Browsing Bergen Open Research Archive by Author "Hansen, Tom Johnny"

Now showing items 1-20 of 25

    • Atlantic salmon male post-smolt maturation can be reduced by using a 3-hour scotophase when inducing smoltification 

      Fraser, Thomas; Hansen, Tom Johnny; Norberg, Birgitta; Nilsen, Tom Ole; Schulz, Rüdiger W.; Fjelldal, Per Gunnar (Journal article; Peer reviewed, 2023)
      Photoperiod regulates the occurrence of unwanted male post-smolt maturation during the production of large (>100 g) Atlantic salmon (Salmo salar) smolts. However, the optimal daylength for triggering smoltification, but ...

    • Autosomal sdY pseudogenes explain discordances between phenotypic sex and DNA marker for sex identification in Atlantic salmon 

      Ayllon, Fernando; Solberg, Monica Favnebøe; Besnier, Francois; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Wargelius, Anna; Edvardsen, Rolf Brudvik; Glover, Kevin (Journal article; Peer reviewed, 2020)
      Despite the key role that sex-determination plays in evolutionary processes, it is still poorly understood in many species. In salmonids, which are among the best studied fishes, the master sex-determining gene sexually ...

    • Blue mussel (Mytilus edulis) silage, a possible low trophic marine protein source for Atlantic salmon (Salmo salar L.) 

      Sartipiyarahmadi, Sahar; Philip, Antony Jesu Prabhu; Forshei, Aksel N.; Sveier, Harald; Steinsund, Silje; Kleppe, Malin; Lock, Erik Jan Robert; Madaro, Angelico; Hansen, Tom Johnny; Strand, Øivind; Wiech, Martin; Jakobsen, Jan Vidar; Remø, Sofie C. (Journal article; Peer reviewed, 2024)
      Blue mussel (Mytilus edulis) could be a promising marine protein source in fish feeds and is of great interest since it can be cultivated along the Norwegian coastline. However, the use of blue mussels in feeds is dependent ...

    • Changes in water temperature and oxygen: the effect of triploidy on performance and metabolism in large farmed Atlantic salmon 

      Sambraus, Florian; Remen, Mette; Olsen, Rolf Erik; Hansen, Tom Johnny; Waagbø, Rune; Torgersen, Thomas; Lock, Erik-Jan; Imsland, Albert; Fraser, Thomas W.K.; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2018)
      In salmon farming, the use of sterile triploids (3N) can mitigate the problem of escapees interbreeding with wild salmon. However, triploid salmon appear less tolerant to high water temperatures and low oxygen levels ...

    • Chromosome aberrations in pressureinduced triploid Atlantic salmon 

      Glover, Kevin; Harvey, Alison C.; Hansen, Tom Johnny; Fjelldal, Per Gunnar; Besnier, Francois; Bos, J.B.; Ayllon, Fernando; Taggart, John B.; Solberg, Monica Favnebøe (Journal article; Peer reviewed, 2020)
      Background Triploid organisms have three sets of chromosomes. In Atlantic salmon, hydrostatic pressure treatment of newly fertilized eggs has been extensively used to produce triploids which are functionally sterile due ...

    • Cloned and outbred Atlantic salmon display equal parasite dispersion when infected with the salmon louse 

      Glover, Kevin; Hansen, Tom Johnny; Besnier, Francois; Solberg, Monica Favnebøe; Fjelldal, Per Gunnar; Sørvik, Anne Grete Eide; Dalvin, Sussie; Nilsen, Frank (Peer reviewed; Journal article, 2017-11)
      The salmon louse is an ectoparasitic copepod that infects salmonids in the marine environment. This parasite causes a major economic and biological challenge to the Atlantic salmon farming industry, and efforts to increase ...

    • Comparing physiological responses of acute and chronically stressed diploid and triploid Atlantic salmon (Salmo salar) 

      Madaro, Angelico; Lai, Floriana; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Gelebart, Virginie; Muren, Brynjar; Rønnestad, Ivar; Olsen, Rolf-Erik; Stien, Lars Helge (Journal article; Peer reviewed, 2024)
      We compared the performance and physiological response of diploid and triploid Atlantic salmon (Salmo salar) following 21 days of either unpredictable chronic stress (UCS) or no disturbance (control). Thereafter, all four ...

