Session A4: A Working Guide for Site Specific Evaluations of Fish Protection and Bypass Systems

Abstract: The importance of an unaffected fish migration in rivers to maintain or establish near-natural fish communities represents a scientific and a social consensus. This is underlined by European laws as the European Water Directive, demanding the ecological connectivity of rivers. In the last decades increasingly fish protection and bypass systems were developed and installed to reduce mortality at hydro power plants and water abstraction facilities. To prove their efficiency, usually a site-adapted monitoring is necessary. Until now neither German nor European standards for a recommended monitoring design are available. This leads to inconsistent methodological approaches, concerning sampling design and data analysis of individual studies. Therefore results of those studies are hard to compare. Generally links of causes and effects might be masked by methodological background noise. The German Federal Environment Agency (UBA) therefore funded a report to provide the basis for a monitoring working guide including methodological guidelines for site specific evaluation process. The working guide in its current state provides guidelines for preparation, conduction of the experiment and data analysis. Its aim is to simplify the selection of the appropriate sampling methods, sampling time and target fishes (species and development stage). 20 metrics are given as quantitative base for an evaluation of fish protection and bypass systems. Metric thresholds for a sufficient site specific ecological connectivity are not given yet, due to the lack of a sufficient database for their calibration on ecological demands. The first version of the working guide will be revised and further updated under the direction of the German Association for Water, Wastewater and Waste (DWA). The presentation of the current state aims to facilitate the discussion of the methodological approach to evaluate fish protection and bypass systems