Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del
The expansion of hydroelectric power has negatively affected the Baltic stock of Atlantic salmon (Salmo salar L.). To enable spawning migration of salmon in flow controlled rivers with intact wild stocks, bypass channels and resting pools with smaller flows are constructed to help salmonids in their...
| Autor principal: | |
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| Formato: | H2 |
| Lenguaje: | sueco Inglés |
| Publicado: |
SLU/Dept. of Wildlife, Fish and Environmental Studies
2015
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| Materias: |
| _version_ | 1855571390159126528 |
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| author | Johansson, Joakim |
| author_browse | Johansson, Joakim |
| author_facet | Johansson, Joakim |
| author_sort | Johansson, Joakim |
| collection | Epsilon Archive for Student Projects |
| description | The expansion of hydroelectric power has negatively affected the Baltic stock of Atlantic salmon (Salmo salar L.). To enable spawning migration of salmon in flow controlled rivers with intact wild stocks, bypass channels and resting pools with smaller flows are constructed to help salmonids in their migration upstream. Some of these restoration actions to help migrating fish are seen in the old river bed in the lower part of river Umeälven where this study was undertaken. Previous research indicates a large loss of potential spawning salmon due to problematic migration routes and slow migration through the old river bed. These migratory problems are assumed to limit the population growth of salmon in the river. This study describes the Baltic salmon migration through the old river bed, from the confluence area to the fish ladder downstream of the dam in Norrfors, when they pass man made constructions in the river aimed to help them upstream. In the summer of 2013 (June-July ) 148 salmon (60-116 cm) was tagged with radiotransmitters at the mouth of river Umeälven, and followed on their upstream migration in the old river bed. I focussed on how an increase and change in flow regimes (by changing the spill flow) affected the salmon migration behavior on this section. The restoration of the new pool area in Baggböle rapids enabled salmon to reside in the area and not immediately return downstream due to a change in the spill flow. 99 % of all salmons from the confluence area was registered at some time in Baggböle. A higher spill flow attracted salmon into the old river bed to reach a constructed holding pool, while lower flow attracted salmon to swim past the top of Baggböle rapids. Ninety percent of the salmons that entered the study site left the confluence area or entered the Baggböle rapids in high flow. Subsequently, 70 % swam upstream from Baggböle in low flow. The passage past Kungsmo has become faster and with higher success since the restoration of this site, but spill flow, or flow changes, could not be observed to be important for the fish to pass this stretch. The overall results of the upstream migration through the old river bed from this year are better than in previous year’s studies. Eighty five percent of the salmons made it from the confluence area up to the bottom of the fish ladder in Stornorrfors. This shows that regulated spill changes together with man made constructions can highly affect salmon migration in regulated rivers positively. |
| format | H2 |
| id | RepoSLU8672 |
| institution | Swedish University of Agricultural Sciences |
| language | swe Inglés |
| publishDate | 2015 |
| publishDateSort | 2015 |
| publisher | SLU/Dept. of Wildlife, Fish and Environmental Studies |
| publisherStr | SLU/Dept. of Wildlife, Fish and Environmental Studies |
| record_format | eprints |
| spelling | RepoSLU86722015-12-14T10:12:02Z Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del The upstream migration of Atlantic Salmon in the restored and flow regulated lower part of Umeälven Johansson, Joakim Atlantic Salmon migration telemetry flow regime Umeälven The expansion of hydroelectric power has negatively affected the Baltic stock of Atlantic salmon (Salmo salar L.). To enable spawning migration of salmon in flow controlled rivers with intact wild stocks, bypass channels and resting pools with smaller flows are constructed to help salmonids in their migration upstream. Some of these restoration actions to help migrating fish are seen in the old river bed in the lower part of river Umeälven where this study was undertaken. Previous research indicates a large loss of potential spawning salmon due to problematic migration routes and slow migration through the old river bed. These migratory problems are assumed to limit the population growth of salmon in the river. This study describes the Baltic salmon migration through the old river bed, from the confluence area to the fish ladder downstream of the dam in Norrfors, when they pass man made constructions in the river aimed to help them upstream. In the summer of 2013 (June-July ) 148 salmon (60-116 cm) was tagged with radiotransmitters at the mouth of river Umeälven, and followed on their upstream migration in the old river bed. I focussed on how an increase and change in flow regimes (by changing the spill flow) affected the salmon migration behavior on this section. The restoration of the new pool area in Baggböle rapids enabled salmon to reside in the area and not immediately return downstream due to a change in the spill flow. 99 % of all salmons from the confluence area was registered at some time in Baggböle. A higher spill flow attracted salmon into the old river bed to reach a constructed holding pool, while lower flow attracted salmon to swim past the top of Baggböle rapids. Ninety percent of the salmons that entered the study site left the confluence area or entered the Baggböle rapids in high flow. Subsequently, 70 % swam upstream from Baggböle in low flow. The passage past Kungsmo has become faster and with higher success since the restoration of this site, but spill flow, or flow changes, could not be observed to be important for the fish to pass this stretch. The overall results of the upstream migration through the old river bed from this year are better than in previous year’s studies. Eighty five percent of the salmons made it from the confluence area up to the bottom of the fish ladder in Stornorrfors. This shows that regulated spill changes together with man made constructions can highly affect salmon migration in regulated rivers positively. Utbyggnaden av vattenkraftverk har påverkat den baltiska populationen av atlantlax (Salmo salar L.) negativt. För att möjliggöra för laxarnas lekvandring finns emellertid bypasskanaler (omlöp) med mindre flöden förbi dessa hinder. Ett sådant exempel är gamla älvfåran i nedre delen av Umeälven. Tidigare forskning visar på en stor förlust av lekmogen lax i området p.g.a. svåra vandringsvägar samt lång vandringstid genom gamla älvfåran för att nå fisktrappan ca 8 km uppströms så att de kan nå sina lekområden i Umeälvens största bidlöde Vindelälven. De svåra uppvandringsförhållanden i gamla älvfåran begränsar populationen av lax i Vindelälven. Den här studien beskriver östersjölaxens vandring genom gamla älvfåran, från sammanflödesområdet till fisktrappan nedströms dammluckorna i Norrfors, Umeälven. Under sommaren (juni-juli) 2013 radiomärktes 148 laxar (60-116 cm) vid Umeälvens mynning och deras uppströmsvandring i gamla älvfåran studerades. Fokus riktades mot att analysera hur en ökning och sänkning av spillflödet inverkar på laxens vandringsbeteende på denna sträcka. En andra delfråga låg i att studera effekten av två ombyggnationer av problematiska forspartier längs samma sträcka. I Baggböleforsen har en pool skapats och i Kungsmofallet har forsen delats upp i fler sektioner, likt en stor trappa. Restaureringen av nytt poolområde i Baggböleforsen möjliggjorde att laxen kunde uppehålla sig i området och att den inte vandrade nedströms på grund av flödesändringen eller spillflödet. Nittionio procent av laxen i sammflödet registrerades någon gång upp i Baggböle. Ett högre flöde lockade in laxen i gamla älvfåran medan lägre flöde attraherade laxen att simma förbi övre delen av Baggböleforsen. Nittio procent av laxen i sammanflödet, simmade uppströms eller kom till Baggbölepoolen vid högt flöde. Av dessa simmade 70% vidare vid lågt flöde. Passagen förbi Kungsmo har blivit bättre sedan ombyggnationen men spillflödet eller flödesförändringarna betydelse förbi denna sträcka har liten betydelse. Årets uppvandringsresultat genom gamla älvfåran är bättre än i tidigare år studier. 85 % av alla laxar i sammanflödet tog sig upp till fisktrappan i Stornorrfors. Denna studie visar att förändrat spillflöde och mänskligt byggda konstruktioner till stor del kan påverka laxvandring i regulerade älvar positivt. SLU/Dept. of Wildlife, Fish and Environmental Studies 2015 H2 swe eng https://stud.epsilon.slu.se/8672/ |
| spellingShingle | Atlantic Salmon migration telemetry flow regime Umeälven Johansson, Joakim Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del |
| title | Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del |
| title_full | Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del |
| title_fullStr | Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del |
| title_full_unstemmed | Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del |
| title_short | Laxens uppströmsvandring i den restaurerade och flödesreglerande Umeälvens nedre del |
| title_sort | laxens uppströmsvandring i den restaurerade och flödesreglerande umeälvens nedre del |
| topic | Atlantic Salmon migration telemetry flow regime Umeälven |