Use of electromyogram telemetry to assess the behavior of the Iberian barbel (Luciobarbus bocagei Steindachner, 1864) in a pool-type fishway.

Abstract

Decline in fish species populations due to river regulation by dams and weirs promoted the development of fishways, which are becoming one of the most common measures for the restoration of connectivity in rivers. Fishways efficiency can be species specific and thus monitoring and evaluation, and subsequent adjustments to design and hydraulic features, are required to inform potential users prior to installation. In this study we tested the applicability of electromyogram telemetry to study the swimming behavior of a cyprinid potamodromous species, the Iberian barbel Luciobarbus bocagei Steindachner, 1864, in an experimental pool-type fishway. In total, 24 barbels were used in the experiment, 12 of which were tagged with EMG radio transmitters equipped with electrodes that register muscle activity, while the other 12 untagged fish were used as control. For tagged fish, a relationship between swimming speed and EMG telemetry signals was developed in a swimming tunnel, which was later used to assess barbels swimming behavior within the experimental fishway. Tagged fish exhibited high passage success and anaerobic burst swimming was only required to move through the submerged orifices of the fishway. Barbels spent successively less time when transversing the pools in the upstream direction. Measured hydraulic variables that were related with barbels’ swimming speed within the fishways were the water velocity, turbulent kinetic energy, turbulence intensity and, especially, the horizontal component of Reynolds shear stress, highlighting the importance of these parameters when designing pool-type fishways.