Performance of a fish pass for multiple species: Scale model investigation

Abstract

Artificial fish passes are often the most effective solution to restore the ecological continuity of a dammed river. Such a pass can be built for specifically targeted fish species, based on the existing knowledge on its swimming capacity and behaviour. Usually, a wider range of possible species are present in the river and may use the fish pass. In the present study, a vertical slot fish pass has been designed for salmonid fish (namely Atlantic salmon Salmo Salar). This fish pass layout was initially tested using a scale model where juvenile fish were introduced. The study has now been extended to other species, some of them having weaker swimming capacity: bleak (Alburnus alburnus); chub (Squalius cephalus); and bullhead (Cottus gobio). Fish behaviour in the pass was observed using PIT-tag and video. PIT-tag tracking enabled to characterise the capability of the fish to cross the whole fish pass. Video recording was used to analyse in more details the behaviour of the fish in a specific pool.