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Behavioural response of downstream migrating European eel (Anguilla anguilla) to electric fields under static and flowing water conditions

Behavioural response of downstream migrating European eel (Anguilla anguilla) to electric fields under static and flowing water conditions
Behavioural response of downstream migrating European eel (Anguilla anguilla) to electric fields under static and flowing water conditions
Like many other species of diadromous fish, the European eel (Anguilla anguilla) is threatened by entrainment at hydropower intakes and resultant injury and mortality during passage through turbines. Historically, physical screens have been installed to prevent European eel access to intakes but these are not wholly effective and can incur high costs of construction and maintenance, especially when regulations require screen retrofits with increasingly fine mesh. There is interest in the use of potentially less expensive behavioural guidance methods to block or guide eel movements. Electric barriers have been developed to guide several species of fish, but information relating to their effectiveness for European eel is limited. In this study, two experiments were conducted to quantify the response of downstream migrating adult (silver-phase) European eel to electric fields and the effectiveness of electricity to block movements. First, a static water tank was used to identify the field strengths (Vcm−1) required to induce threshold responses for three key behaviours (twitch, loss of orientation and tetany) across three different pulsed direct current (PDC) electric waveforms (single pulse-2 Hz, double pulse-2 Hz and single pulse-10 Hz) (Experiment 1). Second, a recirculatory flume was used to investigate how avoidance responses (acceleration, change in orientation and rejection) differed between two water velocity regimes [0.5 ms−1 and 1.0 ms−1] and two field strengths [≈ 0.15 Vcm−1 and ≈ 0.3 Vcm−1] identified during the first experiment (Experiment 2). In Experiment 1, lower electric field strengths were needed to elicit tetany under the single pulse-10 Hz and single pulse-2 Hz compared to the double pulse-2 Hz waveform, but there was no effect of waveform for the other behaviours. In Experiment 2, avoidance was less frequent (31.4%) under the high compared with the low (74.5%) velocity, but electric field strength did not influence the response exhibited. This study provides insights into the potential use of electric fields to deter European eel. The effectiveness of electric barriers to block downstream migrating eel are likely limited at higher water velocities.
Anguilliform, behaviour, electric fields, migration, pulsed direct current
0925-8574
Miller, Mhairi
eaa273db-109e-4e57-9346-192c1ef977c3
de Bie, Jasper
b0520a90-7cba-4885-8518-3ee0857a44e7
Sharkh, Suleiman
c8445516-dafe-41c2-b7e8-c21e295e56b9
Kemp, Paul
9e33fba6-cccf-4eb5-965b-b70e72b11cd7
Miller, Mhairi
eaa273db-109e-4e57-9346-192c1ef977c3
de Bie, Jasper
b0520a90-7cba-4885-8518-3ee0857a44e7
Sharkh, Suleiman
c8445516-dafe-41c2-b7e8-c21e295e56b9
Kemp, Paul
9e33fba6-cccf-4eb5-965b-b70e72b11cd7

Miller, Mhairi, de Bie, Jasper, Sharkh, Suleiman and Kemp, Paul (2021) Behavioural response of downstream migrating European eel (Anguilla anguilla) to electric fields under static and flowing water conditions. Ecological Engineering, 172, [106397]. (doi:10.1016/j.ecoleng.2021.106397).

Record type: Article

Abstract

Like many other species of diadromous fish, the European eel (Anguilla anguilla) is threatened by entrainment at hydropower intakes and resultant injury and mortality during passage through turbines. Historically, physical screens have been installed to prevent European eel access to intakes but these are not wholly effective and can incur high costs of construction and maintenance, especially when regulations require screen retrofits with increasingly fine mesh. There is interest in the use of potentially less expensive behavioural guidance methods to block or guide eel movements. Electric barriers have been developed to guide several species of fish, but information relating to their effectiveness for European eel is limited. In this study, two experiments were conducted to quantify the response of downstream migrating adult (silver-phase) European eel to electric fields and the effectiveness of electricity to block movements. First, a static water tank was used to identify the field strengths (Vcm−1) required to induce threshold responses for three key behaviours (twitch, loss of orientation and tetany) across three different pulsed direct current (PDC) electric waveforms (single pulse-2 Hz, double pulse-2 Hz and single pulse-10 Hz) (Experiment 1). Second, a recirculatory flume was used to investigate how avoidance responses (acceleration, change in orientation and rejection) differed between two water velocity regimes [0.5 ms−1 and 1.0 ms−1] and two field strengths [≈ 0.15 Vcm−1 and ≈ 0.3 Vcm−1] identified during the first experiment (Experiment 2). In Experiment 1, lower electric field strengths were needed to elicit tetany under the single pulse-10 Hz and single pulse-2 Hz compared to the double pulse-2 Hz waveform, but there was no effect of waveform for the other behaviours. In Experiment 2, avoidance was less frequent (31.4%) under the high compared with the low (74.5%) velocity, but electric field strength did not influence the response exhibited. This study provides insights into the potential use of electric fields to deter European eel. The effectiveness of electric barriers to block downstream migrating eel are likely limited at higher water velocities.

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ECOLENG-D-20-01165 - Accepted Manuscript
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Accepted/In Press date: 11 August 2021
e-pub ahead of print date: 13 September 2021
Published date: December 2021
Additional Information: Funding Information: This study was funded by the Electric Power Research Institute (EPRI). We thank Paul Jacobson (EPRI) for the coordination of this project, Scott Miehls (USGS) for the loan of pulser unit, and Steve Walk (USGS) for the modification of pulser units for experimentation. We also thank Dr. Toru Tsuzaki for his assistance in the experimental set-up, sourcing and collection of eel. Finally, we thank Terry Smith for catching and providing us with the eel for this study. Publisher Copyright: © 2021
Keywords: Anguilliform, behaviour, electric fields, migration, pulsed direct current

Identifiers

Local EPrints ID: 451328
URI: http://eprints.soton.ac.uk/id/eprint/451328
ISSN: 0925-8574
PURE UUID: 054b2f0e-3813-494a-bfda-a437f2891be2
ORCID for Suleiman Sharkh: ORCID iD orcid.org/0000-0001-7335-8503
ORCID for Paul Kemp: ORCID iD orcid.org/0000-0003-4470-0589

Catalogue record

Date deposited: 21 Sep 2021 16:30
Last modified: 19 Nov 2022 05:02

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Contributors

Author: Mhairi Miller
Author: Jasper de Bie
Author: Suleiman Sharkh ORCID iD
Author: Paul Kemp ORCID iD

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