Browsing NINA Brage by Author "Hedger, Richard David"

Now showing items 1-14 of 14

    • Automated fluvial hydromorphology mapping from airborne remote sensing 

      Hedger, Richard David; Gosselin, Marie-Pierre (Peer reviewed; Journal article, 2023)
      Mapping fluvial hydromorphology is an important part of defining river habitat. Mappingvia field sampling or hydraulic modelingis however time consuming, and mappinghydromorphology directly from remote sensing data may ...

    • Automatisk posisjonering av akustisk merket smolt i tre dimensjoner – utprøving og evaluering i Mandalsvassdraget. 

      Gjelland, Karl Øystein; Baktoft, Henrik; Økland, Finn; Hedger, Richard David; Forseth, Torbjørn (NINA rapport;1072, Research report, 2014)
      Et nytt system som kan gi tredimensjonal (3D) posisjonering av smolt ved hjelp av trådløs akustisk telemetri ble utprøvd og evaluert i Mandalsvassdraget sommeren 2014. I forsøkene ble signaler fra akustiske merker logget ...

    • Bias in estimates of electrofishing capture probability of juvenile Atlantic salmon 

      Hedger, Richard David; Diserud, Ola Håvard; Sandlund, Odd Terje; Saksgård, Laila M.; Ugedal, Ola; Bremset, Gunnbjørn (Journal article; Peer reviewed, 2018)
      We evaluated the effect of the total number of passes used, and the application of block nets, on multi-pass electrofishing removal sampling for estimating juvenile Atlantic salmon (Salmo salar L.) abundance and body size ...

    • Effects of salmon lice infection on the behaviour of sea trout in the marine phase 

      Gjelland, Karl Øystein; Serra-Llinares, Rosa Maria; Hedger, Richard David; Arechavala-Lopez, Pablo; Nilsen, Rune; Finstad, Bengt; Uglem, Ingebrigt; Skilbrei, Ove Tommy; Bjørn, Pål Arne (Peer reviewed, 2014)
      Salmon lice Lepeophtheirus salmonis Krøyer may affect survival and growth of anadromous salmonids through physiological stress and/or behavioural changes. Using acoustic telemetry tracking, we investigated the behaviour ...

    • Heart rate and swimming activity as stress indicators for Atlantic salmon (Salmo salar) 

      Svendsen, Eirik; Føre, Martin; Økland, Finn; Gräns, Albin; Hedger, Richard David; Alfredsen, Jo Arve; Uglem, Ingebrigt; Rosten, Carolyn; Frank, Kevin; Erikson, Ulf Gøran; Finstad, Bengt (Peer reviewed; Journal article, 2020)
      We investigated the relationship between telemetry measurements of heart rate and swimming activity and the physiological status in farmed Atlantic salmon (Salmo salar) to assess the potential to use telemetry measurements ...

    • Ice-dependent winter survival of juvenile Atlantic salmon 

      Hedger, Richard David; Næsje, Tor; Fiske, Peder; Ugedal, Ola; Finstad, Anders Gravbrøt; Thorstad, Eva Bonsak (Peer reviewed; Journal article, 2013)
      Changes in snow and ice conditions are some of the most distinctive impactsof global warming in cold temperate and Arctic regions, altering the environ-ment during a critical period for survival for most animals. Laboratories ...

    • Laks i framtidens klima: Kunnskapsoppsummering og scenario med vekt på temperatur og vannføring 

      Hedger, Richard David; Jonsson, Bror; Kvambekk, Ånund Sigurd; Ekker, Ragnar; Forseth, Torbjørn; Ugedal, Ola; Sundt-Hansen, Line Elisabeth Breivik; Diserud, Ola Håvard (NINA rapport;646, Research report, 2010)
      Finstad, A.G., Hedger, R., Jonsson, B., Kvambekk, Å.S, Ekker, R., Forseth, T., Ugedal, O., Sundt-Hansen, L. & Diserud, O.H. 2010 Laks i framtidens klima: Kunnskapsoppsummering og scenario med vekt på temperatur og ...

    • 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 G.; Sauterleute, Julian Friedrich; Tøfte, Lena S.; Alfredsen, Knut; Forseth, Torbjørn (Peer reviewed; Journal article, 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 ...

    • Modelling the downstream longitudinal effects of frequent hydropeaking on the spawning potential and stranding susceptibility of salmonids 

      Burman, Anton; Hedger, Richard David; Hellstrom, J Gunnar I; Andersson, Anders G; Sundt-Hansen, Line Elisabeth Breivik (Peer reviewed; Journal article, 2021)
      Hydropower plant operating conditions are expected to change to be more in tandem with intermittent power production so as to meet the requirements of the Paris Agreement, which in turn may negatively impact ecolog- ical ...

    • Modelling the effect of hydropeaking‐induced stranding mortality on Atlantic salmon population abundance 

      Hedger, Richard David; Sauterleute, Julian Friedrich; Sundt-Hansen, Line Elisabeth Breivik; Forseth, Torbjørn; Ugedal, Ola; Diserud, Ola Håvard; Bakken, Tor Haakon (Journal article; Peer reviewed, 2018)
      Studies of hydropeaking‐induced stranding mortality on fish populations have been confined to analysis of empirical data and/or short‐term hydraulic‐habitat modelling of individual events and are thus limited as to how ...

    • Redefining the oceanic distribution of Atlantic salmon 

      Rikardsen, Audun H.; Righton, David; Strøm, John Fredrik; Thorstad, Eva Bonsak; Gargan, Patrick G.; Sheehan, Timothy F.; Økland, Finn; Chittenden, Cedar; Hedger, Richard David; Næsje, Tor; Renkawitz, Mark; Sturlaugsson, Johannes; Caballero, Pablo; Baktoft, Henrik; Davidsen, Jan Grimsrud; Halttunen, Elina; Wright, Serena; Finstad, Bengt; Aarestrup, Kim (Peer reviewed; Journal article, 2021)
      Determining the mechanisms driving range-wide reductions in Atlantic salmon marine survival is hindered by an insufcient understanding of their oceanic ecology and distribution. We attached 204 pop-up satellite archival ...

    • Revealing the full ocean migration of individual Atlantic salmon 

      Strøm, John Fredrik; Thorstad, Eva Bonsak; Hedger, Richard David; Rikardsen, Audun H. (Journal article; Peer reviewed, 2018)
      Knowledge of the complete horizontal migration and vertical movements of Atlantic salmon (Salmo salar L.) during the marine phase is important for understanding the link between individual processes and population recruitment. ...

    • 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 ...

    • The effects of hydrodynamics on the three-dimensional downstream migratory movement of Atlantic salmon 

      Silva, Ana T.; Bærum, Kim Magnus; Hedger, Richard David; Baktoft, Henrik; Fjeldstad, Hans-Petter; Gjelland, Karl Øystein; Økland, Finn; Forseth, Torbjørn (Journal article; Peer reviewed, 2019)
      Anthropogenic structures in rivers are major threats for fish migration and effective mitigation is imperative given the worldwide expansion of such structures. Fish behaviour is strongly influenced by hydrodynamics, but ...