Browsing Brage IMR by Author "Hvas, Malthe"
Now showing items 1-20 of 25
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Assessing swimming capacity and schooling behaviour in farmed Atlantic salmon Salmo salar with experimental push-cages
Hvas, Malthe; Folkedal, Ole; Solstorm, David; Vågseth, Tone; Fosse, Jan Olav; Gansel, Lars Christian; Oppedal, Frode (Peer reviewed; Journal article, 2017) -
Critical swimming speed in groups of Atlantic salmon Salmo salar
Remen, Mette; Solstorm, Frida; Bui, Samantha; Pascal, Klebert; Vågseth, Tone; Solstorm, David; Hvas, Malthe; Oppedal, Frode (Peer reviewed; Journal article, 2016) -
The effect of fasting period on swimming performance, blood parameters and stress recovery in Atlantic salmon post smolts
Hvas, Malthe; Stien, Lars Helge; Oppedal, Frode (Peer reviewed; Journal article, 2021)In this study, Atlantic salmon post smolts (~250 g, ~29 cm) were fasted for four weeks at 12 °C in full strength seawater. During this period, the critical swimming speed (Ucrit) was measured after 1, 2 and 4 weeks of ... -
Fasting and its implications for fish welfare in Atlantic salmon aquaculture
Hvas, Malthe; Kolarevic, Jelena; Noble, Christopher; Oppedal, Frode; Stien, Lars Helge (Peer reviewed; Journal article, 2024)Periods of fasting occur for a multitude of reasons in Atlantic salmon aquaculture. Feed withdrawal is widely used prior to transport, parasite treatments, preslaughter and for depuration purposes in recirculating aquaculture ... -
Fish welfare based classification method of ocean current speeds at aquaculture sites
Jónsdóttir, Kristbjörg Edda; Hvas, Malthe; Alfredsen, Jo Arve; Føre, Martin; Alver, Morten; Bjelland, Hans Vanhauwaert; Oppedal, Frode (Journal article; Peer reviewed, 2019)A major trend in marine aquaculture is to move production to more exposed sites with occasionally rough ocean current events. However, it is unclear whether fish will thrive in these extreme environments, since thorough ... -
Fish welfare in offshore salmon aquaculture
Hvas, Malthe; Folkedal, Ole; Oppedal, Frode (Peer reviewed; Journal article, 2020)To accommodate further growth in the Atlantic salmon aquaculture industry, new production sites may well be established at more exposed locations along the coast or even offshore. Here, fish will encounter strong currents ... -
Full compensatory growth before harvest and no impact on fish welfare in Atlantic salmon after an 8-week fasting period
Hvas, Malthe; Nilsson, Jonatan; Vågseth, Tone; Nola, Velimir; Fjelldal, Per Gunnar; Hansen, Tom Johnny; Oppedal, Frode; Stien, Lars Helge; Folkedal, Ole (Peer reviewed; Journal article, 2021)Individually tagged Atlantic salmon postsmolts (≈1200 g, 46 cm) reared in triplicate indoor holding tanks were fasted for 8 weeks at 12 °C and subsequently refed for 5 weeks, whereafter they were transferred to triplicate ... -
Havbasert oppdrett – hvor mye vannstrøm tåler laks og rensefisk? - fiskevelferd og grenseverdier
Hvas, Malthe; Folkedal, Ole; Oppedal, Frode (Rapport fra havforskningen;2019 - 37, Research report, 2019)I fremtiden ønskes oppdrettsanlegg på mer eksponerte lokaliteter, gjerne langt til havs. Da kan fisken oppleve langt sterkere vannstrøm enn på tradisjonelle lokaliteter. Tåler laksen dette? Det er mange fordeler med ... -
Heart rate bio-loggers as welfare indicators in Atlantic salmon (Salmo salar) aquaculture
Hvas, Malthe; Folkedal, Ole; Oppedal, Frode (Peer reviewed; Journal article, 2020)In this study, 12 farmed Atlantic salmon (~1200 g) were tagged with commercially available heart rate (HR) bio-loggers and maintained in a controlled fish tank laboratory environment at 9 °C on a 12 h day/night cycle for ... -
Influence of experimental set-up and methodology for measurements of metabolic rates and critical swimming speed in Atlantic salmon Salmo salar
Hvas, Malthe; Oppedal, Frode (Journal article; Peer reviewed, 2019)In this study, swim‐tunnel respirometry was performed on Atlantic salmon Salmo salar post‐smolts in a 90 l respirometer on individuals and compared with groups or individuals of similar sizes tested in a 1905 l respirometer, ... -
Influence of photoperiod and protocol length on metabolic rate traits in ballan wrasse Labrus bergylta
Hvas, Malthe (Peer reviewed; Journal article, 2021)In this study, ballan wrasse Labrus bergylta were subjected to either a conventional 1-day or an extended 5-day respirometry protocol. Additionally, in the 5-day protocol the fish were subjected to a 12 h light–dark cycle ... -
Is it advantageous for Atlantic salmon to be triploid at lower temperatures?
