Browsing Scientific publications by Author "Økland, Finn"
Now showing items 1-20 of 23
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Annual and diel activity cycles of a northern population of the large migratory cyprinid fish asp (Leuciscus aspius)
Kärgenberg, Einar; Sandlund, Odd Terje; Thorstad, Eva Bonsak; Thalfeldt, Mart; Økland, Finn; Kaasik, Ants; Tambets, Meelis (Peer reviewed; Journal article, 2022)Little is known about the exact movement parameters of migratory cyprinids listed as conservation priorities. A northern population of predatory asp, listed on the Bern Convention Appendix III, was studied in a near ... -
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 ... -
Can Energy Depletion of Wild Atlantic Salmon Kelts Negotiating Hydropower Facilities Lead to Reduced Survival?
Baktoft, Henrik; Gjelland, Karl Øystein; Szabo-Meszaros, Marcell; Silva, Ana T.; Riha, Milan; Økland, Finn; Alfredsen, Knut; Forseth, Torbjørn (Peer reviewed; Journal article, 2020)Repeat spawners constitute an important component of Atlantic salmon populations, but survival of post-spawning individuals (kelts) are often compromised by anthropogenic structures such as hydropower plants (HPPs). Potential ... -
Comparing dominance relationships and movement of native marble trout (Salmo marmoratus) and introduced rainbow trout (Oncorhynchus mykiss)
Pengal, Polona; Cokan, Blaz; Økland, Finn; Höjesjö, Johan; Tambets, Meelis; Thorstad, Eva Bonsak (Peer reviewed; Journal article, 2023) -
Contrasting structural complexity diferentiate hunting strategy in an ambush apex predator
Říha, Milan; Gjelland, Karl Øystein; Děd, Vilém; Eloranta, Antti; Rabaneda-Bueno, Ruben; Baktoft, Henrik; Vejřík, Lukáš; Vejříková, Ivana; Drastik, Vladislav; Šmejkal, Marek; Holubová, Michaela; Jůza, Tomáš; Rosten, Carolyn; Sajdlová, Zuzana; Økland, Finn; Peterka, Jiří (Peer reviewed; Journal article, 2021)Structural complexity is known to influence prey behaviour, mortality and population structure, but the effects on predators have received less attention. We tested whether contrasting structural complexity in two newly ... -
Development and testing of attachment methods for pop-up satellite archival transmitters in European eel
Økland, Finn; Thorstad, Eva Bonsak; Westerberg, Håkan; Aarestrup, Kim; Metcalfe, Julian D. (Peer reviewed, 2013)Background: Four methods for attaching pop-up satellite transmitters to European eel were tested in the laboratory by recording long-term tag retention, growth and survival; short-term behavioral responses; and physical ... -
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 ... -
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 ... -
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 ... -
An Invited Reply to: A Comment on: Migrating silver eels return from the sea to the river of origin after a false start (2021) by Tambets M et al
Tambets, Meelis; Kärgenberg, Einar; Järvalt, Ain; Økland, Finn; Kristensen, Martin Lykke; Koed, Anders; Bernotas, Priit (Peer reviewed; Journal article, 2022) -
Migrating silver eels return from the sea to the river of origin after a false start
Tambets, Meelis; Kärgenberg, Einar; Järvalt, Ain; Økland, Finn; Kristensen, Martin Lykke; Koed, Anders; Bernotas, Priit (Peer reviewed; Journal article, 2021)The European eel’s singular spawning migration from European waters towards the Sargasso Sea remains elusive, including the early phase of migration at sea. During spawning migration, the movement of freshwater resident ... -
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 ... -
Natural and anthropogenic drivers of escaped farmed salmon occurrence and introgression into wild Norwegian Atlantic salmon populations
Diserud, Ola Håvard; Fiske, Peder; Karlsson, Sten; Glover, Kevin Alan; Næsje, Tor; Aronsen, Tonje; Bakke, Gunnar O; Barlaup, Bjørn Torgeir; Erkinaro, J.; Florø-Larsen, Bjørn; Foldvik, Anders; Heino, Mikko Petteri; Kanstad-Hanssen, Øyvind; Lo, Håvard; Lund, Roar Asbjørn; Muladal, R.; Niemela, E.; Økland, Finn; Østborg, Gunnel Marie; Otterå, Håkon Magne; Skaala, Øystein; Skoglund, Helge; Solberg, Ingrid; Solberg, Monica Favnebøe; Sollien, Vegard Pedersen; Sægrov, Harald; Urdal, Kurt; Wennevik, Vidar; Hindar, Kjetil (Peer reviewed; Journal article, 2022)Marine aquaculture of Atlantic salmon (Salmo salar) is a relatively new industry where breeding programs have led to rapid genetic change in the captive populations that were built up alongside conspecific wild individuals. ... -
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 ... -
Recommendations on size and position of surgically and gastrically implanted electronic tags in European silver eel
Økland, Finn; Thorstad, Eva Bonsak (Peer reviewed; Journal article, 2013)Background: Information on European silver eel Anguilla anguilla anatomy was collected to gain information on limitations on size and placement of electronic tags. Findings: To reduce the eel’s ability to bite its own ...