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The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification

The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification
The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification

Globally, freshwaters are the most degraded and threatened of all ecosystems. In northern temperate regions, beaver (Castor spp.) reintroductions are increasingly used as a low-cost and self-sustaining means to restore river corridors. River modifications by beavers can increase availability of suitable habitat for fish, including salmonids. This study investigated the response of a population of brown trout (Salmo trutta) to reintroduced Eurasian beaver (Castor fiber) habitat modifications in northern Scotland. The field site comprised two streams entering a common loch; one modified by beavers, the other unaltered. Electrofishing and PIT telemetry surveys indicated abundance of post-young-of-the-year (post-YOY) trout was higher in the modified stream. Considering juvenile year groups (YOY and post-YOY) combined, abundance and density varied with year and season. In the modified stream, fork length and mass were greater, there was a greater variety of age classes, and mean growth was positive during all seasons. Beavers had profound effects on the local brown trout population that promoted higher abundances of larger size classes. This study provides important insight into the possible future effect of beavers on freshwater ecosystems.

beaver dams, beaver habitats, beaver ponds, ecosystem engineers, salmonids
0706-652X
1650–1660
Needham, Robert James
49f2cc00-3c06-4f8b-a127-c2e735b43bfd
Gaywood, Martin J.
9ef47618-701c-4f9d-b8b1-c232946c8d12
Tree, Angus
45a5b121-3e02-4462-855e-f04a3b23d212
Sotherton, Nick
1a532984-645d-46c8-b128-b1c5e2e7e9c5
Roberts, Dylan
24fa11cf-1163-4bb1-9714-54bbd1285dfe
Bean, Colin
7dd188cf-a423-422e-87e1-1293a484b0f6
Kemp, Paul
9e33fba6-cccf-4eb5-965b-b70e72b11cd7
Needham, Robert James
49f2cc00-3c06-4f8b-a127-c2e735b43bfd
Gaywood, Martin J.
9ef47618-701c-4f9d-b8b1-c232946c8d12
Tree, Angus
45a5b121-3e02-4462-855e-f04a3b23d212
Sotherton, Nick
1a532984-645d-46c8-b128-b1c5e2e7e9c5
Roberts, Dylan
24fa11cf-1163-4bb1-9714-54bbd1285dfe
Bean, Colin
7dd188cf-a423-422e-87e1-1293a484b0f6
Kemp, Paul
9e33fba6-cccf-4eb5-965b-b70e72b11cd7

Needham, Robert James, Gaywood, Martin J., Tree, Angus, Sotherton, Nick, Roberts, Dylan, Bean, Colin and Kemp, Paul (2021) The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification. Canadian Journal of Fisheries and Aquatic Sciences, 78 (11), 1650–1660. (doi:10.1139/cjfas-2021-0023).

Record type: Article

Abstract

Globally, freshwaters are the most degraded and threatened of all ecosystems. In northern temperate regions, beaver (Castor spp.) reintroductions are increasingly used as a low-cost and self-sustaining means to restore river corridors. River modifications by beavers can increase availability of suitable habitat for fish, including salmonids. This study investigated the response of a population of brown trout (Salmo trutta) to reintroduced Eurasian beaver (Castor fiber) habitat modifications in northern Scotland. The field site comprised two streams entering a common loch; one modified by beavers, the other unaltered. Electrofishing and PIT telemetry surveys indicated abundance of post-young-of-the-year (post-YOY) trout was higher in the modified stream. Considering juvenile year groups (YOY and post-YOY) combined, abundance and density varied with year and season. In the modified stream, fork length and mass were greater, there was a greater variety of age classes, and mean growth was positive during all seasons. Beavers had profound effects on the local brown trout population that promoted higher abundances of larger size classes. This study provides important insight into the possible future effect of beavers on freshwater ecosystems.

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Needham et al. Trout Beaver CJFAS RESUBMISSION
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Accepted/In Press date: 10 April 2021
Published date: November 2021
Additional Information: Funding Information: We thank the Swift family for access to the field site and accommodation during survey work, and ICER staff, Rob Branch and Fred Swift for their assistance with field work and data collection. The Ph.D. was funded by the NERC Doctoral Training Partnership (SPITFIRE) based at the University of Southampton. Additional funding was provided by the Game and Wildlife Conservation Trust, Trout and Salmon Association and NatureScot. We thank the associated editor and two anonymous reviewers for comments on an earlier version of this manuscript. Publisher Copyright: © 2021 The Author(s).
Keywords: beaver dams, beaver habitats, beaver ponds, ecosystem engineers, salmonids

Identifiers

Local EPrints ID: 448320
URI: http://eprints.soton.ac.uk/id/eprint/448320
ISSN: 0706-652X
PURE UUID: 24fb49dc-588b-499d-8c72-680786ebc1d6
ORCID for Paul Kemp: ORCID iD orcid.org/0000-0003-4470-0589

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Date deposited: 20 Apr 2021 16:32
Last modified: 17 Mar 2024 06:30

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Contributors

Author: Martin J. Gaywood
Author: Angus Tree
Author: Nick Sotherton
Author: Dylan Roberts
Author: Colin Bean
Author: Paul Kemp ORCID iD

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