Evaluation of the Iberian barbel resting behavior in vertical slot fishways: A two-dimensional Eulerian Lagrangian Agent based approach

Fishways design requires careful evaluation of hydraulic and biological requirements. This study presents a Eulerian-Lagrangian Agent Based Model of fish migration through Vertical Slot Fishways which relies on 2D flow simulations. The model, provided as a Python toolbox named t-ELAM-acPy_2D, integrates two-dimensional flow fields with an agent-based description of fish movement and behavior. t-ELAM-acPy_2D represents fish upstream movement using multiple behavioral states, including resting responses, a key element for cyprinid movement. The model also performs an energy-expenditure analysis, using a real-time, dynamic flow field. It was calibrated and validated across different fishway configurations, using Iberian barbel (Luciobarbus bocagei) as fish targeted species. The model successfully reproduced fish habitat spatial distribution, ascent times and, to a limited extent, passage efficiency. The results show that the toolbox can efficiently support design, optimization, and evaluation of different fishway configurations.