Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Conservation of landlocked Atlantic salmon in a regulated river: Behaviour of migratory spawners and juveniles
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).ORCID iD: 0000-0002-9683-8080
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Hydropower dams represent one of the major threats to river ecosystems today. The dams block migratory routes in many rivers, which is problematic for migratory fish species. Trap-and-transport may be an alternative to fish passage solutions, as a strategy to compensate for lost river connectivity. Stocking of hatchery fish is another mitigating measure often used to compensate for reduced yields in fisheries, but also as supportive breeders in declining populations.

 

In this thesis, I report the results from radio-telemetry studies where the behavior of migrating Atlantic salmon spawners has been investigated in a regulated river. I also studied the function and success of using hatchery fish as supportive breeders and if there are any effects of migratory timing on migratory success. Further, I evaluated upstream passage performance by Atlantic salmon and brown trout at fishways in rivers Klarälven, Sweden and Gudbrandslågen, Norway. The goal was to determine if prior fishway experience had an effect on passage success. I identified three problems associated with the current river management, namely the high incidence of fallbacks among the early migrating salmon, the negative effects of high river flow and prior experience on fishway efficacy and that the use of hatchery-reared fish as supportive breeders have little, if any, positive effect on reproduction. Finally, I examined the competitive interactions that may occur when reintroducing Atlantic salmon to areas with native grayling and brown trout. I found no evidence of Atlantic salmon affecting grayling or brown trout. Instead, Atlantic salmon were dominated by the other two species, which indicates that reintroduction of salmon may not be successful, especially if habitat diversity is constrained.

 

Conservation and management of migratory salmonids requires an understanding of their ecology and life-histories. In the regulated river Klarälven, populations of landlocked Atlantic salmon and migratory brown trout have declined due to river exploitation. The results presented in this thesis originate from concerns regarding salmonid conservation in regulated rivers, with a focus on the difficulties migratory spawners may face in these altered environments.

Abstract [en]

In this thesis, I report the results from radio-telemetry studies where the behavior and success of migrating Atlantic salmon (Salmo salar) spawners has been investigated in a regulated river. I have also studied the function of using hatchery fish as supportive breeders and evaluated the upstream passage performance by Atlantic salmon and brown trout (Salmo trutta) at fishways in the River Klarälven, Sweden and Gudbrandslågen, Norway.

I identified three problems associated with management in a regulated river, namely the high incidence of fallbacks among the early migrating salmon, the negative effects of high river flow and prior experience on fishway efficacy and that the use of hatchery-reared fish as supportive breeders have little, if any, positive effect on reproduction.

Finally, I examined the competitive interactions that may occur when reintroducing Atlantic salmon to areas with native grayling (Thymallus thymallus) and brown trout.

Conservation and management of migratory salmonids requires an understanding of ecology and life-histories. The results presented in this thesis originate from concerns regarding salmonid conservation in regulated rivers, with a focus on the difficulties migratory spawners may face in these altered environments. The results of my research can be applied to other regulated systems, particularly those with trap and transport solutions.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2019. , p. 51
Series
Karlstad University Studies, ISSN 1403-8099 ; 2019:7
Keywords [en]
Atlantic salmon, conservation, migration, spawning, hydropower, competition, juveniles, brown trout, hatchery reared, fallback, delay
National Category
Biological Sciences
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-71333ISBN: 978-91-7867-002-4 (print)ISBN: 978-91-7867-007-9 (electronic)OAI: oai:DiVA.org:kau-71333DiVA, id: diva2:1291171
Public defence
2019-04-12, Sjöströmssalen 1B309, Karlstad Universitet, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2019-03-22 Created: 2019-02-22 Last updated: 2019-03-22Bibliographically approved
List of papers
1. Spawning migration of wild and supplementary stocked landlocked atlantic salmon (Salmo Salar)
Open this publication in new window or tab >>Spawning migration of wild and supplementary stocked landlocked atlantic salmon (Salmo Salar)
Show others...
2016 (English)In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 32, no 3, p. 383-389Article in journal (Refereed) Published
Abstract [en]

