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Masking a fish's detection of environmental stimuli: application to improving downstream migration at river infrastructure

Masking a fish's detection of environmental stimuli: application to improving downstream migration at river infrastructure
Masking a fish's detection of environmental stimuli: application to improving downstream migration at river infrastructure

According to Signal Detection Theory, the ability to detect a stimulus (discriminability, d') is inversely related to the magnitude of internal and external noise. In this study, downstream moving brown trout Salmo trutta were used to investigate whether external hydrodynamic noise (in this case turbulence) could mask a signal that induced an unwanted response, such as rejecting accelerating velocity gradients commonly encountered at entrances to fish bypass channels. S. trutta behaviour was quantified in the absence (control) or presence of an accelerating velocity gradient created by an unconstricted or constricted channel, respectively, under two levels (low and high) of background turbulent kinetic energy (hydrodynamic noise). Experiments were conducted in an indoor recirculating flume in the dark and a range of passage metrics were quantified. Under the control condition, most (ca. 91%) S. trutta passed, usually oriented downstream (67%), with minimal delay (median 0.13 min). In comparison, fewer S. trutta (ca. 43%) passed under constricted conditions, they tended to orient facing into the flow (ca. 64%) and delay was greater (median > 20 min). When viewed from a coarse-scale perspective, discriminability of the velocity gradient was lower when turbulence was high suggesting masking of the signal occurred. However, the resulting increase in the percentage of fish that passed, decrease in time to pass and reduction in the distance at which S. trutta reacted (switched orientation) was subtle and non-significant. Despite the mixed results obtained, the use of masking to manipulate an animal's perception of environmental stimuli as a fisheries management tool is conceptually valid and the results of this experiment present a useful stepping stone for future research.

brown trout, bypass entrance, fish behaviour, sensory ecology, signal detection theory, velocity gradient
0022-1112
Kerr, James R.
cfdf2892-19c2-4206-9416-848b2b0f672c
Kemp, Paul S.
9e33fba6-cccf-4eb5-965b-b70e72b11cd7
Kerr, James R.
cfdf2892-19c2-4206-9416-848b2b0f672c
Kemp, Paul S.
9e33fba6-cccf-4eb5-965b-b70e72b11cd7

Kerr, James R. and Kemp, Paul S. (2018) Masking a fish's detection of environmental stimuli: application to improving downstream migration at river infrastructure. Journal of Fish Biology. (doi:10.1111/jfb.13812).

Record type: Article

Abstract

According to Signal Detection Theory, the ability to detect a stimulus (discriminability, d') is inversely related to the magnitude of internal and external noise. In this study, downstream moving brown trout Salmo trutta were used to investigate whether external hydrodynamic noise (in this case turbulence) could mask a signal that induced an unwanted response, such as rejecting accelerating velocity gradients commonly encountered at entrances to fish bypass channels. S. trutta behaviour was quantified in the absence (control) or presence of an accelerating velocity gradient created by an unconstricted or constricted channel, respectively, under two levels (low and high) of background turbulent kinetic energy (hydrodynamic noise). Experiments were conducted in an indoor recirculating flume in the dark and a range of passage metrics were quantified. Under the control condition, most (ca. 91%) S. trutta passed, usually oriented downstream (67%), with minimal delay (median 0.13 min). In comparison, fewer S. trutta (ca. 43%) passed under constricted conditions, they tended to orient facing into the flow (ca. 64%) and delay was greater (median > 20 min). When viewed from a coarse-scale perspective, discriminability of the velocity gradient was lower when turbulence was high suggesting masking of the signal occurred. However, the resulting increase in the percentage of fish that passed, decrease in time to pass and reduction in the distance at which S. trutta reacted (switched orientation) was subtle and non-significant. Despite the mixed results obtained, the use of masking to manipulate an animal's perception of environmental stimuli as a fisheries management tool is conceptually valid and the results of this experiment present a useful stepping stone for future research.

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Kerr_et_al-2018-Journal_of_Fish_Biology - Version of Record
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More information

Accepted/In Press date: 20 September 2018
e-pub ahead of print date: 21 December 2018
Keywords: brown trout, bypass entrance, fish behaviour, sensory ecology, signal detection theory, velocity gradient

Identifiers

Local EPrints ID: 427204
URI: http://eprints.soton.ac.uk/id/eprint/427204
ISSN: 0022-1112
PURE UUID: 97701770-ef61-4b24-897f-486b37403199
ORCID for James R. Kerr: ORCID iD orcid.org/0000-0002-2990-7293
ORCID for Paul S. Kemp: ORCID iD orcid.org/0000-0003-4470-0589

Catalogue record

Date deposited: 08 Jan 2019 17:30
Last modified: 07 Oct 2020 02:01

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