Browsing Brage IMR by Author "Hansen, Tom Johnny"
Now showing items 41-59 of 59
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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 (Peer reviewed; Journal article, 2020)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 trout such ... -
Red and melanized focal changes in white skeletal muscle in Atlantic salmon (Salmo salar): Comparative analysis of farmed, wild and hybrid fish reared under identical conditions
Brimsholm, Malin Helen; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Fraser, Thomas; Solberg, Monica Favnebøe; Glover, Kevin Alan; Koppang, Erling Olaf; Bjørgen, Håvard (Peer reviewed; Journal article, 2023)Selective breeding plays a vital role in the production of farmed Atlantic salmon and has shown success in many aspects. Still, challenges related to fish health and welfare continue to result in significant economic losses. ... -
Regional and temporal variation in escape history of Norwegian farmed Atlantic salmon
Strand, Nina; Glover, Kevin Alan; Meier, Sonnich; Ayllon, Fernando; Wennevik, Vidar; Madhun, Abdullah Sami; Skaala, Øystein; Hamre, Kristin; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Niemelä, Eero; Knutar, Sofie; Andersen-Fjeldheim, Per Tommy; Solberg, Monica Favnebøe (Peer reviewed; Journal article, 2024)Each year thousands of farmed Atlantic salmon escape from seawater net pens, and introgression has been documented in a range of wild populations. Due to greater experience in the wild, escapees that have been on the run ... -
Salmon lice threaten growth, osmoregulation and survival in anadromous Arctic char post-smolts
Fjelldal, Per Gunnar; Hansen, Tom Johnny; Karlsen, Ørjan; Wright, Daniel William (Peer reviewed; Journal article, 2019)High salmon lice (Lepeophtheirus salmonis) infestation levels resulting from intensive salmonid sea-cage aquaculture can threaten populations of wild salmonid hosts. This includes anadromous Arctic char (Salvelinus alpinus), ... -
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 (Peer reviewed; Journal article, 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, ... -
Sexual maturation and smoltification in domesticated Atlantic salmon (Salmo salar L.) - is there a developmental conflict?
Fjelldal, Per Gunnar; Schulz, Rüdiger W.; Nilsen, Tom Ole; Andersson, Eva; Norberg, Birgitta; Hansen, Tom Johnny (Journal article; Peer reviewed, 2018)We present data from two experiments that examined how the developmental processes of smoltification and sexual maturation proceed in parallel in domesticated Atlantic salmon. Onset of maturation and smoltification was ... -
Spawning manipulation, broodfish diet feeding and egg production in farmed Atlantic salmon
Fjelldal, Per Gunnar; Adam, Anne-Catrin; Berge, Gerd Marit; Lein, Ingrid; Hevrøy, Ernst Morten; Næve, Ingun; Seim, Rudi R.; Mommens, Maren; Skjærven, Kaja Helvik; Hansen, Tom Johnny; Hamre, Kristin (Peer reviewed; Journal article, 2024)Atlantic salmon aquaculture relies on continuous supply of high quality eggs. Broodfish nutrition and manipulation of ovulation time (photoperiod and temperature) are key factors. The optimum feeding period with broodfish ... -
The frequency of spontaneous triploidy in farmedAtlantic salmon produced in Norway during theperiod 2007–2014
Glover, Kevin; Madhun, Abdullah Sami; Dahle, Geir; Sørvik, Anne Grete Eide; Wennevik, Vidar; Skaala, Øystein; Morton, Hugh Craig; Hansen, Tom Johnny; Fjelldal, Per Gunnar (Journal article; Peer reviewed, 2015-04-11)Background: Spontaneous triploidy has been reported in a number of fish species, and is often linked with in vivo or in vitro ageing of eggs post ovulation. Here, we provide the first investigation into the frequency 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 (Journal article; Peer reviewed, 2019)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 ... -
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 (Peer reviewed; Journal article, 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, ... -
Triploid Atlantic salmon and triploid Atlantic salmon × brown trout hybrids have better freshwater and early seawater growth than diploid counterparts