Upstream migration by adult salmonids is impeded by dams in many regulated rivers, as is the case for landlocked Atlantic salmon, Salmo salar, in the River Klarälven, Sweden. There, the salmon cannot reach the spawning grounds due to the presence of eight dams. Hence, hatchery-reared smolts are released downstream of the dams, and upstream migrating spawners are caught in a trap at the lowermost dam before transported by truck to the spawning grounds past the dams. To identify the spawning grounds and compare the behavior of wild and hatchery-reared Atlantic salmon during upstream migration and spawning, 34 wild and 28 hatchery-reared, radio-tagged Atlantic salmon were followed during their spawning migration from August to October 2011. Half (50%) of the hatchery fish, but only 11,8% of the wild fish ended up as fallbacks, i.e. they migrated past the first downstream power station, and did not spawn. A significantly higher proportion (21.4%) of hatchery- reared salmon moved in an erratic way, with several up and down stream movements, when compared to the wild salmon (5.9%). When looking at the salmon that stayed in the river (exc. fallbacks), wild individuals exhibited a holding behavior (little or no movements before presumed spawning) more often (86.7%) than the reared ones (50%). The wild salmon also held position (and presumably spawned) for longer time (25.4 days) than the reared salmon (16.1 days). Reared salmon held position, on average, 10 km further upstream than wild salmon, passing the presumed best-quality spawning habitat. The migration speed (average 17.4 km/day) between two logger stations did not differ between wild and reared fish or between sexes. Our results suggest that the reproductive success of hatchery-reared Atlantic salmon is relatively low and their capacity as supplementary spawners to the wild population in the Klarälven, is probably small.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keywords
Salmo salar, supplementary stocking, spawning, migratory behaviour, landlocked, telemetry
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-35930 (URN)10.1002/rra.2870 (DOI)000372354700014 ()
Available from: 2015-04-29 Created: 2015-04-29 Last updated: 2019-02-22Bibliographically approved
2. The Migratory Behaviour and Fallback Rate of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: does Timing Matter?
Open this publication in new window or tab >>The Migratory Behaviour and Fallback Rate of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: does Timing Matter?
Show others...
2016 (English)In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 32, no 6, p. 1402-1409Article in journal (Refereed) Published
Abstract [en]

The behavior of early (June-July) and late (August-September) migrating, adult Atlantic salmon, in The River Klaralven, Sweden, was analyzed using radio telemetry. River Klaralven is a regulated river without functioning fishways, instead upstream migrating salmon are trapped and trucked past eight hydropower plants before released back to the river. We distinguished two parts of the spawning migration, that is, one part being the migration from the place where the fish was released to the spawning grounds. The other part was a holding phase on the spawning grounds with little or no movements before spawning. The late salmon spent less of their total time on holding, 36.2%, and more on migration, 63.8%, compared with early migrating salmon, which distributed their time rather evenly between migration, 47.5%, and holding, 52.5%. In total, early salmon used 30% more time migrating and 156% more time holding than late salmon. Some Atlantic salmon (Salmo salar) fell back over the hydropower plant after release and got excluded from spawning. The fallback rates of transported, tagged spawners were higher in the early than in the late group in both years. The fallback rate in 2012 was 42.8% of the early group and 15.1% in the late. In 2013, there were 51.7 % fallbacks in the early group and 3.4% in the late. The salmon fell back on average 9days after being released in 2012 and 16days in 2013. A high mean daily discharge on the day of release increased the probability of becoming a fallback. Copyright (c) 2016 John Wiley & Sons, Ltd.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keywords
Atlantic Salmon, upstream migration, fallback, spawning, behaviour, timing
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-44678 (URN)10.1002/rra.3007 (DOI)000379952900023 ()
Available from: 2016-08-12 Created: 2016-08-12 Last updated: 2019-02-22Bibliographically approved
3. Upstream fishway performance by Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) spawners at complex hydropower dams –is prior experience a success criterion?
Open this publication in new window or tab >>Upstream fishway performance by Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) spawners at complex hydropower dams –is prior experience a success criterion?
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Passage of hydropower plants by upstream-migrating salmonid spawners is associated with increased mortality, delays, injuries and reduced migration success, and consequently the need for a more comprehensive understanding of fish behavior downstream of dams is widely recognized. Studies of passage typically involve tagging fish, and in many cases, the fish used in these studies are caught in the fishways, and hence have prior experience negotiating them. In this study, we studied fishway passage of tagged landlocked Atlantic salmon (Salmo salar) in the River Klarälven, Sweden and brown trout (Salmo trutta) in the River Gudbrandslågen, Norway, and the influence of prior experience on passage success in 2012 and 2013. In the River Klarälven, fishway efficacy varied from 18 (2012) to 88% (2013). Most salmon (81%) entered the fishway trap on days without spill, and salmon moved from the turbine area to the spill zone when there was spill, with small individuals showing a stronger reaction than large fish. Analysis of fish with and without prior trap experience showed that a higher percentage of the “naïve” fish (70% of salmon and 43% of the trout) entered the fishway traps than the “experienced” ones (25% of the salmon and 15 % of the trout). Delays for fish that entered the trap ranged from 3-70 days for salmon and 2-47 days for trout, and there was no difference in median delay between naïve and experienced fish for each species. Manual positioning of radio-tagged salmon revealed that 11% of the naïve fish and 50% of the experienced fish ceased migration after tagging and release. In addition, a greater percentage of the salmon that were captured, marked and released in the lake attempted to enter the fishway (70%) than lake-caught salmon that were also transported 10km to the stream before release (33%). The data based on manual positioning and lake caught salmon indicate that differences in behavior of naïve and experienced individuals are likely stress-related. Moreover, our results suggest that estimates of fishway efficacy using fish with prior fishway experience may be biased, and based on our study, efficacy is underestimated.

