Blar i Articles på forfatter "Karlsen, Ørjan"

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    • Growth of wild and domesticated Atlantic cod Gadus morhua reared under semi-commercial conditions 

      Otterå, Håkon Magne; Heino, Mikko; Sørvik, Anne Grete Eide; Svåsand, Terje; Karlsen, Ørjan; Thorsen, Anders; Glover, Kevin (Journal article; Peer reviewed, 2018)
      Genetic interactions between farmed escapees and wild fish represent a challenge to environmentally sustainable aquaculture. Breeding programs for Atlantic cod Gadus morhua have been initiated; however, the genetic response ...

    • Impacts of salmon lice on mortality, marine migration distance and premature return in sea trout 

      Serra Llinares, Rosa Maria; Bøhn, Thomas; Karlsen, Ørjan; Nilsen, Rune; Freitas, Carla; Albretsen, Jon; Haraldstad, Tormod; Thorstad, Eva Bonsak; Elvik, Kristine Marit Schrøder; Bjørn, Pål Arne (Peer reviewed; Journal article, 2020)
      Brown trout Salmo trutta (L.) is a facultative anadromous species, where a portion of individuals in populations with access to the sea perform migrations to use the richer feeding resources. We investigated the effect of ...

    • Impacts of wild fishes attracted to open-cage salmonid farms in Norway 

      Uglem, Ingebrigt; Karlsen, Ørjan; Sánchez-Jerez, Pablo; Sæther, Bjørn-Steinar (Journal article; Peer reviewed, 2014-12-02)
      Salmonid farming affects both the environment and other industries, with impacts of wild fish attracted to fish farms being a major concern. Here, we summarized existing knowledge on the impacts of such aggregations around ...

    • In sea trout, the physiological response to salmon louse is stronger in female than in males 

      Fjelldal, Per Gunnar; Dalvin, Sussie Trine; Ugelvik, Mathias Stølen; Pedersen, Audun Østby; Hansen, Tom Johnny; Skjold, Bjørnar; Dyrhovden, Lise; Kroken, Ann-Kathrin Jakobsen; Karlsen, Ørjan (Peer reviewed; Journal article, 2023)
      The aims of this study were to compare male and female sea trout (Salmo trutta) with respect to their hypo-osmoregulatory ability over a simulated migration to seawater and their clinical and physiological response to ...

    • Inferring Atlantic salmon post-smolt migration patterns using genetic assignment 

      Harvey, Alison C.; Sanchez, Maria Quintela; Glover, Kevin; Karlsen, Ørjan; Nilsen, Rune; Skaala, Øystein; Sægrov, Harald; Kolås, Steinar; Knutar, Sofie; Wennevik, Vidar (Journal article; Peer reviewed, 2019)
      Understanding migratory patterns is important for predicting and mitigating unwanted consequences of environmental change or anthropogenic challenges on vulnerable species. Wild Atlantic salmon undergo challenging migrations ...

    • Limited evidence for differential reproductive fitness of wild Atlantic cod in two areas of high and low salmon farming density 

      Barrett, Luke; Swearer, Stephen E.; Harboe, Torstein; Karlsen, Ørjan; Meier, Sonnich; Dempster, Timothy David (Journal article; Peer reviewed, 2018)
      Sea cage fish aquaculture attracts large aggregations of wild fish that feed on farm waste. Fish that associate closely with farms undergo physiological changes, and captive feeding trials indicate possible negative effects ...

    • Mating competition between farmed and wild cod Gadus morhua 

      Skjæraasen, Jon Egil; Meager, Justin J.; Karlsen, Ørjan; Mayer, Ian; Dahle, Geir; Rudolfsen, Geir; Fernö, Anders (Journal article; Peer reviewed, 2010-08-18)
      Increasing numbers of hatchery-produced fish entering marine environments has caused concern over potential fitness depressions in wild populations, yet no study has addressed the likelihood of hybridisation between farmed ...

