Blar i Articles på forfatter "Karlsen, Ørjan"
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Spawning Atlantic cod (Gadus morhua L.) exposed to noise from seismic airguns do not abandon their spawning site
McQueen, Kate; Meager, Justin James; Nyqvist, Daniel; Skjæraasen, Jon Egil; Olsen, Esben Moland; Karlsen, Ørjan; Kvadsheim, Petter Helgevold; Handegard, Nils Olav; Sivle, Lise Doksæter; Forland, Tonje Nesse (Peer reviewed; Journal article, 2022)Seismic airgun surveys may disturb and displace fish at large ranges. If such displacement causes fish to abandon spawning grounds, reproductive success could be impacted. To investigate whether airgun sound causes cod ... -
Sperm characteristics and competitive ability in farmed and wild cod
Skjæraasen, Jon Egil; Mayer, Ian; Meager, Justin J.; Rudolfsen, Geir; Karlsen, Ørjan; Haugland, Thomas; Kleven, Oddmund (Journal article; Peer reviewed, 2009-01-27)The development of cod aquaculture has raised concerns about its effect on wild stocks. One risk is hybridisation between escapees and wild cod, causing genetic introgression, and, potentially, fitness depressions in wild ... -
Terrestrial fatty acids from feed oil in feed for farmed salmonids are transferred to the liver, gonads, and muscle of wild Atlantic cod (Gadus morhua)
Meier, Sonnich; van der Meeren, Terje; Skjæraasen, Jon Egil; Bannister, Raymond; Rasinger, Josef; Karlsen, Ørjan (Peer reviewed; Journal article, 2023)Wild fish attracted to salmon farms feed on waste feed that presently contain high levels of fatty acids of terrestrial origin. This study examines whether mature Atlantic cod (Gadus morhua) caught at spawning grounds has ... -
The ontogeny and brain distribution dynamics of the appetite regulators NPY, CART and pOX in larval Atlantic cod (Gadus morhua L.)
Le, Hoang T.M.D.; Angotzi, Anna Rita; Ebbesson, Lars O.E.; Karlsen, Ørjan; Rønnestad, Ivar (Journal article; Peer reviewed, 2016-04-21)Similar to many marine teleost species, Atlantic cod undergo remarkable physiological changes during the early life stages with concurrent and profound changes in feeding biology and ecology. In contrast to the digestive ... -
The two-step development of a duplex retina involves distinct events of cone and rod neurogenesis and differentiation
Valen, Ragnhild; Eilertsen, Mariann; Edvardsen, Rolf; Furmanek, Tomasz; Rønnestad, Ivar; van der Meeren, Terje; Karlsen, Ørjan; Nilsen, Tom Ole; Helvik, Jon Vidar (Peer reviewed; Journal article, 2016) -
Timecourse of oocyte development in saithe Pollachius virens
Skjæraasen, Jon Egil; Devine, Jennifer Ann; Godiksen, Jane Aanestad; Fonn, Merete; Otterå, Håkon Magne; Kjesbu, Olav Sigurd; Norberg, Birgitta; Langangen, Øystein; Karlsen, Ørjan (Journal article; Peer reviewed, 2017)Wild caught North Sea saithe Pollachius virens were monitored for growth, sex steroid profiles and oocyte development pre-spawning and measured for egg size and group fecundity during the spawning season in the laboratory. ... -
Timing is everything: Survival of Atlantic salmon Salmo salar postsmolts during events of high salmon lice densities
Bøhn, Thomas; Gjelland, Karl Øystein; Serra Llinares, Rosa Maria; Finstad, Bengt; Primicerio, Raul; Nilsen, Rune; Karlsen, Ørjan; Sandvik, Anne Dagrun; Skilbrei, Ove Tommy; Elvik, Kristine Marit Schrøder; Skaala, Øystein; Bjørn, Pål Arne (Peer reviewed; Journal article, 2020)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. In this study, n = 29,817 tagged Atlantic salmon were studied ... -
Towards cod without spawning: artificial continuous light in submerged sea-cages maintains growth and delays sexual maturation for farmed Atlantic cod Gadus morhua
Korsøen, Øyvind Johan; Dempster, Tim; Fosseidengen, Jan Erik; Karlsen, Ørjan; Oppedal, Frode; Stien, Lars Helge; Kristiansen, Tore S. (Journal article; Peer reviewed, 2013-06-04)Sexual maturation and spawning in sea-cages is a major production and environmental challenge for the Atlantic cod farming industry. Altered photoperiod has arrested sexual maturation in cod kept in indoor or covered ... -
Towards direct evidence of the effects of salmon lice (Lepeophtheirus salmonis Kr?yer) on sea trout (Salmo trutta L.) in their natural habitat: proof of concept for a new combination of methods
Serra Llinares, Rosa Maria; Freitas, Carla; Nilsen, Rune; Elvik, Kristine Marit Schrøder; Albretsen, Jon; Bøhn, Thomas; Karlsen, Ørjan; Bjørn, Pål Arne (Journal article; Peer reviewed, 2018)Studies addressing the impact of salmon lice (Lepeophtheirus salmonis Krøyer) on sea trout in their natural habitat are scarce and mostly limited to prophylaxis-based experiments. The main drawbacks with this approach are ... -
Unexpected Interaction with Dispersed Crude Oil Droplets Drives Severe Toxicity in Atlantic Haddock Embryos
Sørhus, Elin; Edvardsen, Rolf B.; Karlsen, Ørjan; Nordtug, Trond; van der Meeren, Terje; Thorsen, Anders; Harman, Christopher; Jentoft, Sissel; Meier, Sonnich (Journal article; Peer reviewed, 2015-04-29)The toxicity resulting from exposure to oil droplets in marine fish embryos and larvae is still subject for debate. The most detailed studies have investigated the effects of water-dissolved components of crude oil in water ... -
Untangling mechanisms of crude oil toxicity: Linking gene expression, morphology and PAHs at two developmental stages in a cold-water fish
Sørhus, Elin; Donald, Carey; Da Silva, Denis; Thorsen, Anders; Karlsen, Ørjan; Meier, Sonnich (Peer reviewed; Journal article, 2020) -
Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua
Meager, Justin J.; Skjæraasen, Jon Egil; Fernö, Anders; Karlsen, Ørjan; Løkkeborg, Svein; Michalsen, Kathrine; Utskot, Stig Ove (Journal article; Peer reviewed, 2009-09-04)Rapid development of fish mariculture and efforts to restock depleted populations have raised concerns about the effects on wild populations and the risk of genetic introgression from hybridisation. Reproduction of many ... -
Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua
Meager, Justin J.; Skjæraasen, Jon Egil; Fernö, Anders; Karlsen, Ørjan; Løkkeborg, Svein; Michalsen, Kathrine; Utskot, Stig Ove (Journal article; Peer reviewed, 2009-09-04)Rapid development of fish mariculture and efforts to restock depleted populations have raised concerns about the effects on wild populations and the risk of genetic introgression from hybridisation. Reproduction of many ... -
Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua
Meager, Justin J.; Skjæraasen, Jon Egil; Fernö, Anders; Karlsen, Ørjan; Løkkeborg, Svein; Michalsen, Kathrine; Utskot, Stig Ove (Journal article; Peer reviewed, 2009-09-04)Rapid development of fish mariculture and efforts to restock depleted populations have raised concerns about the effects on wild populations and the risk of genetic introgression from hybridisation. Reproduction of many ...