Blar i NTNU Open på forfatter "Ugedal, Ola"

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    • Biologiske undersøkelser i Altaelva 1981-2006. Oppsummering av kraftreguleringens konsekvenser for laksebestanden 

      Ugedal, Ola; Thorstad, Eva B.; Finstad, Anders G.; Fiske, Peder; Forseth, Torbjørn; Hvidsten, Nils Arne; Jensen, Arne J.; Koksvik, Jan Ivar; Reinertsen, Helge; Saksgård, Laila; Næsje, Tor F. (NINA rapport;, Research report, 2007)
      Nøkkelord : kraftregulering, Altaelva, Finnmark, laks, laksefangster, ungfisktetthet, vinterdødelighet, smoltproduksjon, bunnfauna, begroing

    • Biologiske undersøkelser i Altaelva 2004 

      Ugedal, Ola; Thorstad, Eva B.; Næsje, Tor F.; Reinertsen, Helge; Koksvik, Jan Ivar; Saksgård, Laila; Hvidsten, Nils Arne; Blom, Hans H.; Fiske, Peder; Jensen, Arne J. (NINA-rapport;43, Research report, 2005)
      Altaelva er ei av Norges beste elver for sportsfiske etter laks. Elva har en storvokst laksestamme, og en unik kultur og historie knyttet til laksefisket. Stortinget vedtok å utbygge og regulere elva for kraftproduksjon i ...

    • Can variation in standard metabolic rate explain context- dependent performance of farmed Atlantic salmon offspring? 

      Robertsen, Grethe; Reid, Donald; Einum, Sigurd; Aronsen, Tonje; Fleming, Ian A.; Sundt-Hansen, Line Elisabeth Breivik; Karlsson, Sten; Kvingedal, Eli; Ugedal, Ola; Hindar, Kjetil (Journal article; Peer reviewed, 2018)
      Escaped farmed Atlantic salmon interbreed with wild Atlantic salmon, leaving off- spring that often have lower success in nature than pure wild salmon. On top of this, presence of farmed salmon descendants can impair ...

    • Classification of hydropeaking impacts on Atlantic salmon populations in regulated rivers 

      Bakken, Tor Haakon; Harby, Atle; Forseth, Torbjørn; Ugedal, Ola; Sauterleute, Julian Friedrich; Halleraker, Jo Halvard; Alfredsen, Knut (Peer reviewed; Journal article, 2021)
      This article proposes and demonstrates a new classification system of fish population level effects of hydropeaking operations in rivers. The classification of impacts is developed along two axes; first, the hydromorphological ...

    • Density independent use of shallow riverine areas in juvenile Atlantic salmon 

      Puffer, Michael; Berg, Ole Kristian; Hamnes, Frøydis Bolme; Bentsen, Vidar; Koch, Wouter; Ugedal, Ola; Forseth, Torbjørn; Arnekleiv, Jo Vegar; Einum, Sigurd (Journal article; Peer reviewed, 2018)
      Habitat use of aquatic organisms is essential to evaluate effects of many environmental challenges like effects of hydro-power regulation, where stranding may occur under hydropeaking (rapid dewatering of shallow river ...

    • Development of a risk assessment for sea trout in coastal areas exploited for aquaculture 

      Finstad, Bengt; Sandvik, Anne Dagrun; Ugedal, Ola; Vollset, Knut; Karlsen, Ørjan; Davidsen, Jan Grimsrud; Sægrov, Harald; Lennox, Robert J. (Peer reviewed; Journal article, 2021)
      ABSTRACT: The regulation of aquaculture production in Norway considers the potential impact of salmon lice on wild fish. However, most attention has been focused on impacts on wild Atlantic salmon, despite the fact that ...

    • Effektivitet og kost-nytte forhold av fysiske miljøtiltak i vassdrag 

      Pulg, Ulrich; Stranzl, Sebastian Franz; Espedal, Espen Olsen; Gabrielsen, Sven Erik; Postler, Christoph; Ugedal, Ola; Jensås, Jan Gunnar; Bremset, Gunnbjørn; Fjeldstad, Hans-Petter; Alfredsen, Knut (LFI - Laboratorium for ferskvannsøkologi og innlandsfiske;, Research report, 2020)
      Det er økt fokus på bedring av fysiske miljøforhold i vassdrag, og med dette har behovet for å kunne vurdere kostnader og nytte ved slike tiltak økt. Prinsippet om «positiv kost-nytte» legges eksempelvis til grunn ved ...

