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Upstream and downstream passage of migrating adult Atlantic salmon : Remedial measures improve passage performance at a hydropower dam

Nyqvist, Daniel; Nilsson, Anders LU ; Alenäs, I.; Elghagen, J.; Hebrand, M.; Karlsson, S.; Kläppe, S. and Calles, Olle (2017) In Ecological Engineering 102. p.331-343
Abstract

Habitat connectivity is central for life-cycle progression for migrating organisms. Passage of hydropower dams is associated with mortality, delay, and migratory failure for migrating fish, and the need for remedial measures to facilitate passage is widely recognized. Lately, nature-like fishways have been promoted for upstream migrating fish, and low-sloping turbine intake racks for downstream migrating fish, but evaluations of these remedial measures are largely lacking. At Herting hydropower dam in southern Sweden, a technical fishway for upstream migrating salmonids, and a simple bypass entrance/trash gate for downstream migrating fish have been replaced by a large nature-like fishway for up and downstream migrating fish, and a... (More)

Habitat connectivity is central for life-cycle progression for migrating organisms. Passage of hydropower dams is associated with mortality, delay, and migratory failure for migrating fish, and the need for remedial measures to facilitate passage is widely recognized. Lately, nature-like fishways have been promoted for upstream migrating fish, and low-sloping turbine intake racks for downstream migrating fish, but evaluations of these remedial measures are largely lacking. At Herting hydropower dam in southern Sweden, a technical fishway for upstream migrating salmonids, and a simple bypass entrance/trash gate for downstream migrating fish have been replaced by a large nature-like fishway for up and downstream migrating fish, and a low-sloping rack, guiding downstream migrating fish to the bypass entrance, has been installed. In this study, we evaluated these remedial measures for adult Atlantic salmon, spawners and kelts, in a before/after improved remedial measures radio telemetry study. Passage performance was improved for both up- and downstream migrating adult Atlantic salmon after remedial measures. Passage rate increased for fish migrating in both directions, and overall delay as well as overall passage efficiency decreased for upstream migrating fish. After the improved passage solutions almost all tagged fish passed the dam with very little delay. Before modifications, upstream passage performance through the technical fishway was higher at higher temperatures, at day compared to night, and for males compared to females. No such effects were observed for the after-measures nature-like fishway, indicating good passage performance for both sexes under a wide range of environmental conditions. Similarly, for downstream migrating kelts, discharge positively affected passage rate before but not after the fishway modifications. Altogether, our work demonstrates the possibility of coexistence between hydropower and Atlantic salmon in a regulated river.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Denil fishway, Fish passage rate, Kelt, Longitudinal connectivity, Low-sloping intake rack, Nature-like fishway
in
Ecological Engineering
volume
102
pages
13 pages
publisher
Elsevier
external identifiers
  • scopus:85013746014
  • wos:000399623700034
ISSN
0925-8574
DOI
10.1016/j.ecoleng.2017.02.055
language
English
LU publication?
yes
id
f6c045a0-f2c0-4e0c-82ef-ea6c771d88a9
date added to LUP
2017-03-08 08:16:52
date last changed
2017-09-18 11:37:49
@article{f6c045a0-f2c0-4e0c-82ef-ea6c771d88a9,
  abstract     = {<p>Habitat connectivity is central for life-cycle progression for migrating organisms. Passage of hydropower dams is associated with mortality, delay, and migratory failure for migrating fish, and the need for remedial measures to facilitate passage is widely recognized. Lately, nature-like fishways have been promoted for upstream migrating fish, and low-sloping turbine intake racks for downstream migrating fish, but evaluations of these remedial measures are largely lacking. At Herting hydropower dam in southern Sweden, a technical fishway for upstream migrating salmonids, and a simple bypass entrance/trash gate for downstream migrating fish have been replaced by a large nature-like fishway for up and downstream migrating fish, and a low-sloping rack, guiding downstream migrating fish to the bypass entrance, has been installed. In this study, we evaluated these remedial measures for adult Atlantic salmon, spawners and kelts, in a before/after improved remedial measures radio telemetry study. Passage performance was improved for both up- and downstream migrating adult Atlantic salmon after remedial measures. Passage rate increased for fish migrating in both directions, and overall delay as well as overall passage efficiency decreased for upstream migrating fish. After the improved passage solutions almost all tagged fish passed the dam with very little delay. Before modifications, upstream passage performance through the technical fishway was higher at higher temperatures, at day compared to night, and for males compared to females. No such effects were observed for the after-measures nature-like fishway, indicating good passage performance for both sexes under a wide range of environmental conditions. Similarly, for downstream migrating kelts, discharge positively affected passage rate before but not after the fishway modifications. Altogether, our work demonstrates the possibility of coexistence between hydropower and Atlantic salmon in a regulated river.</p>},
  author       = {Nyqvist, Daniel and Nilsson, Anders and Alenäs, I. and Elghagen, J. and Hebrand, M. and Karlsson, S. and Kläppe, S. and Calles, Olle},
  issn         = {0925-8574},
  keyword      = {Denil fishway,Fish passage rate,Kelt,Longitudinal connectivity,Low-sloping intake rack,Nature-like fishway},
  language     = {eng},
  month        = {05},
  pages        = {331--343},
  publisher    = {Elsevier},
  series       = {Ecological Engineering},
  title        = {Upstream and downstream passage of migrating adult Atlantic salmon : Remedial measures improve passage performance at a hydropower dam},
  url          = {http://dx.doi.org/10.1016/j.ecoleng.2017.02.055},
  volume       = {102},
  year         = {2017},
}