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Abstract: River rehabilitation initiatives have become commonplace in European water courses as a result of European Union Water Framework Directive requirements. However, the short‐term responses of fishes to such work have thus far been varied, with some river rehabilitation efforts resulting in demonstrable improvements in diversity and size structure, whereas others have resulted in little or no change. Electrofishing and channel character surveys were conducted annually between 2009 and 2014 on a reach of the River Glaven (North Norfolk, UK) before and after rehabilitation work (embankment removal in 2009 and re‐meandering in 2010) as well as on a control reach immediately upstream. To assess the effects of rehabilitation work, before‐after‐control‐impact analysis tested for changes in channel character (geomorphology, substratum composition, and mesohabitat structure) and in fish species richness, relative abundance, population density, and size structure (calculated after fish data entry into the UK Environment Agency's National Fisheries Population Database). Following re‐meandering work (i.e., treatment), habitat heterogeneity and depth variation increased in the treatment reach, but fish responses were not significant except for biomass and density increases of brown trout Salmo trutta and abundance decreases of European eel Anguilla anguilla, in the treatment but not the control reach. These results are consistent with comparable river rehabilitation initiatives elsewhere, and they suggest that larger‐scale rehabilitations are probably needed to produce greater increases in fish density and diversity. It is recommended that future rehabilitation initiatives address catchment‐scale factors that can enhance ecosystem recovery, for example, removal of barriers to colonization, and increases in connectivity and water quality issues linked to eutrophication, elevated fine sediment inputs, and various pollutants. [ABSTRACT FROM AUTHOR]

The efficacy and sub-lethal consequences of single and double tagging European catfish Silurus glanis with Petersen disc and passive integrated transponder ( PIT) tags were examined in short (laboratory) and longer-term (field) experiments. Tag retention in the laboratory was 100%, with normal behaviour (i.e. feeding) in all fish returning within 36 h. In the field, 65 of 120 tagged S. glanis were recaptured from five small study ponds, with 85% retaining their PIT tags, though recapture rates and tagging efficacy were highly variable amongst locations. This is consistent with literature for other fishes, suggesting that tagging efficiency is variable across species and largely context dependent (fish length, tagging location, habitat). [ABSTRACT FROM AUTHOR]