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Downstream passage of diadromous fish in Swedish rivers
Karlstad University, Faculty of Social and Life Sciences, Department of Biology.ORCID iD: 0000-0002-8738-8815
2009 (English)Conference paper, Published paper (Refereed)
Abstract

Downstream passage problems for diadromous fish are rarely addressed in regulated rivers in northern Europe. Some attempts to decrease the mortality among downstream moving fish are now tested in southern Sweden, ranging from the use of trash gates to

testing of low-sloped fine-spaced racks. This presentation describes the efficiency of two

such measures at hydroelectric facilities in the River Ätran. The targeted species were Atlantic salmon, anadromous brown trout and European eel. Smolt (N=66, 2007), kelt (N=20, 2007) and silver eels (N=170, 2007-2008) were radio-tagged and tracked in

passing the facilities.



An open trash gate proved to have a very low efficiency for smolt (7%) and most individuals passed through the racks and turbines. The efficiency was intermediate for kelt (40%) and several individuals died on the trash racks or remained upstream until the

end of the study. The route seeking time was limited for smolts, but substantial for kelts. Since no control groups were used the extent of the delays could not be quantified. The overall passage success was 50% for kelts and 85% for smolts, illustrating the need for a more efficient measure for kelts in particular.



The passage for silvers eels of the two lower most hydroelectric plants (HEPs) in the River Ätran revealed a 28% passage success at HEP 2 (N=50), with a 23,5 m head and Francis turbines. The corresponding success for the control group released downstream of

the HEP was 92% (N=50). The following year the old rack (20 mm / 43°) was replaced by a new rack (18 mm / 35°) with exits at the surface. With the new rack in place 80% of the eels released upstream were successfully diverted and caught, resulting in a total

success of 90% (compared to 28% with the old rack). The success at HEP 1 was 76% (N=58), but no individuals entered the open trash gate. The success rate was somewhat uncertain because of the short distance to sea and the possibility for injured (but not dead) individuals to reach sea but not surviving in the long run

Place, publisher, year, edition, pages
Umeå, 2009.
National Category
Biological Sciences
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-11182OAI: oai:DiVA.org:kau-11182DiVA, id: diva2:494751
Conference
8th Conference on Fish Telemetry held in Europe
Projects
Fri fiskvandring i Ätran - Falkenbergs kommunAvailable from: 2012-02-08 Created: 2012-02-08 Last updated: 2019-07-12Bibliographically approved

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CiteExportLink to record
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