    • Migration of Atlantic salmon post-smolts in a fjord with high infestation pressure of salmon lice 

      Halttunen, Elina; Gjelland, Karl Øystein; Glover, Kevin; Johnsen, Ingrid Askeland; Serra-Llinares, Rosa-Maria; Skaala, Øystein; Nilsen, Rune; Bjørn, Pål Arne; Karlsen, Ørjan; Finstad, Bengt; Skilbrei, Ove Tommy (Peer reviewed; Journal article, 2018)
      Understanding Atlantic salmon Salmo salar post-smolt coastal migration behaviour is crucial for predicting their exposure to ecological challenges such as the parasite salmon louse Lepeophtheirus salmonis. We compared the ...

    • Movement diversity and partial sympatry of coastal and Northeast Arctic cod ecotypes at high latitudes 

      Strøm, John Fredrik; Bøhn, Thomas; Skjæraasen, Jon Egil; Gjelland, Karl Øystein; Karlsen, Ørjan; Johansen, Torild; Hanebrekke, Tanja Lexau; Bjørn, Pål Arne; Olsen, Esben Moland (Peer reviewed; Journal article, 2023)
      Movement diversity within species represent an important but often neglected, component of biodiversity that affects ecological and genetic interactions, as well as the productivity of exploited systems. By combining ...

    • Movement diversity and partial sympatry of coastal and Northeast Arctic cod ecotypes at high latitudes 

      Strøm, John Fredrik; Bøhn, Thomas; Skjæraasen, Jon Egil; Gjelland, Karl Øystein; Karlsen, Ørjan; Johansen, Torild; Hanebrekke, Tanja Lexau; Bjørn, Pål Arne; Olsen, Esben Moland (Peer reviewed; Journal article, 2023)
      Movement diversity within species represent an important but often neglected, component of biodiversity that affects ecological and genetic interactions, as well as the productivity of exploited systems. By combining ...

    • Occurrence of salmonid alphavirus and piscine orthoreovirus-1 infections in migrating salmon (Salmo salar L.) post-smolt in western Norway 

      Madhun, Abdullah Sami; Nilsen, Rune; Barlaup, Bjørn Torgeir; Karlsen, Ørjan; Karlsbakk, Egil Erlingsson (Peer reviewed; Journal article, 2023)
      Viral diseases are a serious problem in Atlantic salmon (Salmo salar L.) farming in Norway, often leading to reduced fish welfare and increased mortality. Disease outbreaks in salmon farms may lead to spread of viruses to ...

    • Offshore crude oil disrupts retinoid signaling and eye development in larval Atlantic haddock 

      Lie, Kai Kristoffer; Meier, Sonnich; Sørhus, Elin; Edvardsen, Rolf; Karlsen, Ørjan; Olsvik, Pål Asgeir (Journal article; Peer reviewed, 2019)
      The aim of this study was to examine the impact of dispersed crude oil on retinoid metabolism and signaling in developing haddock larvae (Melanogrammus aeglefinus). Retinoids and its active metabolites are involved in the ...

    • Oil droplet fouling and differential toxicokinetics of polycyclic aromatic hydrocarbons in embryos of Atlantic haddock and cod 

      Sørensen, Lisbet; Sørhus, Elin; Nordtug, Trond; Incardona, John P.; Linbo, Tiffany; Giovanetti, Laura; Karlsen, Ørjan; Meier, Sonnich (Peer reviewed; Journal article, 2017)
      The impact of crude oil pollution on early life stages (ELS) of fish, including larvae and embryos, has received considerable attention in recent years. Of the organic components present in crude oil, polycyclic aromatic ...

