Upstream directed fish migration in the German federal waterway system is blocked by many dams. Building efficient fishways is a way to mitigate this ecological problem, but to determine efficiency using field or laboratory studies is costly and time-consuming. A numerical model simulating fish movement in spatial and temporal scales of decimeters and seconds, respectively, can support selection of competing fishway designs and contribute to scientific understanding of their performance. The Eulerian-Lagrangian-agent method (ELAM) was chosen to develop a new individual-based model, “ELAM-de”. 3D computational fluid dynamics input on arbitrary polyhedral meshes was obtained from the open source toolbox OpenFOAM®. Six behavior patterns were derived from movement data of live brown trout under two different flow fields collected in a large flume (length × width × water depth was 11.78 m×2.50 m×0.60 m). The behavior patterns were used to develop, calibrate, and validate the individual-based model. For the first flow field, containing a high-velocity jet, calibrated model predictions minus observed data were within ±18.3 percentage points or less for all six patterns. Validation in the second, more homogeneous flow field obtained qualitative agreement for five patterns using identical model parameters. Advective acceleration magnitude and hydrostatic pressure were identified as key hydraulic stimuli to reproduce observed behavior. Acclimatization through simple memory functions was incorporated as a critical process for the individual-based model. ELAM-de produces estimates for flume passage success and metabolic cost, which – after successful further validation – can be used to compare efficiencies of alternative fishway designs.    «

Upstream directed fish migration in the German federal waterway system is blocked by many dams. Building efficient fishways is a way to mitigate this ecological problem, but to determine efficiency using field or laboratory studies is costly and time-consuming. A numerical model simulating fish movement in spatial and temporal scales of decimeters and seconds, respectively, can support selection of competing fishway designs and contribute to scientific understanding of their performance. The Eul...    »