An Experimental Approach for the Quantitative Assessment of Downstream Swimming Fish Behavior

Behavior of fish influences the mortality risk during turbine and pump passages. Knowledge about species‐specific behavior and its triggers is necessary for improving numerical models and the development of autonomous sensor probes to estimate fish mortality in turbines and pumps. A primary objective of the RETERO project is the study of fish behavior in hydraulic conditions similar to turbine and pump intakes in controlled conditions. For this purpose, an experimental conduit was constructed at the Hubert‐Engels Laboratory of the TUD Dresden University of Technology (Germany) equipped with a 3D camera infrared tracking system. The conduit was designed to model hydraulic conditions typical for turbine and pump intakes. In the experimental setup, the effects of flow velocities exceeding the maximum swim speed of fish, as well as spatial velocity gradients and illumination conditions on the fish behavior are studied. The data from brown trout ( Salmo trutta ) allow for an analysis of how these fish react to flow accelerations and velocities surpassing their sprint speed, using quantitative metrics for movement and activity. An initial evaluation of these experiments highlights the potential of this approach for further research.