Towards More Effective Fish Migration: Restoring Connectivity in Freshwater Socio Ecological Systems

Rivers are fragmented by dams, weirs and sluices that restrict fish movement between important habitats. Fishways are widely used to restore river connectivity and facilitate fish movement across barriers. This thesis explores fish migration and connectivity restoration through a multiscale and multidisciplinary approach. It examines how fishways facilitate movement for entire fish communities and how connectivity is shaped by individual and successive barriers, water flows, infrastructure, management practices and wider environmental conditions. In doing so, the research moves from a small number of traditionally targeted species to entire fish communities, and from the functioning of individual fishways to patterns of movement across river networks and, ultimately, to ecological responses at the catchment scale. The findings show that effective connectivity restoration requires looking beyond individual structures and conventional target species. By integrating ecological, technical and social perspectives across spatial and temporal scales, this thesis provides a broader understanding of connectivity and how it can be more effectively restored in fragmented rivers.