Keywords
Atlantic salmon, brown trout, migration, spawners, spawning, fishways, fish passage solutions, delay, hydropower
National Category
Natural Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-71325 (URN)
Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2019-02-22
4. Reintroducing Atlantic salmon to once native areas: Competition between Atlantic salmon, brown trout and grayling
Open this publication in new window or tab >>Reintroducing Atlantic salmon to once native areas: Competition between Atlantic salmon, brown trout and grayling
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Worldwide declines in salmonid populations have generated major interest in conservation and restoration of wild populations and riverine habitats. Plans to re-introduce species to rivers where they previously occurred raises questions as to their potential impact on these systems after so many years. In the River Klarälven, Atlantic salmon (Salmo salar) has been extinct from the upper reaches of its former distribution for more than 50 years due to the construction of hydropower dams. Here we study competitive interactions between Atlantic salmon and two other salmonids, grayling (Thymallus thymallus) and brown trout (Salmo trutta), that presently occur in the upper reaches of the river. We examine foraging rates, aggression and activity of juvenile Atlantic salmon, grayling and brown trout in allopatry at three different densities and in sympatry with one or both potential competitors in laboratory flumes. We found that Atlantic salmon captured prey less frequently in the presence of brown trout and grayling, whereas grayling and brown trout affected each other, but were unaffected by Atlantic salmon. Rates of aggression initiated by salmonids in allopatry versus sympatry revealed differences between fish species, with grayling being the most aggressive and salmon the least. There was also a difference in activity, i.e. time spent cruising or holding position, between the species, with grayling being the most active and salmon the least. These results suggest that re-introduction of Atlantic salmon probably will have little impact on grayling and brown trout, whereas high densities of grayling and brown trout could affect the success of re-introducing Atlantic salmon.

National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-71326 (URN)
Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2019-02-25Bibliographically approved

Open Access in DiVA

fulltext(2890 kB)80 downloads
File information
File name FULLTEXT02.pdfFile size 2890 kBChecksum SHA-512
2b06651e6c10b75d927193a9012d5056a51fc2b321d137d8d7b0b14fcabbd9178bc380f5355387aa4b5dc54ca7853e1a396408c1f841dadd1ace9dbf19d58cdd
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Hagelin, Anna
By organisation
Department of Environmental and Life Sciences (from 2013)
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 80 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 139 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf