USGS Home
Contact USGS
Search USGS

Search fish passage bibliography

Eberstaller, J., M. Hinterhofer and P. Parasiewicz (1998). The effectiveness of two nature-like bypass channels in an upland Austrian river. Pages 363-383 in M. Jungwirth, S. Schmutz and S. Weiss, eds. Fish Migration and Fish Bypasses, Fishing News Books, Vienna (Austria).

In Austria, the construction of fishways had come to a virtual standstill for several decades because existing facilities did not operate effectively. However, an increasing number of nature-like bypass channels have now been built. These new bypass systems resemble natural streams with regard to morphology, gradient, hydraulic conditions and substrate composition. In order to evaluate the effectiveness of these new systems, two such constructions were studied on the Mur River, in southern Austria. With the exception of adult Danube salmon Hucho hucho, all occurring fish species and their respective life- history stages were documented passing through the channels. During and just prior to their spawning season, adult European grayling Thymallus thymallus ascended these bypass channels. The number of fish caught in traps at the top of the bypasses was equal to 17% of the estimated adult populations in the 5.5 and 4.5 km-long tailwater reaches below the weirs. Periodic sampling with backpack electro fishing gear demonstrated that both channels were colonised with a fish assemblage corresponding to natural tributaries of the Mur River. Because there are no generally accepted criteria for evaluating fish passes, four criteria were established a priori to assess the efficiency of these bypass channels. Concerning upstream migration only, one bypass channel (Unzmarkt) was rated as 'effective' and another (Fisching) as 'effective to highly effective'.