EFFECTS OF WATER VELOCITY AND TURBULENCE ON THE BEHAVIOUR OF IBERIAN BARBEL (LUCIOBARBUS BOCAGEI, STEINDACHNER 1864) IN AN EXPERIMENTAL POOL-TYPE FISHWAY

The restoration of fish passage has been focused on anadromous fish species, whilst studies accommodating passage of coarse species have often been considered incidental, yet frequently these are the predominant group of species encountered in rivers. In addition, fishway designs depend greatly on the interplay between hydraulics and biomechanics, yet very little data are available on the responses to specific hydraulic settings for these species. This study aims to explore the effects of water velocity and turbulence on the behaviour of a cyprinid species - the Iberian barbel Luciobarbus bocagei (Steindachner, 1864) - particularly their upstream movements upon different discharges (38.5 to 77.0 L . s(-1)), through an indoor full scale pool-type fishway prototype. Larger adults had a higher passage success (mean = 79%) and took less time (mean +/- SD (min): 5.7 +/- 1.3) to negotiate the entire six pool fishway, when compared to small adults. Correlation analysis between hydraulic variables and fish transit time yielded different results. Correlations were found to be the highest between the horizontal component of Reynolds shear stress and fish transit time, particularly for smaller size-individuals (r = -0.45; p < 0.001), highlighting this variable as a key-parameter which strongly determines the movements of Iberian barbel. The present study identified key factors on Iberian barbel movements that may have direct application to future fishway designs for this species and for other 'weak' swimmers. Copyright (C) 2010 John Wiley & Sons, Ltd.