    • Ontogeny-Specific Skeletal Deformities in Atlantic Haddock Caused by Larval Oil Exposure 

      Olsvik, Pål Asgeir; Sørhus, Elin; Meier, Sonnich; Torvanger, Ingrid; Thorbjørnsen, Maja; Thorsen, Anders; Sørensen, Lisbet; Fjelldal, Per Gunnar; Karlsen, Ørjan; Guimaraes, Igo G.; Lie, Kai Kristoffer (Peer reviewed; Journal article, 2021)
      Bone deformities are one of the main effects of crude oil exposure in marine fish larvae. Craniofacial and jaw deformities, if severe enough, may restrict feeding and ultimately kill the developing larvae. This study aimed ...

    • Ossification of Atlantic cod (Gadus morhua) – Developmental stages revisited 

      Sæle, Øystein; Haugen, Trine; Karlsen, Ørjan; van der Meeren, Terje; Bæverfjord, Grete; Hamre, Kristin; Rønnestad, Ivar; Moren, Mari; Lie, Kai Kristoffer (Peer reviewed; Journal article, 2017)
      In studies of marine larvae, it is common to use days post-hatch as a developmental reference point. We show that age is a poor measure of morphological and physiological development in Atlantic cod. Therefore, we propose ...

    • Risk assessment of the environmental impact of Norwegian Atlantic salmon farming 

      Taranger, Geir Lasse; Karlsen, Ørjan; Bannister, Raymond; Glover, Kevin; Husa, Vivian; Karlsbakk, Egil; Kvamme, Bjørn Olav; Boxaspen, Karin Kroon; Bjørn, Pål Arne; Finstad, Bengt; Madhun, Abdullah Sami; Morton, Hugh Craig; Svåsand, Terje (Journal article; Peer reviewed, 2014-09-02)
      Norwegian aquaculture has grown from its pioneering days in the 1970s to be a major industry. It is primarily based on culturing Atlantic salmon and rainbow trout and has the potential to influence the surrounding environment ...

    • Salmon lice threaten growth, osmoregulation and survival in anadromous Arctic char post-smolts 

      Fjelldal, Per Gunnar; Hansen, Tom Johnny; Karlsen, Ørjan; Wright, Daniel William (Peer reviewed; Journal article, 2019)
      High salmon lice (Lepeophtheirus salmonis) infestation levels resulting from intensive salmonid sea-cage aquaculture can threaten populations of wild salmonid hosts. This includes anadromous Arctic char (Salvelinus alpinus), ...

    • Salmon lice-induced mortality of Atlantic salmon during post-smolt migration in Norway 

      Johnsen, Ingrid Askeland; Harvey, Alison C.; Sævik, Pål Næverlid; Sandvik, Anne Dagrun; Ugedal, Ola; Ådlandsvik, Bjørn; Wennevik, Vidar; Glover, Kevin; Karlsen, Ørjan (Peer reviewed; Journal article, 2020)

    • Salmon louse infestation levels on sea trout can be predicted from a hydrodynamic lice dispersal model 

      Bøhn, Thomas; Nilsen, Rune; Gjelland, Karl Øystein; Biuw, Martin; Sandvik, Anne Dagrun; Primicerio, Raul; Karlsen, Ørjan; Serra Llinares, Rosa Maria (Peer reviewed; Journal article, 2021)
      The abundance of the parasitic salmon louse has increased with the growth in aquaculture of salmonids in open net pens. This represents a threat to wild salmonid populations as well as a key limiting factor for salmon ...

    • Sea trout adapt their migratory behaviour in response to high salmon lice concentrations 

      Halttunen, Elina; Gjelland, Karl Øystein; Hamel, Sandra; Serra-Llinares, Rosa Maria; Nilsen, Rune; Arechavala-Lopez, Pablo; Skardhamar, Jofrid; Johnsen, Ingrid Askeland; Asplin, Lars; Karlsen, Ørjan; Bjørn, Pål Arne; Finstad, Bengt (Peer reviewed; Journal article, 2017)
      Sea trout face growth – mortality trade-offs when entering the sea to feed. Salmon lice epizootics resulting from aquaculture have shifted these trade-offs, as salmon lice might both increase mortality and reduce growth ...