ABSTRACT
Vertical slot fish passes are considered as an efficient solution to accommodate multiple fish species, with a compact design. Limited data is available on the ability of fish with poor swimming capacity to cross such fish passes. This paper investigates the possible benefit of setting macro bed roughness elements on the pools’ floors. Different configurations were tested in a model at scale 1:5. This model had been previously used with success for tests with living material. Two benthic fish species were used: Stone Loach (Barbatula barbatula) and Bullhead (Cottus gobio). Macro bed roughness elements improved their ability to stabilize into the flow and to cross the pass. A tentative optimal layout was eventually highlighted. Further tests with other fish species (Common Nase – Chondrostoma nasus) confirmed that their crossing capacity was not hindered by the bed elements.
