Ecohydraulics of pool-type fishways for the Iberian Barbal (Luciobarbus Bocagei Steindachner, 1864)

Abstract

This study analyses the impact of different hydraulic conditions on the Iberian barbel’s upstream movements in a pool-type fishway. Developed in an experiment pool-type fishway prototype and including fish of different sizes, this study investigates: i) the efficiency of passage through submerged orifices or notches; ii) the effect of velocity, turbulence and Reynolds shear stress on this species’ behaviour; iii) the suitability of straight and offset orifices to fish’s passage and, finally, iv) the efficiency of offset and straight orifices with a deflector bar for this specimens’ movements. The fishways was found to be efficient to the upstream passage of this species. Submerged orifices were preferentially used by specimens, mainly by small fish which, although their higher rheotatic capacity, showed strong difficulties to pass through the fishway. The behaviour of the latter was also the most affected by turbulence and Reynolds shear stress, which seemed to be the variables affecting fish’ movements the most. Straight orifices were found not be adequate to fish passage, even when added of a deflector bar. The results are discussed in terms of future research delineation.