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Effects of feeding regimes and early maturation on migratory behaviour of landlocked hatchery-reared Atlantic salmon Salmo salar smolts
Karlstad University, Faculty of Social and Life Sciences, Department of Biology. (NRRV - Naturresurs Rinnande Vatten)
Karlstad University, Faculty of Social and Life Sciences, Department of Biology.ORCID iD: 0000-0003-2220-1615
Karlstad University, Faculty of Social and Life Sciences. (NRRV - Naturresurs Rinnande Vatten)
Karlstad University, Faculty of Social and Life Sciences, Department of Biology. (NRRV - Naturresurs Rinnande Vatten)ORCID iD: 0000-0002-3191-7140
2014 (English)In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 85, no 4, 1060-1073 p.Article in journal (Refereed) Published
Abstract [en]

The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature males, which had matured the previous autumn, were also tagged and released. To monitor migration of the fish, acoustic receivers were deployed along the migratory route. The proportion of S. salar that reached Lake Vänern was significantly greater for fish fed fat-reduced feed than for fish given rations with higher fat content, regardless of ration size. Fish from the early mature male group remained in the river to a greater extent than fish from the three feeding regimes. Smolt status (degree of silvering), as visually assessed, did not differ among the feeding regime groups, and moreover, fully-silvered fish, regardless of feeding regime, migrated faster and had a greater migration success than fish with less developed smolt characteristics. Also, successful migrants had a lower condition factor than unsuccessful ones. These results indicate that the migration success of hatchery-reared S. smolts released to the wild can be enhanced by relatively simple changes in feeding regimes and by matching stocking time with smolt development.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2014. Vol. 85, no 4, 1060-1073 p.
Keyword [en]
acoustic telemetry, fat-reduced feed, fisheries management, migration success, smolt status, stocking
National Category
Biological Sciences Ecology
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-34005DOI: 10.1111/jfb.12522ISI: 000342828400005PubMedID: 25263187OAI: oai:DiVA.org:kau-34005DiVA: diva2:752506
Note

The article was part of J. Norrgårds thesis and was still in manuscript form when the thesis was published.

Available from: 2014-10-04 Created: 2014-10-04 Last updated: 2016-08-16Bibliographically approved
In thesis
1. Migration and quality of landlocked Atlantic salmon smolt: Implications for conservation and management
Open this publication in new window or tab >>Migration and quality of landlocked Atlantic salmon smolt: Implications for conservation and management
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Atlantic salmon Salmo salar has a complex life cycle, including long migrations and habitat shifts for both juveniles and adults. As such, salmon populations are vulnerable to habitat degradation and fragmentation along their migratory routes. This makes management and conservation a complex task requiring knowledge of salmon ecology at different temporal and spatial scales. In this thesis I highlight the use of a holistic life-history based approach in the conservation and management of wild and hatchery-reared salmon in regulated rivers and lakes.

Small populations of wild-reproducing landlocked salmon and trout Salmo trutta exist in the regulated River Klarälven, Sweden. Since the 1930s, transportation of adult spawners upstream of eight dams has given the fish access to spawning grounds. The number of returning wild spawners became critically low in the 1960s, but stocking of hatchery smolts resulted in an increase in spawners that continues today. My data show that wild smolt may suffer high mortality due to multiple dam passages. To ensure viable populations of wild populations, future management should include both up- and downstream solutions that ensure connectivity in the system.

The recreational and commercial salmonid fishery are maintained by compensatory stockings, yielding annual catches of about 75 tons, and a river return rate of hatchery fish of about 1%. As a large portion of the stocked smolts does not survive downstream migration to the lake, there has been discussion about the quality of the stocked smolt and about stocking strategies. Based on my studies, producing hatchery smolts more closely resembling wild-born conspecifics should result in reduced loss rates. I suggest changes in the hatchery and stocking procedures to increase the survival of stocked smolts. The results of my research should be applicable to other regulated systems, particularly those with mixed stocks of wild and hatchery salmonid populations.

Abstract [en]

Atlantic salmon Salmo salar has a complex life cycle, including long migrations and habitat shifts for both juveniles and adults. As such, salmon populations are vulnerable to habitat degradation and fragmentation along their migratory routes, which make management and conservation a complex task requiring knowledge of salmon ecology at different temporal and spatial scales. In this thesis, I highlight the use of a holistic approach in the conservation and management of wild and hatchery-reared salmon in regulated rivers and lakes.

Small populations of wild-reproducing landlocked salmon and trout Salmo trutta exist in the regulated River Klarälven, Sweden. Since 1930, transportation of adult spawners upstream of eight dams has been done to give the fish access to the spawning grounds. My data indicate that a large proportion of the wild smolts are lost due to multiple dam passages, and future management should include both up- and downstream solutions, ensuring connectivity in the system. The fishery in Klarälven and Lake Vänern is maintained by compensatory stockings, yielding catches of about 75 metric tons and a river return rate of stocked fish of about 1%. I suggest changes in the hatchery and stocking procedures to increase the survival of stocked smolts.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2014. 43 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2014:29
Keyword
acoustic telemetry, hatchery, life history, migration mortality, regulated rivers, Salmo salar, salmon, smolt, trout
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-31980 (URN)978-91-7063-561-8 (ISBN)
Public defence
2014-06-05, Erlandersalen, Universitetsgatan 2, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2014-05-15 Created: 2014-04-25 Last updated: 2016-08-16Bibliographically approved

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