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Atlantic salmon in regulated rivers: Migration, dam passage, and fish behavior
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Hydropower dams block migration routes and disrupt longitudinal connectivity in rivers, thereby posing a threat to migratory fish species. Various fish passage solutions have been implemented to improve connectivity with varying success. A well-functioning passage solution must ensure safe and timely passage routes that are used by a substantial portion of the migrating fish. In this thesis, I report the results from telemetry studies where the behavior and survival of migrating Atlantic salmon spawners, post-spawners and smolts have been evaluated in relation to hydropower dam passage. I evaluate downstream passage performance at dams with no passage solutions in the River Klarälven, and with simple passage solutions in in the Winooski River. In the River Ätran, I study both upstream- and downstream passage performance at a dam with sophisticated passage solutions based on the best available technology. In addition, I have studied the survival and behavior of post-spawners and hatchery-released smolts.

A substantial portion of the spawners survived spawning and initiated downstream migration. Most males migrated downstream in autumn following spawning, whereas females tended to stay in the river until spring. For hatchery-reared smolts, early release was associated with faster initiation of migration and higher survival compared to late release. Multiple dam passage resulted in high mortality for both smolts and kelts. For smolts, dam passage, even with simple passage solutions, was associated with substantial delay and mortality. High spill levels were linked to high survival and short delay for downstream migrating salmon. The best available passage solution, which consisted of a nature-like fishway and a low sloping intake rack to guide fish to a bypass, resulted in rapid passage of a large portion of the adult migrants.

Abstract [en]

Hydropower dams block migration routes, thereby posing a threat to migratory fish species. Fishways and other fish passage solutions may aid fish to pass hydropower dams. A functional fish passage solution, however, must ensure safe and timely passage for a substantial portion of the migrating fish. In this thesis, I focus on downstream passage and evaluate the behavior and survival of migrating Atlantic salmon in relation to dams in systems with (1) no fish passage solutions (2) simple passage solutions (3) best available passage solutions. In addition, I studied the survival and behavior of post-spawners and hatchery-released smolts.

 

A large portion of the spawners survived spawning and initiated downstream migration. For hatchery-reared smolts, early release was associated with faster initiation of migration and higher survival compared to late release. Multiple dam passage resulted in high mortality, and high spill levels were linked to high survival and short delay for downstream migrating salmon. For smolts, dam passage, even with simple passage solutions, was associated with substantial delay and mortality. Rapid passage of a large portion of the migrating adult salmon was achieved using best available passage solutions.  

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2016. , 41 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 42
Keyword [en]
fish migration; fish passage; downstream migration; kelt; smolt
National Category
Biological Sciences
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-46903ISBN: 978-91-7063-725-4OAI: oai:DiVA.org:kau-46903DiVA: diva2:1038779
Public defence
2016-12-09, Nyquistsalen 9C 203, Universitetsgatan 2, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2016-11-15 Created: 2016-10-19 Last updated: 2016-12-07Bibliographically approved
List of papers
1. Post-Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning?
Open this publication in new window or tab >>Post-Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning?
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2015 (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 5, 1008-1017 p.Article in journal (Refereed) Published
Abstract [en]

Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, relatively little is known about this phase of the life history for anadromous populations, and nothing has been reported for landlocked populations. Here, we studied post-spawning behaviour and survival of landlocked Atlantic salmon in relation to downstream dam passage in the River KlarÀlven, Sweden. Eight hydropower stations separate the feeding grounds in Lake VÀnern from the spawning grounds in the River KlarÀlven, and no measures to facilitate downstream migration are present in the river. Forty-nine percent of the salmon survived spawning and initiated downstream migration. Females and small fish had higher post-spawning survival than males and large fish. The post-spawners migrated downstream in autumn and spring and remained relatively inactive in the river during winter. Downstream migration speed in the free flowing part of the river was highly variable with a median of 9.30km/day. Most fish passed the first hydropower station via upward-opening spill gates after a median residence time in the forebay of 25min. However, no tagged fish survived passage of all eight hydropower stations to reach Lake VÀnern. This result underscores the need for remedial measures to increase the survival of downstream migrating kelts.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keyword
migration; kelt; multiple dam passage; telemetry; hydropower; gender difference
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-42458 (URN)10.1002/rra.2926 (DOI)000378715500018 ()2-s2.0-84931843504 (ScopusID)
Available from: 2016-05-23 Created: 2016-05-23 Last updated: 2016-12-07Bibliographically approved
2. Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam
Open this publication in new window or tab >>Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam
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2016 (English)In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633Article in journal (Refereed) Epub ahead of print
Abstract [en]

Passage of fish through hydropower dams is associated with mortality, delay, increased energy expenditure and migratory failure for migrating fish and the need for remedial measures for both upstream and downstream migration is widely recognised. A functional fish passage must ensure safe and timely passage routes that a substantial portion of migrating fish will use. Passage solutions must address not only the number or percentage of fish that successfully pass a barrier, but also the time it takes to pass. Here, we used radiotelemetry to study the functionality of a fish bypass for downstream-migrating wild-caught and hatchery-released Atlantic salmon smolts. We used time-to-event analysis to model the influence of fish characteristics and environmental variables on the rates of a series of events associated with dam passage. Among the modelled events were approach rate to the bypass entry zone, retention rates in both the forebay and the entry zone and passage rates. Despite repeated attempts, only 65% of the tagged fish present in the forebay passed the dam. Fish passed via the bypass (33%), via spill (18%) and via turbines (15%). Discharge was positively related to approach, passage and retention rates. We did not detect any differences between wild and hatchery fish. Even though individual fish visited the forebay and the entry zone on multiple occasions, most fish passed during the first exposures to these zones. This study underscores the importance of timeliness to passage success and the usefulness of time-to-event analysis for understanding factors governing passage performance.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016
Keyword
downstream passage, fish passage, landlocked salmon, Salmo salar, smolt migration, nedströmspassage, fiskpassage, smolt, lax
National Category
Natural Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-46897 (URN)10.1111/eff.12318 (DOI)
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2016-12-07Bibliographically approved
3. Migration and multiple dam passage by Atlantic salmon smolts
Open this publication in new window or tab >>Migration and multiple dam passage by Atlantic salmon smolts
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(English)Manuscript (preprint) (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:kau:diva-46900 (URN)
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2016-12-07
4. Two-way hydropower dam passage of migrating adult Atlantic salmon
Open this publication in new window or tab >>Two-way hydropower dam passage of migrating adult Atlantic salmon
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(English)Manuscript (preprint) (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:kau:diva-46901 (URN)
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2016-10-28
5. Hydropower dam approach and passage by Atlantic salmon kelts
Open this publication in new window or tab >>Hydropower dam approach and passage by Atlantic salmon kelts
(English)Manuscript (preprint) (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:kau:diva-46902 (URN)
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2016-12-07

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