Riseth, Erling; Fraser, Thomas; Sambraus, Florian; Stien, Lars Helge; Hvas, Malthe (Peer reviewed; Journal article, 2020)Marine organisms living at low temperatures tend to have larger genomes and larger cells which suggest that these traits can be beneficial in colder environments. In fish, triploidy (three complete sets of chromosomes) can ... -
The metabolic rate response to feed withdrawal in Atlantic salmon post-smolts
Hvas, Malthe; Stien, Lars Helge; Oppedal, Frode (Peer reviewed; Journal article, 2020)Feed withdrawal is a widespread practice in Atlantic salmon (Salmo salar) aquaculture to empty the gut prior to major farming operations, while certain pathogens and suboptimal environmental conditions in production cages ... -
Metabolic rates, swimming capabilities, thermal niche and stress response of the lumpfish, cyclopterus lumpus
Hvas, Malthe; Folkedal, Ole; Imsland, Albert; Oppedal, Frode (Peer reviewed; Journal article, 2018)Metabolic rates, swimming capabilities, thermal niche and stress response of the lumpfish, cyclopterus lumpus -
Novel tag-based method for measuring tailbeat frequency and variations in amplitude in fish
Warren-Myers, F.; Svendsen, Eirik; Føre, Martin; Folkedal, Ole; Oppedal, Frode; Hvas, Malthe (Peer reviewed; Journal article, 2023)The tailbeat frequency (TBF) together with tailbeat amplitude (TBA) of fish are tightly correlated with swimming speed. In addition, these parameters can be used as indicators of metabolic rate and general activity level, ... -
Oxygen Uptake and Osmotic Balance of Atlantic Salmon in Relation to Exercise and Salinity Acclimation
Hvas, Malthe; Nilsen, Tom Ole; Oppedal, Frode (Peer reviewed; Journal article, 2018)The fish gill is subject to an osmorespiratory compromise in physiologically demanding situations where conditions that favor gas exchange may compromise osmotic balance, especially when large gradients between the blood ... -
Physiological responses of farmed Atlantic salmon and two cohabitant species of cleaner fish to progressive hypoxia
Hvas, Malthe; Oppedal, Frode (Journal article; Peer reviewed, 2019)To mitigate salmon lice infestations in Atlantic salmon (Salmo salar) sea cages, deployment of cleaner fish have become a widespread strategy. However, species of cleaner fish may experience poor welfare in the highly ... -
Sentinels in Salmon Aquaculture: Heart Rates Across Seasons and During Crowding Events
Warren-Myers, Fletcher; Hvas, Malthe; Vågseth, Tone; Dempster, Tim; Oppedal, Frode (Peer reviewed; Journal article, 2021)Advances in tag technology now make it possible to monitor the behavior of small groups of individual fish as bioindicators of population wellbeing in commercial aquaculture settings. For example, tags may detect unusual ... -
Skeletal deformities in wild and farmed cleaner fish species used in Atlantic salmon Salmo salar aquaculture
Fjelldal, