Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers
1. The return of the Eurasian otter (Lutra lutra) to western Norway has sparked human–predator conflicts because otters prey on vulnerable Atlantic salmon (Salmo salar) populations. Although predation may not be the ultimate cause of salmon population declines, otters that kill adult salmon in river...
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Online Access: | https://hdl.handle.net/11250/3127240 https://doi.org/10.1111/fwb.14095 |
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ftunivbergen:oai:bora.uib.no:11250/3127240 2024-05-19T07:37:44+00:00 Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers Sortland, Lene Lennox, Robert Velle, Gaute Vollset, Knut Kambestad, Marius 2023 application/pdf https://hdl.handle.net/11250/3127240 https://doi.org/10.1111/fwb.14095 eng eng Andre: Hofseth Aqua Miljødirektoratet: 21S0629E urn:issn:0046-5070 https://hdl.handle.net/11250/3127240 https://doi.org/10.1111/fwb.14095 cristin:2146754 Freshwater Biology. 2023, 68 (7), 1176-1193. Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright 2023 The Author(s) Freshwater Biology 1176-1193 68 7 VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 Journal article Peer reviewed 2023 ftunivbergen https://doi.org/10.1111/fwb.14095 2024-04-23T23:32:31Z 1. The return of the Eurasian otter (Lutra lutra) to western Norway has sparked human–predator conflicts because otters prey on vulnerable Atlantic salmon (Salmo salar) populations. Although predation may not be the ultimate cause of salmon population declines, otters that kill adult salmon in rivers before they spawn impact the salmon spawning stock, with potential consequences for stock recruitment and ecosystem services (especially fisheries). 2. To gain insight into impacts of otter predation on salmon populations, we quantified the predation by otters on adult salmon in two rivers in western Norway using a combination of radiotelemetry and temperature loggers. We tagged 30 salmon in Aureelva and 30 salmon in Søre Vartdalselva, and tracked the salmon until they died or left the river. 3. This method identified the fates of 95% of tagged salmon. Estimated predation rates on adult salmon were 32% in Aureelva and 95% in Søre Vartdalselva. The salmon stock in Søre Vartdalselva was well below the spawning target, partly attributable to putatively additive mortality from predation by otters. Notwithstanding, we found no evidence that otters selectively killed salmon based on sex, length, health status, or activity level. 4. Salmon in Søre Vartdalselva had greater predation risk compared to salmon in Aureelva, possibly due to differences in habitat types such as availability of holding pools. The presence of more holding area in Aureelva probably provided predation refuges for adult salmon that buffered the effectiveness of otter predation. 5. Our findings emphasise that management decisions should be guided by riverspecific evaluations of impacts of predation on salmon. Otters are a very visible predator operating at the final phase of the life cycle before spawning, so predation is liable to be controversial given that salmon are now Red Listed in Norway. additive mortality, migration, selection, spawning, telemetry publishedVersion Article in Journal/Newspaper Atlantic salmon Salmo salar Lutra lutra University of Bergen: Bergen Open Research Archive (BORA-UiB) Freshwater Biology 68 7 1176 1193 |
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Open Polar |
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University of Bergen: Bergen Open Research Archive (BORA-UiB) |
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ftunivbergen |
language |
English |
topic |
VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 |
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VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 Sortland, Lene Lennox, Robert Velle, Gaute Vollset, Knut Kambestad, Marius Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers |
topic_facet |
VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 |
description |
1. The return of the Eurasian otter (Lutra lutra) to western Norway has sparked human–predator conflicts because otters prey on vulnerable Atlantic salmon (Salmo salar) populations. Although predation may not be the ultimate cause of salmon population declines, otters that kill adult salmon in rivers before they spawn impact the salmon spawning stock, with potential consequences for stock recruitment and ecosystem services (especially fisheries). 2. To gain insight into impacts of otter predation on salmon populations, we quantified the predation by otters on adult salmon in two rivers in western Norway using a combination of radiotelemetry and temperature loggers. We tagged 30 salmon in Aureelva and 30 salmon in Søre Vartdalselva, and tracked the salmon until they died or left the river. 3. This method identified the fates of 95% of tagged salmon. Estimated predation rates on adult salmon were 32% in Aureelva and 95% in Søre Vartdalselva. The salmon stock in Søre Vartdalselva was well below the spawning target, partly attributable to putatively additive mortality from predation by otters. Notwithstanding, we found no evidence that otters selectively killed salmon based on sex, length, health status, or activity level. 4. Salmon in Søre Vartdalselva had greater predation risk compared to salmon in Aureelva, possibly due to differences in habitat types such as availability of holding pools. The presence of more holding area in Aureelva probably provided predation refuges for adult salmon that buffered the effectiveness of otter predation. 5. Our findings emphasise that management decisions should be guided by riverspecific evaluations of impacts of predation on salmon. Otters are a very visible predator operating at the final phase of the life cycle before spawning, so predation is liable to be controversial given that salmon are now Red Listed in Norway. additive mortality, migration, selection, spawning, telemetry publishedVersion |
format |
Article in Journal/Newspaper |
author |
Sortland, Lene Lennox, Robert Velle, Gaute Vollset, Knut Kambestad, Marius |
author_facet |
Sortland, Lene Lennox, Robert Velle, Gaute Vollset, Knut Kambestad, Marius |
author_sort |
Sortland, Lene |
title |
Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers |
title_short |
Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers |
title_full |
Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers |
title_fullStr |
Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers |
title_full_unstemmed |
Impacts of predation by Eurasian otters on Atlantic salmon in two Norwegian rivers |
title_sort |
impacts of predation by eurasian otters on atlantic salmon in two norwegian rivers |
publishDate |
2023 |
url |
https://hdl.handle.net/11250/3127240 https://doi.org/10.1111/fwb.14095 |
genre |
Atlantic salmon Salmo salar Lutra lutra |
genre_facet |
Atlantic salmon Salmo salar Lutra lutra |
op_source |
Freshwater Biology 1176-1193 68 7 |
op_relation |
Andre: Hofseth Aqua Miljødirektoratet: 21S0629E urn:issn:0046-5070 https://hdl.handle.net/11250/3127240 https://doi.org/10.1111/fwb.14095 cristin:2146754 Freshwater Biology. 2023, 68 (7), 1176-1193. |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright 2023 The Author(s) |
op_doi |
https://doi.org/10.1111/fwb.14095 |
container_title |
Freshwater Biology |
container_volume |
68 |
container_issue |
7 |
container_start_page |
1176 |
op_container_end_page |
1193 |
_version_ |
1799477096687337472 |