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Effectiveness of horizontally and vertically oriented wedge-wire screens to guide downstream moving juvenile chub (Squalius cephalus)

Effectiveness of horizontally and vertically oriented wedge-wire screens to guide downstream moving juvenile chub (Squalius cephalus)
Effectiveness of horizontally and vertically oriented wedge-wire screens to guide downstream moving juvenile chub (Squalius cephalus)

Physical screens are commonly installed to prevent downstream moving fish from entering dangerous areas (e.g. intakes to hydropower turbines, irrigation canals, and fish farms), and divert them to preferred alternative routes (e.g. bypass systems). In northern temperate regions, assessments of the functioning of screens have largely focused on diadromous species (e.g. salmon and eel), while ignoring those with other life history characteristics. Recent developments in physical screens include the usage of horizontally aligned bars as opposed to traditional vertical ones, but a direct comparison in terms of guidance remains untested. To address this and aid in the development of successful screens for the wider fish community, this study compared the efficacy of wedge-wire screens with horizontally and vertically oriented bars to block and divert downstream moving groups of five chub (Squalius cephalus) to a bypass channel installed in a recirculating flume under two discharge regimes. Hydrodynamics differed between horizontal and vertical screens under both flows; the vertical configuration created a higher velocity gradient towards the bypass. Total guidance (the number of bypass entries as a percentage of the number of approaches) was generally low (mean = 17.3% for all treatments), the highest being recorded for the horizontal screen under low discharge (25.3%). Rejections and holding station events, both proxies for fish exhibiting avoidance of the hydrodynamic conditions created by the screen, were lowest under this treatment. Horizontal performed better than vertical screens in guiding fish to the bypass under low but not high discharge. The results confirm that screen functioning is dependent on hydrodynamic conditions as well as the fish's behavioural response.

Cyprinidae, Fish passage, Groups, Guidance, Wedge-wire screen
0925-8574
127-134
de Bie, Jasper
064ae5a8-77bf-4197-9496-9540e26a585a
Peirson, Graeme
d51969a8-c948-448a-9aa6-8a466c69aedd
Kemp, Paul S.
9e33fba6-cccf-4eb5-965b-b70e72b11cd7
de Bie, Jasper
064ae5a8-77bf-4197-9496-9540e26a585a
Peirson, Graeme
d51969a8-c948-448a-9aa6-8a466c69aedd
Kemp, Paul S.
9e33fba6-cccf-4eb5-965b-b70e72b11cd7

de Bie, Jasper, Peirson, Graeme and Kemp, Paul S. (2018) Effectiveness of horizontally and vertically oriented wedge-wire screens to guide downstream moving juvenile chub (Squalius cephalus). Ecological Engineering, 123, 127-134. (doi:10.1016/j.ecoleng.2018.07.038).

Record type: Article

Abstract

Physical screens are commonly installed to prevent downstream moving fish from entering dangerous areas (e.g. intakes to hydropower turbines, irrigation canals, and fish farms), and divert them to preferred alternative routes (e.g. bypass systems). In northern temperate regions, assessments of the functioning of screens have largely focused on diadromous species (e.g. salmon and eel), while ignoring those with other life history characteristics. Recent developments in physical screens include the usage of horizontally aligned bars as opposed to traditional vertical ones, but a direct comparison in terms of guidance remains untested. To address this and aid in the development of successful screens for the wider fish community, this study compared the efficacy of wedge-wire screens with horizontally and vertically oriented bars to block and divert downstream moving groups of five chub (Squalius cephalus) to a bypass channel installed in a recirculating flume under two discharge regimes. Hydrodynamics differed between horizontal and vertical screens under both flows; the vertical configuration created a higher velocity gradient towards the bypass. Total guidance (the number of bypass entries as a percentage of the number of approaches) was generally low (mean = 17.3% for all treatments), the highest being recorded for the horizontal screen under low discharge (25.3%). Rejections and holding station events, both proxies for fish exhibiting avoidance of the hydrodynamic conditions created by the screen, were lowest under this treatment. Horizontal performed better than vertical screens in guiding fish to the bypass under low but not high discharge. The results confirm that screen functioning is dependent on hydrodynamic conditions as well as the fish's behavioural response.

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De Bie et al. 2018_main - Accepted Manuscript
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More information

Accepted/In Press date: 29 July 2018
e-pub ahead of print date: 10 September 2018
Published date: 1 November 2018
Keywords: Cyprinidae, Fish passage, Groups, Guidance, Wedge-wire screen

Identifiers

Local EPrints ID: 425054
URI: http://eprints.soton.ac.uk/id/eprint/425054
ISSN: 0925-8574
PURE UUID: 6611633a-0ad6-4ed9-95ca-04e33b70334a
ORCID for Paul S. Kemp: ORCID iD orcid.org/0000-0003-4470-0589

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Date deposited: 09 Oct 2018 16:30
Last modified: 07 Oct 2020 06:33

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Contributors

Author: Jasper de Bie
Author: Graeme Peirson
Author: Paul S. Kemp ORCID iD

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