Blar i forfatter "Jensen, Hallvard"

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    • En mulighetsstudie for økt vekst innen innlandsoppdrett 

      Winther, Ulf; Prestvik, Øyvind; Ulgenes, Yngve; Heide, Mats Augdal; Nilssen, Frode; Haug, Lise; Uhlig, Christian; Jensen, Hallvard; Siikavuopio, Sten Ivar; Sæther, Bjørn-Steinar (Research report; Forskningsrapport, 2010-06-29)
      SINTEF Fiskeri og havbruk har sammen med Bioforsk Nord og Nofuna Marked gjennomført en vurdering av mulighetene for økt vekst innen innlandsoppdrett i Norge. Følgende arter er vurdert: Røye, ørret, sik, regnbueørret, gjørs, abbor og lake. Studien gir en oversikt over innlandsoppdrett i Norge og i andre nordiske land. Mulighetene for utvikling av en innlandsoppdrettsnæring i Norge er ellers vurdert ...

    • Feeding ecology of piscivorous brown trout (Salmo trutta L.) in a subarctic watercourse 

      Jensen, Hallvard; Bøhn, Thomas; Amundsen, Per-Arne; Aspholm, Paul Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2004-02)
      Feeding ecology of piscivorous brown trout was studied in the Pasvik watercourse, Norway and Russia. The watercourse is heavily regulated for hydroelectric purposes, and 5000 brown trout > 25 cm are stocked annually to compensate the negative impacts of the impoundments. Stocked and wild trout had almost identical diets consisting mainly of vendace Coregonus albula and partly of whitefish Coregonus ...

    • Predation by brown trout (Salmo trutta) along a diversifying prey community gradient 

      Jensen, Hallvard; Kahilainen, Kimmo K.; Amundsen, Per-Arne; Gjelland, Karl øystein; Tuomaala, Anti; Malinen, Tommy; Bøhn, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2008-08-07)
      Predation has a fundamental role in aquatic ecosystems, but the relative importance of factors governing prey selection by predators remains controversial. In this study, we contrast five lakes of a subarctic watershed to explore how prey community characteristics affect prey selection and growth rate of the common top predator, brown trout (<i>Salmo trutta</i>). The lakes constitute a distinct ...

    • Prey consumption rates and growth of piscivorous brown trout in a subarctic watercourse 

      Jensen, Hallvard; Amundsen, Per-Arne; Elliott, J. Malcolm; Bøhn, Thomas; Aspholm, Paul Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2006-02-28)
      Prey consumption rates of piscivorous brown trout <i>Salmo trutta</i> were studied in the Pasvik watercourse, which forms the border between Norway and Russia. Estimates of food consumption in the field were similar to or slightly less than maximum values from a bioenergetic model. The piscivore diet consisted mainly of vendace <i>Coregonus albula</i> with a smaller number of whitefish <i>Coregonus ...

    • Resource Partitioning in Food, Space and Time between Arctic Charr (Salvelinus alpinus), Brown Trout (Salmo trutta) and European Whitefish (Coregonus lavaretus) at the Southern Edge of Their Continuous Coexistence 

      Jensen, Hallvard; Kiljunen, Mikko; Knudsen, Rune; Amundsen, Per-Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      Arctic charr and European whitefish are considered to be strong competitors in lakes, with the latter usually being the superior species. However, high niche plasticity and lake morphometry may suggestively facilitate resource partitioning and coexistence between charr and whitefish. Here, we explore the trophic niche utilization (diet and habitat use) of charr and whitefish co-occurring with brown ...

    • Salmon-lice as a potential threat to anadromous Arctic charr populations 

      Rochat, Eloïse Coralie; Grenier, Gabrielle; Muladal, Rune; Jensen, Hallvard; Knudsen, Rune (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-25)
      Salmon-lice have the potential to change the behaviour and growth of their salmonid host species. Here, the baseline infection levels of salmon-lice of post-smolts (n = 815) and veteran migrants (n = 875) of sea-run Arctic charr (Salvelinus alpinus Linnaeus, 1758) were monitored over two successive years in a sub-Arctic Norwegian fjord without farming of salmonids. All Arctic charr were collected ...