    • Estimering av effektivt antall gytefisk fra stikkprøver av ungfisk av laks - Betydning av antall genetiske markører, antall prøver og romlig fordeling 

      Wacker, Sebastian; Aronsen, Tonje; Hagen, Ingerid Julie; Karlsson, Sten; Berntsen, Henrik Hårdensson; Skoglund, Helge; Solem, Øyvind; Sægrov, Harald; Ugedal, Ola (HydroCen Rapport;28, Research report, 2022)
      Utviklingen innenfor genetiske verktøy gir nye muligheter innen miljøovervåkning. Formålet med undersøkelsene i denne rapporten er å vurdere hvordan ulike faktorer kan påvirke estimater av effektiv be-standsstørrelse. ...

    • Hydropower impacts on reservoir fish populations are modified by environmental variation 

      Eloranta, Antti; Finstad, Anders Gravbrøt; Helland, Ingeborg Palm; Ugedal, Ola; Power, Michael (Journal article; Peer reviewed, 2018)
      Global transition towards renewable energy production has increased the demand for newand more flexible hydropower operations. Beforemanagement and stakeholders can make informed choices on potential mitigations, it is ...

    • Interactions between local population density and limited habitat resources determine movements of juvenile Atlantic salmon 

      Teichert, Maxim; Foldvik, Anders; Einum, Sigurd; Finstad, Anders Gravbrøt; Forseth, Torbjørn; Ugedal, Ola (Journal article; Peer reviewed, 2017)
      Competition for limited resources and the resulting density-dependent processes are key factors in driving stream salmonid population dynamics. Here we test for the combined effects of density and shelter availability on ...

    • Modeling salmon lice effects on sea trout population dynamics using an individual-based approach 

      Hedger, Richard David; Diserud, Ola Håvard; Finstad, Bengt; Jensen, Arne Johan; Hendrichsen, Ditte Katrine; Ugedal, Ola; Næsje, Tor (Peer reviewed; Journal article, 2021)
      Salmon lice Lepeophtheirus salmonis infestation of sea trout Salmo trutta results in both additional marine mortality and behavioral changes which may contribute to sea trout population decline. For effective management ...

    • Modelling climate change effects on Atlantic salmon: Implications for mitigation in regulated rivers 

      Sundt-Hansen, Line Elisabeth Breivik; Hedger, Richard David; Ugedal, Ola; Diserud, Ola Håvard; Finstad, Anders Gravbrøt; Sauterleute, Julian Friedrich; Tøfte, Lena S; Alfredsen, Knut; Forseth, Torbjørn (Journal article; Peer reviewed, 2018)
      Climate change is expected to alter future temperature and discharge regimes of rivers. These regimes have a strong influence on the life history of most aquatic river species, and are key variables controlling the growth ...

    • Ontogenetic timing of density dependence: location-specific patterns reflect distribution of a limiting resource 

      Teichert, Maxim; Einum, Sigurd; Finstad, Anders Gravbrøt; Ugedal, Ola; Forseth, Torbjørn (Journal article; Peer reviewed, 2013)
      Theoretical considerations suggest that the relative abundance of age-specific limiting resources determines the ontogenetic timing of density dependence. Structural shelters may represent one such resource which can become ...

    • Salmon louse infestation in wild brown trout populations generates multi-modal mixture distributions 

      Diserud, Ola Håvard; Hedger, Richard David; Finstad, Bengt; Hendrichsen, Ditte Katrine; Jensen, Arne Johan; Ugedal, Ola (Peer reviewed; Journal article, 2020)
      For successful evaluation of the overall effects of salmon louse infestation on brown trout population dynamics, it is crucial to have a realistic understanding of how lice infestation distributions are generated and how ...

    • Utfall av Trollheim kraftverk i juli 2008 - Effekter av fiskebestandene i Surna 

      Forseth, Torbjørn; Stickler, Morten; Ugedal, Ola; Sundt, Håkon; Bremset, Gunnbjørn; Linnansaari, Tommi; Hvidsten, Nils Arne; Harby, Atle; Bongard, Terje; Alfredsen, Knut (NINA Rapport;435, Research report, 2009)
      An accidental stop in the turbine in the Trollheim Hydropower Plant on 27th July 2008 caused a drop in downstream discharge in the River Surna from 21 to 3 m3/s during 100 min. River discharge was reestablished after ...