    • The Distribution of IgT mRNA+ Cells in the Gut of the Atlantic Salmon (Salmo salar L.) 

      Castro, Pedro Luis; Barac, Fran; Hansen, Tom Johnny; Fjelldal, Per Gunnar; Hordvik, Ivar; Bjørgen, Håvard; Koppang, Erling Olaf (Journal article; Peer reviewed, 2023)
      The newly discovered IgT+ B cell is thought to play a dominant role in mucosal immunity, but limited studies have examined its distribution in fish species, hindering our understanding of its function. This study investigated ...

    • A genetic method to infer ploidy and aberrant inheritance in triploid organisms 

      Delaval, Aurelien Nicolas; Glover, Kevin Alan; Solberg, Monica Favnebøe; Taggart, John B.; Besnier, Francois; Sørvik, Anne Grete Eide; Øyro, Johanne; Garnes-Gutvik, Sofie Nordaune; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Harvey, Alison C. (Journal article; Peer reviewed, 2024)
      Polyploidy occurs naturally across eukaryotic lineages and has been harnessed in the domestication of many crops and vertebrates. In aquaculture, triploidy can be induced as a biocontainment strategy, as it creates a ...

    • Growth Performance, Nutrient Digestibility, and Retention in Atlantic Salmon, Salmo salar L., Fed Diets with Fermented Sugar Kelp, Saccharina latissima 

      Sartipiyarahmadi, Sahar; Philip, Antony Jesu Prabhu; Sveier, Harald; Steinsund, Silje; Lock, Erik Jan Robert; Madaro, Angelico; Hansen, Tom Johnny; Wiech, Martin; Strand, Øivind; Jakobsen, Jan Vidar; Van Der Heide, Marleen E.; Nørgaard, Jan Værum; Remø, Sofie C. (Journal article; Peer reviewed, 2023)
      Using low trophic marine resources such as sugar kelp (Saccharina latissimi) is of great interest to increase the circular food production in the ocean. Sugar kelp does, however, contain high levels of carbohydrates and ...

    • Impact of Antioxidant Feed and Growth Manipulation on the Redox Regulation of Atlantic Salmon Smolts 

      Yin, Peng; Bjørnsson, Bjørn Thrandur; Fjelldal, Per Gunnar; Saito, Takaya; Remø, Sofie C.; Edvardsen, Rolf Brudvik; Hansen, Tom Johnny; Sharma, Sandeep; Olsen, Rolf Erik; Hamre, Kristin (Journal article; Peer reviewed, 2022-08-30)
      Accumulating evidence indicates a close relationship between oxidative stress and growth rate in fish. However, the underlying mechanisms of this relationship remain unclear. This study evaluated the combined effect of ...

    • The influence of vgll3 genotypes on sea age at maturity is altered in farmed mowi strain Atlantic salmon 

      Ayllon, Fernando; Solberg, Monica Favnebøe; Glover, Kevin; Mohammadi, Faezeh; Kjærner-Semb, Erik Nordtorp; Fjelldal, Per Gunnar; Andersson, Eva; Hansen, Tom Johnny; Edvardsen, Rolf; Wargelius, Anna (Peer reviewed; Journal article, 2019-05-06)
      Background: In Atlantic salmon in the wild, age at maturity is strongly influenced by the vgll3 locus. Under farming conditions, light, temperature and feeding regimes are known significantly advance or delay age at maturity. ...

    • A new method for regionalization of the vertebral column in salmonids based on radiographic hallmarks 

      Murugesan, Sankar; Kryvi, Harald; Fraser, Thomas; Philip, Antony Jesu Prabhu; Remø, Sofie C.; Hansen, Tom Johnny; Witten, Paul Eckhard; Fjelldal, Per Gunnar (Journal article; Peer reviewed, 2024)
      Current procedures to establish vertebral column regionalization (e.g., histology) in fish are time consuming and difficult to apply. The aim of this study was to develop a more rapid and accurate radiology-based method ...

