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Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.ORCID iD: 0000-0002-3098-0594
Karlstad University, Faculty of Social and Life Sciences, Department of Biology.ORCID iD: 0000-0002-3191-7140
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.ORCID iD: 0000-0002-8738-8815
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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 [en]
downstream passage, fish passage, landlocked salmon, Salmo salar, smolt migration
Keyword [sv]
nedströmspassage, fiskpassage, smolt, lax
National Category
Natural Sciences
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-46897DOI: 10.1111/eff.12318OAI: oai:DiVA.org:kau-46897DiVA: diva2:1038769
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2016-12-07Bibliographically approved
In thesis
1. Atlantic salmon in regulated rivers: Migration, dam passage, and fish behavior
Open this publication in new window or tab >>Atlantic salmon in regulated rivers: Migration, dam passage, and fish behavior
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
fish migration; fish passage; downstream migration; kelt; smolt
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-46903 (URN)978-91-7063-725-4 (ISBN)
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

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Publisher's full texthttp://onlinelibrary.wiley.com/doi/10.1111/eff.12318/full

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Nyqvist, DanielGreenberg, LarryCalles, OlleBergman, Eva
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