Difference between revisions of "Case study:Restoration of spawning grounds for trout in Bjornesfjorden (Hardangervidda)"

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|Project summary=The Bjornesfjord was temporarily lowered in 1959 to provide water for hydroelectric powerplants (Noreverkene) in Norway. This resulted in permanent damage to several spawning grounds for trout, as the original spawning-substrates were removed. This meant that the substrate of the affected spawning areas became dominated by sand and that the areas were no longer suitable for spawning. To compensate for the damage caused to the fish stock in connection with the lowering of water in the fjord, an order was issued for the release of trout. In the period between 2002-2006, LFI Uni Miljø, in collaboration with NLB, Statkraft and NVE, restored spawning areas in the Bjornesfjord. The restoration was carried out by laying gravel in the outlet of Lågaros, in the Nøresundet and Meinsbusundet. These areas had been adversely affected by the lowering of the fjord in 1959.
 
|Project summary=The Bjornesfjord was temporarily lowered in 1959 to provide water for hydroelectric powerplants (Noreverkene) in Norway. This resulted in permanent damage to several spawning grounds for trout, as the original spawning-substrates were removed. This meant that the substrate of the affected spawning areas became dominated by sand and that the areas were no longer suitable for spawning. To compensate for the damage caused to the fish stock in connection with the lowering of water in the fjord, an order was issued for the release of trout. In the period between 2002-2006, LFI Uni Miljø, in collaboration with NLB, Statkraft and NVE, restored spawning areas in the Bjornesfjord. The restoration was carried out by laying gravel in the outlet of Lågaros, in the Nøresundet and Meinsbusundet. These areas had been adversely affected by the lowering of the fjord in 1959.
  
Subsequent surveys in 2007 and 2013 show that the restoration worked as intended, with spawning found each year on the newly established spawning grounds. The measures, therefore, helped to improve spawning conditions towards the natural state that existed before the lowering.
+
Subsequent surveys in 2007 and 2013 show that the restoration worked as intended, with spawning occurring each year on the newly established spawning grounds. The measures, therefore, helped to bring spawning conditions towards the natural state that existed before the lowering.
 
|Monitoring surveys and results=https://uni.no/media/manual_upload/LFI_235.pdf
 
|Monitoring surveys and results=https://uni.no/media/manual_upload/LFI_235.pdf
 
|Lessons learn=The establishment of flow deflectors and the laying of rocks, blocks and uprooted trees in areas with previously low hydromorphological variation, have great potential for the improvement of the aquatic environment and habitats - in this example, fish production increased in the rehabilitated areas.
 
|Lessons learn=The establishment of flow deflectors and the laying of rocks, blocks and uprooted trees in areas with previously low hydromorphological variation, have great potential for the improvement of the aquatic environment and habitats - in this example, fish production increased in the rehabilitated areas.

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Location: 60° 9' 0", 7° 46' 10"
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Project overview

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Status Complete
Project web site
Themes Environmental flows and water resources, Habitat and biodiversity, Hydropower, Hydromorphology
Country Norway
Main contact forename Nils Runar
Main contact surname Sporan
Main contact user ID
Contact organisation Statkraft AS
Contact organisation web site http://www.statkraft.no
Partner organisations Uni Reserch Miljø LFI, Numedals-Laugens Brugseierforening (NLB), The Norwegian Water Resources and Energy Directorate (NVE)
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Project picture

Project summary

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The Bjornesfjord was temporarily lowered in 1959 to provide water for hydroelectric powerplants (Noreverkene) in Norway. This resulted in permanent damage to several spawning grounds for trout, as the original spawning-substrates were removed. This meant that the substrate of the affected spawning areas became dominated by sand and that the areas were no longer suitable for spawning. To compensate for the damage caused to the fish stock in connection with the lowering of water in the fjord, an order was issued for the release of trout. In the period between 2002-2006, LFI Uni Miljø, in collaboration with NLB, Statkraft and NVE, restored spawning areas in the Bjornesfjord. The restoration was carried out by laying gravel in the outlet of Lågaros, in the Nøresundet and Meinsbusundet. These areas had been adversely affected by the lowering of the fjord in 1959.

Subsequent surveys in 2007 and 2013 show that the restoration worked as intended, with spawning occurring each year on the newly established spawning grounds. The measures, therefore, helped to bring spawning conditions towards the natural state that existed before the lowering.

Monitoring surveys and results

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https://uni.no/media/manual_upload/LFI_235.pdf

Lessons learnt

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The establishment of flow deflectors and the laying of rocks, blocks and uprooted trees in areas with previously low hydromorphological variation, have great potential for the improvement of the aquatic environment and habitats - in this example, fish production increased in the rehabilitated areas.

Higher densities of both “yearlings” and older juvenile fish were found in the habitat-improved areas than were found in the control sites.

The flow deflectors led to a better spatial distribution of spawning opportunities for lake trout in the upper part of the Teigdal river.

It could have been advantageous to place more blocks and stones in the riverbed to increase the extent of the measures and thus the quality of the habitat in the habitat-poor areas. An analysis of the total available area in the three habitat-improved areas shows that only 2% of this area had been improved. An increase would further enhance the habitat and lead to a higher fish production.


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Catchment and subcatchment



Site

Name Bjornesfjorden
WFD water body codes 015-418-L (EU-ID:NO015-418-L)
WFD (national) typology LEH32113
WFD water body name Bjornesfjorden
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation Norway - Nasjonalpark
Local/regional site designations National Park
Protected species present No
Invasive species present No
Species of interest Brown trout (Salmo trutta)
Dominant hydrology
Dominant substrate Cobble, Gravel
River corridor land use Natural open water
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started 1999/01/01
Works started
Works completed
Project completed 2013/01/01
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources Statkraft AS

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Hydropower
Hydromorphology
Biology Fish
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Creation of fish spawn nursing places, Introduction of spawning gravels
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish Yes Yes No No Yes Improvement
Invertebrates Yes Yes No No Yes No change

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

Link Description
http://uni.no/media/manual upload/LFI 235.pdf Report
http://www.miljodirektoratet.no/globalassets/publikasjoner/m1051/m1051.pdf Measures Handbook for better physical aquatic environment

Supplementary Information

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