    • No environmental effect on vaccine-induced reduced growth in Atlantic salmon Salmo salar smolts 

      Fraser, Thomas; Fjelldal, Per Gunnar; Sommerset, Ingunn; Søfteland, Tina; Høstmark, Ole; Powell, Mark; Heen, Vegar; Hansen, Tom Johnny (Journal article; Peer reviewed, 2020)
      Oil-adjuvanted vaccines reduce long-term growth in farmed Atlantic salmon Salmo salar, possibly via an increase in metabolic rate due to the energetic demands of the immune system. We tested this hypothesis by comparing ...

    • Organisation of the Atlantic salmon (Salmo salar) thymus and its content of Ig-expressing cells 

      Bjørgen, Håvard; Barac, Fran; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Hordvik, Ivar; Koppang, Erling Olaf (Journal article; Peer reviewed, 2024)
      The thymus of fishes is located as a dual organ in a rostrodorsal projection within the gill chamber and is covered by the operculum. The histological organization of the teleost fish thymus displays considerable diversity, ...

    • Ploidy elicits a whole-genome dosage effect: growth of triploid Atlantic salmon is linked to the genetic origin of the second maternal chromosome set 

      Harvey, Alison C.; Fjelldal, Per Gunnar; Solberg, Monica Favnebøe; Hansen, Tom Johnny; Glover, Kevin (Peer reviewed; Journal article, 2017-04-11)
      Background: The Atlantic salmon aquaculture industry is investigating the feasibility of using sterile triploids to mitigate genetic interactions with wild conspecifics, however, studies investigating diploid and triploid ...

    • Production and verification of the first Atlantic salmon (Salmo salar L.) clonal lines 

      Hansen, Tom Johnny; Penman, David J.; Glover, Kevin; Fraser, Thomas; Vågseth, Tone; Thorsen, Anders; Sørvik, Anne Grete Eide; Fjelldal, Per Gunnar (Journal article; Peer reviewed, 2020)
      Background In several fish species homozygous and heterozygous clonal lines have been produced using gynogenetic and androgenetic techniques. These lines are standardized and can be reproduced over generations. In rainbow ...

    • Seasonal Changes in Photoperiod: Effects on Growth and Redox Signaling Patterns in Atlantic Salmon Postsmolts 

      Yin, Peng; Saito, Takaya; Fjelldal, Per Gunnar; Björnsson, Björn Thrandur; Remø, Sofie C.; Hansen, Tom Johnny; Sharma, Sandeep; Olsen, Rolf-Erik; Hamre, Kristin (Journal article; Peer reviewed, 2023)
      Farmed Atlantic salmon reared under natural seasonal changes in sea-cages had an elevated consumption of antioxidants during spring. It is, however, unclear if this response was caused by the increase in day length, ...

    • Sequence of formation and inheritance of meristic variation in the post-cranial axial skeleton of Atlantic salmon (Salmo salar) 

      Philip, Antony Jesu Prabhu; Fraser, Thomas; Nordvik, Kari; Remø, Sofie C.; Hansen, Tom Johnny; Witten, Paul Eckhard; Kryvi, Harald; Fjelldal, Per Gunnar (Journal article; Peer reviewed, 2025)
      Atlantic salmon is an important aquaculture species that has fascinated naturalists for centuries, resulting in its biology being widely characterized. Certain details about the early development and the inheritance of ...

    • A transcriptomic analysis of diploid and triploid Atlantic salmon lenses with and without cataracts 

      Olsvik, Pål Asgeir; Finn, Roderick Nigel; Remø, Sofie C.; Fjelldal, Per Gunnar; Chauvigné, Francois; Glover, Kevin; Hansen, Tom Johnny; Waagbø, Rune (Journal article; Peer reviewed, 2020)
      To avoid negative environmental impacts of escapees and potential inter-breeding with wild populations, the Atlantic salmon farming industry has and continues to extensively test triploid fish that are sterile. However, ...