Removal of the Elritze stock in Lake Sulzkar

Phyto and zooplankton densities in Lake Sulzkar were comparable to eutrophic lowland lakes in 2018. Non-local Elritzen exerted a strong feeding pressure on the zooplankton. Between 2016 and 2018, 45000 Elritzen were fished and relocated. In October 2018, it was possible to pump out the Sulzkar Sea, calcareously and eliminate the fish stock. After the water level of Lake Sulzkar was lowered by a siphon pipe in August 2018, the residual volume (max. 4 m depth) showed a significant stratification with clinograde profiles of the temperature and pH, as well as a significant increase in the ion content from 2 m depth. The oxygen profile was heterograde with a maximum of 3 m depth. Phyto and zooplankton densities in Lake Sulzkar were also comparable to eutrophic lowland lakes in 2018. Non-location Elritzen (Phoxinus phoxinus) exerted a strong feeding pressure on the zooplankton. The biomass of the phytoplankton (4 mg per litre) was more than thirty times higher than that of the zoo plankton. Between 2016 and 2018, a total of 45000 Elritzes were caught and resettled with raisins. About 20,000 animals were brought to the fish farming of the town of Zell am See for further breeding. The stocking fish in the 1970s had come from Lake Zell, where they disappeared in the 1980s. After installing the suction line, the lake could be lowered by a maximum of 3 m before the physical limit of lifting over a terrain edge was reached and the water column was demolished. In October 2018, the lake was finally drained with three dirty water pumps. After that, the approximately 500 1500 remaining in the remaining volume were killed with a total of 750 kg of burnt lime. Fishing was not possible because of the unstable mud masses.