• Contour current driven continental slope-situated sandwaves with effects from secondary current processes on the Barents Sea margin offshore Norway 

      King, Edward L.; Bøe, Reidulv; Bellec, Valérie K.; Rise, Leif Christian; Skardhamar, Jofrid; Ferré, Bénédicte; Dolan, Margaret F.J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-15)
      Seabed data acquired from the southern Barents Sea continental margin offshore Norway reveal detailed morphology of large sandwave fields. Multibeam echosounder bathymetry and backscatter, shallow seismic, sediment samples and seabed video data collected by the MAREANO program have been used to describe and interpret the morphology, distribution and transport of the sandwaves. The bedforms lie on a ...
    • An effective method for the recapture of escaped farmed salmon 

      Chittenden, Cedar; Rikardsen, Audun H.; Skilbrei, Ove Tommy; Davidsen, Jan Grimsrud; Halttunen, Elina; Skardhamar, Jofrid; McKinley, R. Scott (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-04-04)
      The search for effective strategies to prevent and mitigate accidental releases of aquaculture fishes is on-going. To test a new recapture strategy and evaluate the individual dispersal behaviour of escaped farmed Atlantic salmon <i>Salmo salar</i> L. at the northern limit of its range, 39 adult salmon (mean ± SD fork length and weight: 85.5 ± 5.0 cm and 7.4 ± 1.4 kg, respectively) were implanted ...
    • Effects of mortality changes on biomass and production in Calanus spp. populations 

      Skardhamar, Jofrid; Reigstad, Marit; Carroll, Jolynn; Eiane, Ketil; Wexels Riser, Christian; Slagstad, Dag (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-04-28)
      Calanus species are the main link between primary producers and higher trophic-level organisms in the Barents Sea. The natural mortality rate is an essential parameter for determining the standing stock of Calanus, but it is also one of the most uncertain parameters in present knowledge. The level of human activity, and the associated risk of pollution, is increasing in the Barents Sea, and knowledge ...
    • From above and standing atop- two views of Norwegian fjord ice 

      O'Sadnick, Megan; Petrich, Chris; Brekke, Camilla; Skardhamar, Jofrid (Conference object; Konferansebidrag, 2020-10)
      In O’Sadnick et al. (2020), estimations of ice extent along the coast of Norway since 2001 determined from MODIS imagery are presented. From our findings, it is evident that the amount of ice in one fjord over time often varies and shows little consistency leading to the next question of ‘Why’? The study continues to relate freezing degree days, rainfall plus snowmelt, and snowfall to values of ...
    • Homing behaviour of Atlantic salmon (Salmo salar) during final phase of marine migration and river entry 

      Davidsen, Jan Grimsrud; Rikardsen, Audun H.; Thorstad, Eva Bonsak; Halttunen, Elina; Mitamura, Hiromichi; Præbel, Kim; Skardhamar, Jofrid; Næsje, Tor (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Little is known about Atlantic salmon behaviour during the last phase of the marine homing migration and subsequent river entry. In this study, 56 adult Atlantic salmon in the Alta Fjord in northern Norway were equipped with acoustic transmitters. Salmon generally followed the coastline, but their horizontal distribution was also affected by wind-induced spreading of river water across the fjord. ...
    • Ice conditions in northern Norwegian fjords: Observations and measurements from three winter seasons, 2017–2020 

      O'Sadnick, Megan; Petrich, Chris; Brekke, Camilla; Skardhamar, Jofrid; Kleven, Øystein (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-31)
      Freshwater provided by rivers beginning deep within the mountains, feeds into fjords along the coast of Norway, often forming a brackish surface layer that will change in its salinity, thickness, and extent throughout the year. As temperature drops below freezing, ice can form from this layer along the entire coastline from 71◦ N down to 58◦ N. The influence of freshwater combined with changing ...
    • Ice extent in sub-arctic fjords and coastal areas from 2001 to 2019 analyzed from MODIS imagery 

      O'Sadnick, Megan Eileen; Petrich, Chris; Brekke, Camilla; Skardhamar, Jofrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-03)
      Results examining variations in the ice extent along the Norwegian coastline based on the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) images from 2001 to 2019, February through May, are presented. A total of 386 fjords and coastal areas were outlined and grouped into ten regions to assess seasonal and long-term trends in ice extent. In addition, three fjords were examined to ...
    • Micro- and macro-habitat selection of Atlantic salmon, (Salmo salar), post-smolts in relation to marine environmental cues 

