Fish Fauna 1993
The map gives an overview of current knowledge about fish populations in Berlin bodies of water. Studies made more than 5 years ago were not used. The fishing samples in various waters occurred between 1987 and 1992 in the course of:
- preparation of a Red Data Book for fish and cyclostromata in West Berlin (Vilcinskas 1991a)
- fishing samples of bodies of water leased by the Landesverbandes Berlin e.V. im Deutschen Anglerverband (DAV e.V.) (= Berlin State Chapter of the German Fisher Association, non-profit organization) were taken in the course of operational measures (fish stock control, etc.).
- fauna study for the Naturschutz- und Grünflächenämter (= Nature Protection and Green Spaces Offices) of the Hohenschönhausen and Hellersdorf boroughs, and Berlin forests (Vilcinskas 1991b, Vilcinskas and Wolter 1992a, 1992b)
- Fischartenkartierung der Berliner Arbeitsgruppe "Wildfische" (= Fish Species Cartography of the Berlin Workgroup "Wild Fish")
- echo depth sounder studies of selected Berlin lakes (Wolter 1991).
Supplementary fish samples were necessary in order to sufficiently represent the entire area of investigation for the updating of the Fish Fauna Map.
The registration of all species of fish in a body of water requires at least 2 fishing samples a year because the activity radius of an individual species of fish in a body of water varies in the course of the year, thus affecting possibilities for detecting them. Various catching methods are employed. Electrofishing was possible in structurally diverse water sections with shelters and projections. Electrofishing, when properly used, is the most sparing method of capture because fish hardly come into contact with the capture mechanism. Mucous membranes and scales remain relatively uninjured. Fixed nets, dragline nets, and traps were used in flowing waters. Fixed nets, however, were only employed when fish were taken for residue analysis. This method of capture often injures fish and they cannot usually be returned undamaged. A combination of various capture methods is necessary in many waters in order to register the entire spectrum of species. Long-term investigations are advantageous. Species which are relatively difficult to capture, such as burbot, sheat fish, wels, and catfish, may not be detectable in a given year. Natural oscillations in population size, which are quite large among smelt and moderliesche, can be determined and the actual endangerment of this species more correctly estimated. In cases where it was not possible to conduct an adequate number of fish samplings, recreational, commercial and lease fishers were questioned, and their catch and restocking statistics were evaluated.