Poster Presentation International Conference on River Connectivity (Fish Passage 2018)

Re-establishing connectivity and habitats: Considerations for fish passage in large rivers (#220)

Walter Reckendorfer 1 , Michael Jung 2 , Martin Mühlbauer 2 , Gerald Zauner 2 , Konrad Górski 3 , Martin Schletterer 4
  1. VERBUND Hydro Power GmbH, Vienna, Austria
  2. Technische Büros für Angewandte Gewässerökologie, Fischereiwirtschaft, Kulturtechnik und Wasserwirtschaft, Engelhartszell, Austria
  3. Facultad de Ciencias y CIBAS, UCSC, Concepción, Chile
  4. Department of Ecology, University of Innsbruck, Innsbruck, Austria

In order to achieve the targets of the European Water Framework Directive, it is important to think on a catchment scale, as the re-connection of river stretches might not improve ecological integrity in case suitable habitats are missing. Concerning large rivers, in some cases, re-establishment of connectivity might be only feasible using technical solutions due to limited space availability or huge reservoir water level fluctuations. We show example of fish lift in the case study Runserau. In this case suitable riverine habitats are available in the main channel or tributaries, thus re-connection is a suitable stand-alone measure by connecting free-flowing sections. On the other hand, within a chain of impoundments along a large river there is often a deficit of spawning and larvae nursery habitats for fish. Thus bypass channels that orientate on a natural side arm concerning slope, morphology and hydrology successfully feature passage, but also provide new additional type-specific habitats, that contribute to the ecological potential of the river system, as exemplified by the nature like bypass channel Ottensheim-Wilhering. These two examples show the necessity of systematic analyses to find reasonable and sustainable measures in order to manage and re-establish connectivity in rivers with multiple anthropogenic uses.