      Jensen, Jenny Lovisa Alexandra; Strøm, John Fredrik; Nikolopoulos, Anna; Primicerio, Raul; Skardhamar, Jofrid; Atencio, Benjamin J.; Strand, Jo Espen Tau; Bjørn, Pål Arne; Bøhn, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-20)
      Atlantic salmon is an economically and culturally important species. The species encounters several natural and man-made threats during its migration between fresh water and the ocean, which in combination may explain its ongoing decline. With the aim to better understand whether post-smolt behaviour is influenced by physical oceanographic conditions, the migratory behaviour of 173 post-smolts in a ...
    • Migratory behaviour and survival rates of wild northern Atlantic salmon (Salmo salar) post-smolts: effects of environmental factors 

      Thorstad, EB; Davidsen, Jan Grimsrud; Økland, F.; Rikardsen, Audun H.; Halttunen, Elina; Letcher, B.H,; Skardhamar, Jofrid; Næsje, Tor (Journal article; Tidsskriftartikkel; Peer reviewed, 2009-12-03)
      To study smolt behaviour and survival of a northern Atlantic salmon (Salmo salar) population during river descent, sea entry and fjord migration, 120 wild S. salar were tagged with acoustic tags and registered at four automatic listening station arrays in the mouth of the North Norwegian River Alta and throughout the Alta Fjord. An estimated 75% of the post-smolts survived from the river mouth, ...
    • Migratory behaviour and survival rates of wild northern Atlantic salmon Salmo salar post-smolts: effects of environmental factors 

      Thorstad, EB; Davidsen, Jan Grimsrud; Økland, F.; Rikardsen, Audun H.; Halttunen, Elina; Letcher, B.H,; Næsje, Tor; Skardhamar, Jofrid (Conference object; Konferansebidrag, 2009-09-14)
    • Modelled drift patterns of fish larvae link coastal morphology to seabird colony distribution 

      Sandvik, Hanno; Barrett, Robert T.; Erikstad, Kjell E; Myksvoll, Mari Skuggedal; Vikebø, Frode Bendiksen; Yoccoz, Nigel Gilles; Anker-Nilssen, Tycho; Lorentsen, Svein-Håkon; Reiertsen, Tone; Skardhamar, Jofrid; Skern-Mauritzen, Mette; Systad, Geir Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-13)
      Colonial breeding is an evolutionary puzzle, as the benefits of breeding in high densities are still not fully explained. Although the dynamics of existing colonies are increasingly understood, few studies have addressed the initial formation of colonies, and empirical tests are rare. Using a high-resolution larval drift model, we here document that the distribution of seabird colonies along the ...
    • Pelagic ecosystem dynamics between late autumn and the post spring bloom in a sub-Arctic fjord 

      Walker, Emily-Zoe Elizabeth; Wiedmann, Ingrid; Nikolopoulos, Anna; Skardhamar, Jofrid; Jones, Elizabeth Marie; Renner, Angelika (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-13)
      Marine ecosystems, and particularly fjords, are experiencing an increasing level of human activity on a yearround basis, including the poorly studied winter period. To improve the knowledge base for environmentally sustainable management in all seasons, this study provides hydrographic and biological baseline data for the sub-Arctic fjord Kaldfjorden, Northern Norway (69.7 N, 18.7 E), between ...
    • Sampling planktonic salmon lice in Norwegian fjords 

      Skardhamar, Jofrid; Fagerli, Margrethe Nilsen; Reigstad, Marit; Sandvik, Anne Dagrun; Bjørn, Pål Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-19)
      Risk of mortality of wild salmon caused by salmon lice is used as an index for managing aquaculture production in Norway and is based on monitoring of lice attached to wild salmonids and modelled concentrations of lice larvae in fjords. Direct sampling of lice from Norwegian waters to determine concentrations has never been published scientifically and has been considered non-feasible for monitoring ...
    • Sea trout adapt their migratory behaviour in response to high salmon lice concentrations 

      Halttunen, Elina; Gjelland, Karl Øystein; Hamel, Sandra; Serra-Llinares, Rosa Maria; Nilsen, Rune; Arechavala-Lopez, Pablo; Skardhamar, Jofrid; Asplin, Lars; Karlsen, Ørjan; Bjørn, Pål Arne; Finstad, Bengt (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-21)
      Sea trout face growth–mortality trade-offs when entering the sea to feed. Salmon lice epizootics resulting from aquaculture have shifted these trade-offs, as salmon lice might both increase mortality and reduce growth of sea trout. We studied mortality and behavioural adaptations of wild sea trout in a large-scale experiment with acoustic telemetry in an aquaculture intensive area that was fallowed ...
    • Tracking changes in the fjord environment over a winter season using ice bulk salinity and δ18O 

      O'Sadnick, Megan; Petrich, Chris; Skardhamar, Jofrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-11)
      Ice that forms in the fjords of northern Norway often undergoes temperature fluctuations, rising above and below freezing, throughout winter and experiences variable conditions at the ice-ocean interface due to changes in freshwater runoff from surrounding land. Conditions at the interface can be difficult to track throughout the season without consistent measurement, resultantly limiting ...