Compared with small rivers and streams, the study of fish communities in large rivers remains challenging as spatial and temporal data variability can be greatly influenced by sampling strategy and operator choice. In an attempt to limit this variability, a new sampling protocol for fish communities in medium‐ to large‐sized rivers was developed, based on point sampling by electric fishing and using standardised procedures and...

A pan‐European, classification of the extent of environmental degradation from chemical, physical and biological pressures on fish communities as a precursor to assess the ecological status of running waters based on fish is proposed. Twenty‐four potential pressures acting on fish communities at three different spatial scales (river basin, segment and site) were identified and class boundaries for high, good, moderate, poor an...

Fish assemblage indicators developed throughout the world were reviewed and key differences in methodologies depending on ecoregions, basins and contrasting fish fauna summarised. Common elements of existing Indices of Integrity were identified to support the development of a European‐wide fish index. These include, using reference condition, accounting for natural fish assemblage variability, evaluating metric precision and s...

The objective was to develop spatially based (type‐specific) methods to assess the ecological status of European rivers according to the EU Water Framework Directive. Some 15 000 samples from about 8000 sites were pre‐classified within a five‐tiered classification system based on hydromorphological and physico‐chemical pressures. The pre‐classification was used to identify reference conditions and to calibrate the assessment m...

After typological pre‐classification of 398 calibration sites, fish‐based metric models were used to predict the impact of human activities on river quality in European Western Highlands and Western Plains ecoregions. Calibration sites were grouped into six assemblage types and according to their geomorphology; test sites were assigned to their corresponding assemblage type. Five anthropogenic variables were used to describe t...