• Behaviour and mortality of downstream migrating Atlantic salmon smolts at a small power station with multiple migration routes 

      Kärgenberg, Einar; Thorstad, Eva Bonsak; Järvekülg, Rein; Sandlund, Odd Terje; Saadre, Ene; Økland, Finn; Thalfeldt, Mart; Tambets, Meelis (Journal article; Peer reviewed, 2019)
      Salmon smolts were released upstream of a run‐of‐river hydropower site and recaptured downstream for inspection. Descending fish behaviour through three possible migration routes (turbines, fishway, spillway) was analysed ...
    • Biotic and abiotic determinants of the ascent behaviour of adult Atlantic salmon transiting passable waterfalls 

      Lennox, Robert J.; Thorstad, Eva Bonsak; Diserud, Ola Håvard; Økland, Finn; Cooke, Steven J.; Aasestad, Ingar; Forseth, Torbjørn (Journal article; Peer reviewed, 2018)
      The spawning migration of Atlantic salmon has been characterized by tracking salmon carrying electronic tags as they ascend rivers, but still little is known about how natural obstacles such as waterfalls influence migratory ...
    • Effects of a dispersal barrier on freshwater migration of the vimba bream (Vimba vimba) 

      Tambets, Meelis; Kärgenberg, Einar; Thorstad, Eva Bonsak; Sandlund, Odd Terje; Økland, Finn; Thalfeldt, Mart (Journal article; Peer reviewed, 2018)
      To study the effects of a dispersal barrier on migration of the semi-anadromous vimba bream in the Pärnu River, Estonia, we tagged thirty fish with acoustic transmitters and released above the barrier. Tagged fish showed ...
    • Empirical observations of the spawning migrationof European eels: The long and dangerous roadto the Sargasso Sea 

      Righton, David; Westerberg, Håkan; Feunteun, Eric; Økland, Finn; Gargan, Patrick G.; Amilhat, Elsa; Metcalfe, Julian; Lobon-Cervia, Javier; Sjöberg, Niklas; Simon, Janek; Acou, Anthony; Vedor, Marisa; Walker, Alan; Trancart, Thomas; Brämick, Uwe; Aarestrup, Kim (Journal article; Peer reviewed, 2016)
      The spawning migration of the European eel (Anguilla anguilla L.) to the Sargasso Sea is one of the greatest animal migrations. However, the duration and route of the migration remain uncertain. Using fishery data from ...
    • Escaped farmed Atlantic salmon in Norwegian rivers during 1989–2013 

      Diserud, Ola Håvard; Fiske, Peder; Sægrov, Harald; Urdal, K.; Aronsen, Tonje; Lo, Håvard; Barlaup, Bjørn Torgeir; Niemela, Eero; Orell, P.; Erkinaro, J.; Lund, Roar A.; Økland, Finn; Østborg, Gunnel Marie; Hansen, Lars Petter; Hindar, Kjetil (Journal article; Peer reviewed, 2019)
      We report on the data from an extensive monitoring programme for the occurrence of escaped farmed Atlantic salmon (Salmo salar) in Norwegian rivers for 25 years. This monitoring started as a 3-year research programme in ...
    • European eel Anguilla anguilla compromise speed for safety in the early marine spawning migration 

      Lennox, Robert J.; Økland, Finn; Mitamura, Hiromichi; Cooke, Steven J.; Thorstad, Eva Bonsak (Journal article; Peer reviewed, 2018)
      There are substantial benefits to potential fitness conferred to animals that undertake migrations. However, animals must make compromises to maximize survival and compensate for the risks associated with long-distance ...
    • Impacts of a weir and power station on downstream migrating Atlantic salmon smolts in a German river 

      Havn, Torgeir Børresen; Thorstad, Eva Bonsak; Borcherding, Jost; Heermann, Lisa; Teichert, Maxim A. K.; Ingendahl, Detlev; Tambets, Meelis; Sæther, Stein Are; Økland, Finn (Peer reviewed; Journal article, 2020)
      Weirs are barriers built across rivers for a wide range of other purposes than hydropower production. Like hydropower installations, weirs can negatively impact fish migrations. Downstream migration and mortality of Atlantic ...
    • In situ measurement of salinity during seaward migration of Atlantic salmon post‑smolts using acoustic transmitters with data‑storage capabilities and conventional acoustic transmitters 

      Mitamura, Hiromichi; Thorstad, Eva Bonsak; Uglem, Ingebrigt; Økland, Finn (Journal article; Peer reviewed, 2017)
      Background: Development of miniature acoustic transmitters and data-storage tags has provided new insights into ecology of free-ranging aquatic animals. In this study, we used a data-storage-type and a conventional acoustic ...
    • Movements of dead fish in rivers 

      Havn, Torgeir Børresen; Økland, Finn; Teichert, Maxim A.K.; Heermann, L.; Borcherding, J; Sæther, Stein Are; Tambets, M.; Diserud, Ola Håvard; Thorstad, Eva Bonsak (Journal article; Peer reviewed, 2017)
      Background: The aim of telemetry studies is often to determine the fate and mortality rates of ish. A moving ish is usually regarded as alive and a long-term stationary ish as dead—and the site where it became stationary ...
    • Positioning of aquatic animals based on time-of-arrival and random walk models using YAPS (Yet Another Positioning Solver) 

      Baktoft, Henrik; Gjelland, Karl Øystein; Økland, Finn; Thygesen, Uffe Høgsbro (Journal article; Peer reviewed, 2017)
      Aquatic positional telemetry offers vast opportunities to study in vivo behaviour of wild animals, but there is room for improvement in the data quality provided by current procedures for estimating positions. Here we ...
    • 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 ...