.