Supplementary material - Downstream fish passage and swimming behaviour at a bypass gate with bottom and top opening

Supplementary_text.docx - Detailed descriptions of the experimental flume setup and physical model, fish husbandry and water quality conditions, the formulation and results of GLMMs for bypass entrance probability, observed species-specific swimming and bypass-entry behaviours, and a review of European prototype bypass systems with reported hydraulic parameters and passage efficiencies. Supplementary Figures: SF1–SF4 present the spatial distributions of the time-averaged streamwise velocity and streamwise spatial velocity gradient upstream of the FGR–bypass system for two approach-flow velocities (Uo = 0.3 and 0.5 m/s), comparing bottom and top bypass inlet openings through plan views at different depths and longitudinal profiles along the bypass axes. Supplementary Videos: SV1–SV7 illustrate species‑specific swimming, guidance, avoidance, and bypass‑entry behaviours of brown trout and barbel at bottom and top bypass inlet openings, highlighting rheotactic responses, thigmotactic interactions with structures, and contrasting individual and group‑based passage dynamics.