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Deep learning models used to detect fish movement over resistivity counters

Deep learning models used to detect fish movement over resistivity counters
Deep learning models used to detect fish movement over resistivity counters

Diadromous fish are one of the most threatened groups of fish species, being subject to pressures from freshwater, estuarine and marine environments. Of these fish, Atlantic salmon is the most economically important and increasingly threatened. To assess salmonid (Atlantic salmon and sea trout) stocks, resistivity counters have been widely used. However, verification of data from the counters can be challenging due to miscounts, misidentification and biases in human verification of fish counts. We applied deep learning models to identify diadromous fish using continuous electrical resistivity data from resistivity fish counters. Our models were tested on three rivers (Frome, Fowey and Test in the South and South-West of England) and compared with a minimum of one year's manually validated data. We detected fish signals from background noise with an F1-score of 99%, large from small fish (≥30 cm) with a precision of 95%, and an increase of >38% small and large fish waveforms. The F1-score for salmonids was 92%, and a significantly greater proportion (>173%) of upstream-moving large salmonids (≥30 cm) were detected compared to manual methods. To date, abundance estimates for resistivity counters have only been applied to salmonids because of labour-intensive waveform identification. Using deep learning methods, we quantified salmonids and other diadromous fish with varying accuracies. Our method can be applied to resistivity counters to detect diadromous fish globally, reducing human bias and improving detection accuracy.

Atlantic salmon, Automated detection, Convolutional neural network, Diadromous fish, Fish counters, Machine learning
1574-9541
Elliott, Sophie A.M.
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Boraiah, Keerthan
ffb98148-0901-49db-a9a3-8a1726a8f7db
Tham, Chun Kee
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Beaumont, William R.C.
8e2f5fa9-0830-49b9-8400-1a11625a103c
Elsmere, Paul
019596f6-01b4-408e-95dc-50f72a5388f6
Scott, Luke
aea36019-bdcf-4f1a-b9d9-4d29ce4c0f00
Fewings, Adrian
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Elliott, Sophie A.M.
80952a72-2906-4aa4-9d8e-8e51a4fc3a06
Boraiah, Keerthan
ffb98148-0901-49db-a9a3-8a1726a8f7db
Tham, Chun Kee
bb31bdc7-a2f6-4464-9577-5112fdd51e81
Beaumont, William R.C.
8e2f5fa9-0830-49b9-8400-1a11625a103c
Elsmere, Paul
019596f6-01b4-408e-95dc-50f72a5388f6
Scott, Luke
aea36019-bdcf-4f1a-b9d9-4d29ce4c0f00
Fewings, Adrian
45e7ecc9-2210-4efc-a060-7c14107102da

Elliott, Sophie A.M., Boraiah, Keerthan, Tham, Chun Kee, Beaumont, William R.C., Elsmere, Paul, Scott, Luke and Fewings, Adrian (2026) Deep learning models used to detect fish movement over resistivity counters. Ecological Informatics, 94, [103606]. (doi:10.1016/j.ecoinf.2026.103606).

Record type: Article

Abstract

Diadromous fish are one of the most threatened groups of fish species, being subject to pressures from freshwater, estuarine and marine environments. Of these fish, Atlantic salmon is the most economically important and increasingly threatened. To assess salmonid (Atlantic salmon and sea trout) stocks, resistivity counters have been widely used. However, verification of data from the counters can be challenging due to miscounts, misidentification and biases in human verification of fish counts. We applied deep learning models to identify diadromous fish using continuous electrical resistivity data from resistivity fish counters. Our models were tested on three rivers (Frome, Fowey and Test in the South and South-West of England) and compared with a minimum of one year's manually validated data. We detected fish signals from background noise with an F1-score of 99%, large from small fish (≥30 cm) with a precision of 95%, and an increase of >38% small and large fish waveforms. The F1-score for salmonids was 92%, and a significantly greater proportion (>173%) of upstream-moving large salmonids (≥30 cm) were detected compared to manual methods. To date, abundance estimates for resistivity counters have only been applied to salmonids because of labour-intensive waveform identification. Using deep learning methods, we quantified salmonids and other diadromous fish with varying accuracies. Our method can be applied to resistivity counters to detect diadromous fish globally, reducing human bias and improving detection accuracy.

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More information

Accepted/In Press date: 6 January 2026
e-pub ahead of print date: 21 January 2026
Published date: 6 February 2026
Keywords: Atlantic salmon, Automated detection, Convolutional neural network, Diadromous fish, Fish counters, Machine learning

Identifiers

Local EPrints ID: 510712
URI: http://eprints.soton.ac.uk/id/eprint/510712
ISSN: 1574-9541
PURE UUID: 0effe1da-2e08-4281-9dfe-2281ccafaed2
ORCID for Chun Kee Tham: ORCID iD orcid.org/0009-0004-3275-7793

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Date deposited: 17 Apr 2026 16:47
Last modified: 18 Apr 2026 02:29

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Contributors

Author: Sophie A.M. Elliott
Author: Keerthan Boraiah
Author: Chun Kee Tham ORCID iD
Author: William R.C. Beaumont
Author: Paul Elsmere
Author: Luke Scott
Author: Adrian Fewings

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