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dc.contributor.authorBøhn, Thomas
dc.contributor.authorGjelland, Karl Øystein
dc.contributor.authorSerra-Llinares, Rosa Maria
dc.contributor.authorFinstad, Bengt
dc.contributor.authorPrimicerio, Raul
dc.contributor.authorNilsen, Rune
dc.contributor.authorKarlsen, Ørjan
dc.contributor.authorSandvik, Anne Dagrun
dc.contributor.authorSkilbrei, Ove Tommy
dc.contributor.authorElvik, Kristine Marit Schrøder
dc.contributor.authorSkaala, Øystein
dc.contributor.authorBjørn, Pål Arne
dc.description.abstract1. Atlantic salmon in aquaculture act as reservoir hosts and vectors of parasites like salmon lice and this parasite is shown to harm wild salmonid populations. 2. In this study, n = 29,817 tagged Atlantic salmon were studied in four release trials. Half of the released fish were given prophylactic treatment against lice, the other half represented sham control fish. We used a nested design comparing years with low and high lice density and seasonal dynamics in infestation pressure. The released Atlantic salmon thus experienced highly variable lice infestation pressures, which we linked to survival and growth in returning fish. The fish were released in a protected ‘National Salmon Fjord’ and n = 559 Atlantic salmon were recaptured after spending 1–4 years at sea. 3. In most experimental groups 1%–2.5% of the fish were recaptured at return. However, survival of unprotected fish was extremely low for the trial released at the highest density of lice: only 0.03% of these Atlantic salmon returned to the river, compared to 1.86% in the protected group. 4. Synthesis and applications. We document that high lice density can cause more than 50 times higher mortality risk in Atlantic salmon on their sea migration, even in a fjord with protected status. Fine-tuned and hard-to-predict year-to-year differences in timing, both for the wild smolt migration and the population build-up of lice released from aquaculture, means life or death to wild salmon. Management actions such as spatial segregation of farmed fish and lice (e.g. closed farm pens), and/or moving farms away from vulnerable habitats for wild salmonids (fjords and coastal areas), may be needed to ensure sustainable coexistence of wild and farmed Atlantic salmon.en_US
dc.rightsNavngivelse 4.0 Internasjonal*
dc.subjectaquaculture, Atlantic salmon, management, parasite-induced mortality, randomized controlled trials, salmon lice, wild and farmed fish interactionsen_US
dc.subjectAtlantic salmonen_US
dc.subjectparasite-induced mortalityen_US
dc.subjectrandomized controlled trialsen_US
dc.subjectsalmon liceen_US
dc.subjectwild and farmed fish interactionsen_US
dc.titleTiming is everything: Survival of Atlantic salmon Salmo salar postsmolts during events of high salmon lice densitiesen_US
dc.typeJournal articleen_US
dc.rights.holder© 2020 The Authors.en_US
dc.subject.nsiVDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480en_US
dc.source.journalJournal of Applied Ecologyen_US

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Navngivelse 4.0 Internasjonal
Except where otherwise noted, this item's license is described as Navngivelse 4.0 Internasjonal