title: Does density influence relative growth performance of farm, wild and F1 hybrid Atlantic salmon in semi-natural and hatchery common garden conditions?
abstract: The conditions encountered by Atlantic salmon, Salmo salar L., in aquaculture are markedly different from the natural environment. Typically, farmed salmon experience much higher densities than wild individuals, and may therefore have adapted to living in high densities. Previous studies have demonstrated that farmed salmon typically outgrow wild salmon by large ratios in the hatchery, but these differences are much less pronounced in the wild. Such divergence in growth may be explained partly by the offspring of wild salmon experiencing higher stress and thus lower growth when compared under high-density farming conditions. Here, growth of farmed, wild and F1 hybrid salmon was studied at contrasting densities within a hatchery and semi-natural environment. Farmed salmon significantly outgrew hybrid and wild salmon in all treatments. Importantly, however, the reaction norms were similar across treatments for all groups. Thus, this study was unable to find evidence that the offspring of farmed salmon have adapted more readily to higher fish densities than wild salmon as a result of domestication. It is suggested that the substantially higher growth rate of farmed salmon observed in the hatchery compared with wild individuals may not solely be caused by differences in their ability to grow in high-density hatchery scenarios.
authors: Molecular Ecology and Fisheries Genetics Laboratory , Bangor University , Bangor, Gwynedd LL57 2DG , UK.
authors: Alison C
authors: 0000-0001-8422-8763
authors: AC
authors: Harvey
authors: Molecular Ecology and Fisheries Genetics Laboratory , Bangor University , Bangor, Gwynedd LL57 2DG , UK.
authors: Gareth
authors: G
authors: Juleff
authors: Molecular Ecology and Fisheries Genetics Laboratory , Bangor University , Bangor, Gwynedd LL57 2DG , UK.
authors: Gary R
authors: GR
authors: Carvalho
authors: Molecular Ecology and Fisheries Genetics Laboratory, Bangor University, Bangor, Gwynedd LL57 2DG, UK; Biological Sciences, University of East Anglia, Norwich, UK.
authors: Martin I
authors: MI
authors: Taylor
authors: Havforskningsinstituttet , Bergen , Norway.
authors: Monica F
authors: 0000-0002-5844-9498
authors: MF
authors: Solberg
authors: Molecular Ecology and Fisheries Genetics Laboratory , Bangor University , Bangor, Gwynedd LL57 2DG , UK.
authors: Simon
authors: S
authors: Creer
authors: Havforskningsinstituttet , Bergen , Norway.
authors: Lise
authors: L
authors: Dyrhovden
authors: Havforskningsinstituttet , Bergen , Norway.
authors: Ivar-Helge
authors: IH
authors: Matre
authors: Havforskningsinstituttet, Bergen, Norway; Sea Lice Research Centre, Universitetet i Bergen Institutt for Biologi, Bergen, Norway.
authors: Kevin A
authors: KA
authors: Glover
keywords: density; domestication; farm escapes; genetic interaction; growth; hybridization