Assessing the behavioural response of the Iberian barbel (Barbus bocagei) in a pool-and-weir type fishway prototype using EMG telemetry

Portuguese rivers are particularly regulated by dams and weirs that, by deterring fish migration, contribute to species and habitat loss. Fishways can minimize part of the negative impacts associated with these obstructions but their efficiency must be guaranteed by adjusting the design of the facilities to the potential users. In this study we used an experimental pool-and-weir type fishway to study the swimming behaviour of the Iberian barbel Barbus bocagei Steindachner, 1865. This cyprinid is a potamodromous species widely spread in Portugal and Spain. The barbels used in this experiment were tagged with EMG radio transmitters equipped with electrodes that register the muscle activity. A relationship was developed in a swimming tunnel for all tagged fish whereby swim speed could be estimated from the EMG telemetry signals. The behaviour of the tagged barbels during the fish passage was video recorded and compared with the EMG signal (i.e., swim speed). Results suggest that EMG telemetry can be successfully use to study barbel’s swimming behaviour in a pool-and-weir type fishway, in view of adapting the dimensional criteria of this facilities to target species