Blar i Brage IMR på forfatter "Skjæraasen, Jon Egil"

Viser treff 1-20 av 29

    • Attraction of cod Gadus morhua from coastal spawning grounds to salmon farms 

      Skjæraasen, Jon Egil; Karlsen, Ørjan; Langangen, Øystein Ole Gahr; Meier, Sonnich; Dunlop, Katherine Mary; van der Meeren, Terje; Keeley, Nigel B.; Myksvoll, Mari Skuggedal; Dahle, Geir; Moland, Even; Nilsen, Rune; Elvik, Kristine Marit Schrøder; Bannister, Raymond; Olsen, Esben Moland (Peer reviewed; Journal article, 2022)
      Wild fish aggregate at aquaculture net-pens, but the underlying mechanisms are not fully understood. This study examined how salmon farms attract coastal Atlantic cod Gadus morhua from their inshore spawning grounds. ...

    • Attraction of cod Gadus morhua from coastal spawning grounds to salmon farms 

      Skjæraasen, Jon Egil; Karlsen, Ørjan; Langangen, Øystein Ole Gahr; Meier, Sonnich; Dunlop, Katherine Mary; van der Meeren, Terje; Keeley, Nigel B.; Myksvoll, Mari Skuggedal; Dahle, Geir; Moland, Even; Nilsen, Rune; Elvik, Kristine Marit Schrøder; Bannister, Raymond; Olsen, Esben Moland (Peer reviewed; Journal article, 2022)
      Wild fish aggregate at aquaculture net-pens, but the underlying mechanisms are not fully understood. This study examined how salmon farms attract coastal Atlantic cod Gadus morhua from their inshore spawning grounds. ...

    • Behavioural responses of wild, spawning Atlantic cod (Gadus morhua L.) to seismic airgun exposure 

      McQueen, Kate; Skjæraasen, Jon Egil; Nyqvist, D; Olsen, Esben Moland; Karlsen, Ørjan; Meager, Justin James; Kvadsheim, Petter Helgevold; Handegard, Nils Olav; Forland, Tonje Nesse; de Jong, Karen; Sivle, Lise Doksæter (Peer reviewed; Journal article, 2023)
      Seismic airgun surveys to map petroleum deposits in the seabed may impact behaviour of marine animals over large distances. Understanding whether fish spawning behaviour is affected by this anthropogenic noise source is ...

    • Environmental regulation of individual depth on a cod spawning ground 

      Meager, Justin J.; Skjæraasen, Jon Egil; Karlsen, Ørjan; Løkkeborg, Svein; Mayer, Ian; Michalsen, Kathrine; Nilsen, Trygve; Fernö, Anders (Journal article; Peer reviewed, 2012-12-13)
      Fine-scale characteristics of spawning grounds may provide the opportunity for cod Gadus morhua L. to regulate their external environment by adjusting their depth. Ultrasonic telemetry was used to study how the environment ...

    • From “where” and “when” to “what” and “why”: archival tags for monitoring “complex” behaviours in fish. 

      Metcalfe, Julian D.; Wilson, R.P.; Kjesbu, Olav Sigurd; Challiss, M.J.; Gleiss, A.; Skjæraasen, Jon Egil; Clarke, S. (ICES CM documents;2009/B:04, Working paper, 2009)
      Understanding the movements (“where” and “when”) and behaviour (“what” and, hopefully, “why”) of individuals and populations is key to answering fundamental questions in fish ecology. The use of archival tags in telemetry ...

    • Habitat associations of juvenile Atlantic cod (Gadus morhua L.) and sympatric demersal fish communities within shallow inshore nursery grounds 

      Dunlop, Katherine Mary; Staby, Arved; van der Meeren, Terje; Keeley, Nigel B.; Olsen, Esben Moland; Bannister, Raymond; Skjæraasen, Jon Egil (Peer reviewed; Journal article, 2022)
      Resolving the relationship between demersal fish and sublittoral biotic habitats and substrates is a key element in the protection of important nursery grounds for strengthening fish recruitment. In Norway, coastal Atlantic ...

    • Highly mixed impacts of near-future climate change on stock productivity proxies in the North East Atlantic 

      Kjesbu, Olav Sigurd; Sundby, Svein; Sandø, Anne Britt; Alix, Maud; Hjøllo, Solfrid Sætre; Tiedemann, Maik; Skern-Mauritzen, Mette; Junge, Claudia; Fossheim, Maria; Broms, Cecilie; Søvik, Guldborg; Zimmermann, Fabian; Nedreaas, Kjell Harald; Eriksen, Elena; Höffle, Hannes; Hjelset, Ann Merete; Kvamme, Cecilie; Reecht, Yves; Knutsen, Halvor; Aglen, Asgeir; Albert, Ole Thomas; Berg, Erik; Bogstad, Bjarte; Durif, Caroline; Halvorsen, Kim Aleksander Tallaksen; Høines, Åge Sigurd; Hvingel, Carsten; Johannesen, Edda; Johnsen, Espen; Moland, Even; Myksvoll, Mari Skuggedal; Nøttestad, Leif; Olsen, Erik Joel Steinar; Skaret, Georg; Skjæraasen, Jon Egil; Slotte, Aril; Staby, Arved; Stenevik, Erling Kåre; Stiansen, Jan Erik; Stiasny, Martina H.; Sundet, Jan Henry; Vikebø, Frode Bendiksen; Huse, Geir (Peer reviewed; Journal article, 2021)
      Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources—ranging from data-poor to data-rich stocks—in the ...

