Browsing NTNU Open by Author "Hedger, Richard David"

Now showing items 1-13 of 13

    • Exploring sensitivities to hydropeaking in Atlantic salmon parr using individual-based modelling 

      Hedger, Richard David; Sundt-Hansen, Line Elisabeth Breivik; Juarez-Gomez, Ana; Alfredsen, Knut Tore; Foldvik, Anders (Peer reviewed; Journal article, 2023)
      Hydropeaking (the release of water pulses at hydropower plants) results in temporaryreductions in river channel water-covered area downstream, which may cause fishmortality through stranding. We used a mechanistic modelling ...

    • Heart rate and swimming activity as indicators of post-surgical recovery time of Atlantic salmon (Salmo salar) 

      Føre, Martin; Svendsen, Eirik; Økland, Finn; Gräns, Albin; Alfredsen, Jo Arve; Finstad, Bengt; Hedger, Richard David; Uglem, Ingebrigt (Peer reviewed; Journal article, 2021)
      Background Fish telemetry using electronic transmitter or data storage tags has become a common method for studying free-swimming fish both in the wild and in aquaculture. However, fish used in telemetry studies must be ...

    • 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 ...

    • Identification of salmon population bottlenecks from low flows in a hydro-regulated river 

      Adeva Bustos, Ana; Hedger, Richard David; Fjeldstad, Hans-Petter; Stickler, Morten; Alfredsen, Knut (Journal article; Peer reviewed, 2019)
      Flow regime alterations from hydropower regulation may impact fish populations. Impacts can be characterized using methods for mapping bottlenecks for different species life stages. Improving the understanding of such ...

    • Migration and habitat use of the landlocked riverine Atlantic salmon Salmo salar småblank 

      Davidsen, Jan Grimsrud; Eikås, Linda; Hedger, Richard David; Thorstad, Eva Bonsak; Rønning, Lars; Sjursen, Aslak Darre; Berg, Ole Kristian; Bremset, Gunnbjørn; Karlsson, Sten; Sundt-Hansen, Line Elisabeth Breivik (Peer reviewed; Journal article, 2020)
      “Småblank” is the only population of Atlantic salmon in Europe living its entire life in the river habitat without performing migrations to the sea or lakes. Home range size and habitat use were compared between an unregulated ...

    • 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 ...

    • Modeling the effects of alternative mitigation measures on Atlantic salmon production in a regulated river. 

      Adeva Bustos, Ana; Hedger, Richard David; Fjeldstad, Hans-Petter; Alfredsen, Knut; Sundt, Håkon; Barton, David Nicholas (Journal article; Peer reviewed, 2017)
      As part of the investigation of a new and optimized environmental flow regime in a regulated river (Mandalselva, Norway), a modeling study was conducted on the trade-offs between the production of Atlantic salmon (Salmo ...

    • 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 ...

    • Multi-criteria decision analysis in Bayesian networks - diagnosing ecosystem service trade-offs in a hydropower regulated river 

      Barton, David Nicholas; Sundt, Håkon; Adeva Bustos, Ana; Fjeldstad, Hans-Petter; Hedger, Richard David; Forseth, Torbjørn; Köhler, Berit; Aas, Øystein; Alfredsen, Knut; Madsen, Anders L. (Journal article; Peer reviewed, 2019)
      The paper demonstrates the use of Bayesian networks in multicriteria decision analysis (MCDA) of environmental design alternatives for environmental flows (eflows) and physical habitat remediation measures in the Mandalselva ...

    • 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 ...

    • 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 ...

    • Validation of a Swimming Direction Model for the Downstream Migration of Atlantic Salmon Smolts 

      Szabo-Meszaros, Marcell; Silva, Ana T.; Bærum, Kim Magnus; Baktoft, Henrik; Alfredsen, Knut; Hedger, Richard David; Økland, Finn; Gjelland, Karl Øystein; Fjeldstad, Hans-Petter; Calles, Olle; Forseth, Torbjørn (Peer reviewed; Journal article, 2021)
      Fish swimming performance is strongly influenced by flow hydrodynamics, but little is known about the relation between fine-scale fish movements and hydrodynamics based on in-situ investigations. In the presented study, ...

    • Vandringer og habitatbruk til småblank 

      Davidsen, Jan Grimsrud; Eikås, Linda; Hedger, Richard David; Rønning, Lars; Sjursen, Aslak Darre; Thorstad, Eva Bonsak; Berg, Ole Kristian; Bremset, Gunnbjørn; Karlsson, Sten; Sundt-Hansen, Line Elisabeth Breivik (NTNU Vitenskapsmuseet naturhistorisk rapport;, Research report, 2018)
      Småblank er den eneste rent elvelevende laksen i Europa, og finnes kun i øvre deler av Nam-senvassdraget. Størrelsen på bestanden er ukjent, men det er grunn til at tro at bestandstettheten har gått ned siden 1950- tallet, ...