Location

Oregon State University

Start Date

27-6-2013 3:10 PM

End Date

27-6-2013 3:30 PM

Description

Pool-type fishways are the most common types of fishwaysbuilt at small weirs; yet, their performance for restoring connectivity for fish species with limited swimming ability has not been fully explored. To address this concern and ease upstream fish passage, increasing interest has been expressed in the placement of artificial substrata in the bottom of these facilities. Nevertheless, no study has so far considered the effect of boulder spacing (i.e. density) and flow discharge on the success and timing of upstream movements of migrating cyprinids. The aim of this study was to assess the performance of two boulder density designs with increasing flows. Passage success was tested for a potamodromous cyprinid, the Iberian barbel (Luciobarbus bocagei), in an experimental but full-scale pool-type fishway. Although no significant differences in passage success were detected between boulder spacing (high density: 35%; low density: 40%), increased flows induced a higher proportion (P< 0.05) of successful negotiations (50%), relative to low flow discharges (25%). Both factors did not interact. Furthermore, under higher flow discharge, fish took significantly less time (P< 0.05) to ascend the fishway with the higher (mean ± standard deviation (SD): 5.3 ± 4.2 min.) versus the lower boulder density (mean ± SD: 12.1 ± 6.5 min.). Results showed that although fish passage success was independent of boulder density, a tighter configuration combined with higher flow discharge can be beneficial, as it was found to reduce transit time. However, if flow volume is a constraint, a low density design should be employed instead.

Comments

José Maria Santos is an assistant researcher at Instituto Superior de Agronomia, Technical University of Lisbon, Portugal. His research interests focus primarily on ecohydraulics, fish passes and freshwater fishecology. His PhD (2004) was focused on the effects of flow regulations on fish population and communities and the role of different types of fish passes. Since 1997, he has collaborated in several research projects encompassing specific areas such as ecohydraulics, monitoring and evaluation of fish passes and spatio-temporal organization of fish communities and populations.

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Jun 27th, 3:10 PM Jun 27th, 3:30 PM

Concurrent Sessions D: Design and Performance of Roughened Channels - Response of a Non-Salmonid Fish to Boulder Density and Flow Discharge in an Experimental Pool-Type Fishway

Oregon State University

Pool-type fishways are the most common types of fishwaysbuilt at small weirs; yet, their performance for restoring connectivity for fish species with limited swimming ability has not been fully explored. To address this concern and ease upstream fish passage, increasing interest has been expressed in the placement of artificial substrata in the bottom of these facilities. Nevertheless, no study has so far considered the effect of boulder spacing (i.e. density) and flow discharge on the success and timing of upstream movements of migrating cyprinids. The aim of this study was to assess the performance of two boulder density designs with increasing flows. Passage success was tested for a potamodromous cyprinid, the Iberian barbel (Luciobarbus bocagei), in an experimental but full-scale pool-type fishway. Although no significant differences in passage success were detected between boulder spacing (high density: 35%; low density: 40%), increased flows induced a higher proportion (P< 0.05) of successful negotiations (50%), relative to low flow discharges (25%). Both factors did not interact. Furthermore, under higher flow discharge, fish took significantly less time (P< 0.05) to ascend the fishway with the higher (mean ± standard deviation (SD): 5.3 ± 4.2 min.) versus the lower boulder density (mean ± SD: 12.1 ± 6.5 min.). Results showed that although fish passage success was independent of boulder density, a tighter configuration combined with higher flow discharge can be beneficial, as it was found to reduce transit time. However, if flow volume is a constraint, a low density design should be employed instead.