Fraser, Thomas; Lerøy, Hilde; Hansen, Tom Johnny; Skjæraasen, Jon Egil; Tronci, Valentina; Pinto Pedrosa, Cindy; Fjelldal, Per Gunnar; Nilsen, Tom Ole (Peer reviewed; Journal article, 2021)The use of reproductively sterile triploid salmonids would enhance the environmental sustainability of the aquaculture industry by preventing genetic exchange between escapees and wild conspecifics. To this end, we assessed ... -
Triploid Atlantic salmon Salmo salar have a higher dietary phosphorus requirement for bone mineralization during early development
Sambraus, Florian; Hansen, Tom Johnny; Daae, Britt Sværen; Thorsen, Anders; Sandvik, Roar; Stien, Lars Helge; Fraser, Thomas; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2020)The effect of a dietary phosphorus regime in freshwater on vertebra bone mineralization was assessed in diploid and triploid Atlantic salmon, Salmo salar. Fish were fed either a low phosphorus (LP) diet containing 10.5 ... -
Triploid Atlantic salmon × brown trout hybrids have similar seawater growth and welfare issues as triploid Atlantic salmon, but both were heavier at harvest than their diploid counterparts
Fraser, Thomas; Hansen, Tom Johnny; Remø, Sofie C.; Olsen, Rolf Erik; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2022)Interspecific hybridisation may improve the farm performance of sterile triploid salmonids via heterosis (i.e. hybrid vigour). We assessed growth over the final 293 days in seawater, and harvest quality, in diploid and ... -
Triploidy effects growth, life history strategies, and bone health in Arctic char (Salvelinus alpinus), but does not impact cataract incidence
Fraser, Thomas; Hansen, Tom Johnny; Remø, Sofie C.; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2021)Skeletal deformities and ocular cataracts have limited the farm performance of sterile triploid salmonids, but have not been assessed in Arctic char (Salvelinus alpinus). We repeatedly radiographed mixed-sex diploid and ... -
Triploidy leads to a mismatch of smoltification biomarkers in the gill and differences in the optimal salinity for post-smolt growth in Atlantic salmon
de Fonseka, Raneesha; Fjelldal, Per Gunnar; Sambraus, Florian; Nilsen, Tom Ole; Remø, Sofie C.; Stien, Lars Helge; Reinardy, Helena; Madaro, Angelico; Hansen, Tom Johnny; Fraser, Thomas (Peer reviewed; Journal article, 2021)Sterile triploid Atlantic salmon (Salmo salar) show inconsistent seawater grow-out, but the reason why remains unclear. The purpose of this study was to determine the salinity optima of triploid post-smolts. Diploids and ... -
Vertebral deformities in interspecific diploid and triploid salmonid hybrids
Fraser, Thomas; Hansen, Tom Johnny; Sambraus, Florian; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2020) -
Vgll3 and the Hippo pathway are regulated in Sertoli cells upon entry and during puberty in Atlantic salmon testis
Kjærner-Semb, Erik Nordtorp; Ayllon, Fernando; Kleppe, Lene; Sørhus, Elin; Skaftnesmo, Kai Ove; Furmanek, Tomasz; Segafredo, Frida Thyri; Thorsen, Anders; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Taranger, Geir Lasse; Andersson, Eva; Schulz, Rüdiger W.; Wargelius, Anna; Edvardsen, Rolf (Journal article; Peer reviewed, 2018)Vgll3 is linked to age at maturity in Atlantic salmon (Salmo salar). However, the molecular mechanisms involving Vgll3 in controlling timing of puberty as well as relevant tissue and cell types are currently unknown. Vgll3 ... -
Water temperature and dietary histidine affect cataract formation in Atlantic salmon (Salmo salar L.) diploid and triploid yearling smolt
Sambraus, Florian; Fjelldal, Per Gunnar; Remø, Sofie C.; Hevrøy, Ernst Morten; Nilsen, Tom Ole; Thorsen, Anders; Hansen, Tom Johnny; Waagbø, Rune (Peer reviewed; Journal article, 2017) -
Wild Atlantic salmon enter aquaculture sea-cages: A case study
Fjelldal, Per Gunnar; Bui, Samantha; Hansen, Tom Johnny; Oppedal, Frode; Bakke, Gunnar O; Hellenbrecht, Lea Marie; Knutar, Sofie; Madhun, Abdullah Sami (Peer reviewed; Journal article, 2021)There are more than 3,000 Atlantic salmon aquaculture sea-cages distributed along the coastline of Norway. Many of these sea-cages are located along the migration routes of wild Atlantic salmon (Salmo salar) postsmolts. ...