Author(s): Md Aminul Islam Shagor; Md. Sajjad Hossain Tusher; Tom A. Langen; Haitham Ghamry; Christos Katopodis; Abul B. M. Baki

Linked Author(s): Haitham Ghamry, Christos Katopodis, Abul Baki

Keywords: Explored area; Fish passage; Instream boulder placement; Movement ecology; Salmonids; Spatial variability; Fish trajectory path length

Abstract: Hydraulic complexity strongly influences fish movement and energy use, making it a key factor in the design of nature-like fishways. This study examines the fish migratory pathways and associated energy consumption of juvenile Atlantic salmon (Salmo salar) and Rainbow trout (Oncorhynchus mykiss) across ten nature-like fishways, including rock-ramp (random and regular) and rock-weir (I-shape, and V-shape) under low (0.06 m3/s) and high(0.07 m3/s)-flow conditions. Fish trajectories captured by synchronized cameras were analyzed to quantify explored area (EA), Fish trajectory Path Length (FTPL), and spatial probability P H(x,y) using 1.0 cm kernel density estimation. Preliminary findings show that denser boulder patterns (λ = 5.4 %) promote greater spatial exploration (EA = 1.5 %) and longer pathways (FTPL = 3.6 m), indicating higher energy demand but improved passage connectivity. Ongoing analyses will integrate drag-based propulsive energy consumption of summing fish to assess hydrodynamic efficiency and identify energetically optimal migratory routes. The results will support the development of effective fish passage facilities for hydraulically and behaviorally efficient nature-like fishways.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.125

Year: 2026