title: Supporting decision-making for improving longitudinal connectivity for diadromous and potamodromous fishes in complex catchments.
abstract: Preservation and restoration of Europe's endangered migratory fish species and habitats are high on the international river basin policy agenda. Improvement through restoration of longitudinal connectivity is seen as an important measure, but although prioritization of in-stream barriers has been addressed at local and regional levels the process still lacks adequate priority on the international level. This paper introduces a well-tested method, designed to help decision makers achieve the rehabilitation of targeted ichthyofauna more successfully. This method assesses artificial barriers within waters designated under the Water Framework Directive (WFD), Europe's main legislative driver for ecological improvement of river basins. The method aggregates migratory fish communities (both diadromous and potamodromous) into functional biological units (ecological fish guilds) and defines their most pressing habitat requirements. Using GIS mapping and spatial analysis of the potential ranges (fish zonation) we pin-point the most important barriers, per guild. This method was developed and deployed over a 12 year period as a practical case study, fitting data derived from the 36 regional water management organisations in the Netherlands. We delivered national advice on the prioritization of a total of 2924 barriers located within WFD water bodies, facilitating migration for all 18 indigenous migratory fish species. Scaling up to larger geographical areas can be achieved using datasets from other countries to link water body typologies to distribution ranges of migratory fish species.
authors.affiliation: Sportvisserij Nederland, Leijenseweg 115, 3721 BC Bilthoven, The Netherlands. Electronic address: breve@sportvisserijnederland.nl.
authors.forename: Niels W P
authors.initials: NWP
authors.lastname: Brevé
authors.affiliation: Deltares, Princetonlaan 6, 3584 CB Utrecht, The Netherlands.
authors.forename: Anthonie D
authors.initials: AD
authors.lastname: Buijse
authors.affiliation: Tauw bv, Australiëlaan 5, 3526 AB Utrecht, The Netherlands.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Kroes
authors.affiliation: Wanningen Water Consult, Oosterweg 127, 9751 PE Haren, The Netherlands.
authors.forename: Herman
authors.initials: H
authors.lastname: Wanningen
authors.affiliation: ATKB, Poppenbouwing 34, 4191 NZ Geldermalsen, The Netherlands.
authors.forename: Frederik T
authors.initials: FT
authors.lastname: Vriese
mesh_terms: D025041:Animal Migration; D000818:Animals; D003247:Conservation of Natural Resources / Q000379:methods*; D003661:Decision Support Techniques; D017753:Ecosystem; D005060:Europe; D005399:Fishes / Q000502:physiology*; D045483:Rivers / Q000737:chemistry
keywords: Artificial barrier; EU Water Framework Directive; Longitudinal connectivity; Migratory fish guild