    • Large annual variation in the amount of skipped spawning for female Northeast Arctic haddock Melanogrammus aeglefinus 

      Skjæraasen, Jon Egil; Korsbrekke, Knut; Dingsør, Gjert Endre; Langangen, Øystein; Opdal, Anders Frugård; Jørgensen, Christian (Peer reviewed; Journal article, 2020)
      Although the phenomenon of skipped spawning has been described in numerous fishes, time-series are scarce. We used the presence of post-ovulatory follicles in histological gonad slides from females not developing oocytes ...

    • Large annual variation in the amount of skipped spawning for female Northeast Arctic haddock Melanogrammus aeglefinus 

      Skjæraasen, Jon Egil; Korsbrekke, Knut; Dingsør, Gjert Endre; Langangen, Øystein; Opdal, Anders Frugård; Jørgensen, Christian (Peer reviewed; Journal article, 2020)
      Although the phenomenon of skipped spawning has been described in numerous fishes, time-series are scarce. We used the presence of post-ovulatory follicles in histological gonad slides from females not developing oocytes ...

    • Liver energy, atresia and oocyte stage influence fecundity regulation in Northeast Arctic cod 

      Skjæraasen, Jon Egil; Nash, Richard D.M.; Kennedy, James; Thorsen, Anders; Nilsen, Trygve; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2010-04-08)
      Marine ecosystems are changing; global warming-induced increases in water temperatures and fishing have caused truncated age structures and small sizes at maturity in many stocks. This may affect both populations’ total ...

    • Making use of Johan Hjort's “unknown” legacy: reconstruction of a 150-year coastal time-series on northeast Arctic cod (Gadus morhua) liver data reveals long-term trends in energy 

      Kjesbu, Olav Sigurd; Opdal, Anders Frugård; Korsbrekke, Knut; Devine, Jennifer A.; Skjæraasen, Jon Egil (Journal article; Peer reviewed, 2014-03-11)
      Hidden within the seminal 1914 publication by Johan Hjort, we find what is probably one of the first comprehensive teleost time-series ever published. The series is liver size and fat content of northeast Arctic (NEA) cod ...

    • 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 ...

    • Mechanisms regulating oocyte recruitment and skippedspawning in Northeast Arctic cod (Gadus morhua L.) 

      Skjæraasen, Jon Egil; Kennedy, James; Thorsen, Anders; Fonn, Merete; Strand, Bente; Mayer, Ian; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2009-09)
      To examine mechanisms that affect fecundity, atresia and skipped spawning in Northeast Arctic cod (Gadus morhua L.), we conducted an experiment where wild-caught cod (>60 cm) kept under restricted food regimes were subjected ...

    • Mechanisms regulating oocyte recruitment and skippedspawning in Northeast Arctic cod (Gadus morhua L.) 

      Skjæraasen, Jon Egil; Kennedy, James; Thorsen, Anders; Fonn, Merete; Strand, Bente; Mayer, Ian; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2009-09)
      To examine mechanisms that affect fecundity, atresia and skipped spawning in Northeast Arctic cod (Gadus morhua L.), we conducted an experiment where wild-caught cod (>60 cm) kept under restricted food regimes were subjected ...

    • 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 ...

    • Skipped spawning in Northeast Arctic haddock Melanogrammus aeglefinus 

      Skjæraasen, Jon Egil; Korsbrekke, Knut; Nilsen, Trygve; Fonn, Merete; Kjesbu, Olav Sigurd; Dingsør, Gjert Endre; Nash, Richard David Marriott (Journal article; Peer reviewed, 2015-04-22)

    • Sluttrapport fra ICOD-prosjektet - Arbeidspakke 2: Egg- og yngelundersøkelser på gyte- og oppvekstområder på Smøla og i Aure i forbindelse med etablering av oppdrettsanlegg nær lokale gyteområder for kysttorsk 

      van der Meeren, Terje; Meier, Sonnich; Myksvoll, Mari Skuggedal; Dahle, Geir; Karlsen, Ørjan; Staby, Arved; Mjanger, Hildegunn; Engevik, Annhild; Dunlop, Katherine Mary; Bannister, Raymond; Skjæraasen, Jon Egil (Rapport fra havforskningen;2021 - 32, Research report, 2021)
      ICOD-prosjektet ble etablert for å undersøke mulige interaksjoner mellom oppdrettsanlegg og nærliggende gyteområder for kysttorsk. Rapporten presenterer resultater fra ICOD som omfatter egg- og yngelundersøkelser foretatt ...

    • 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 ...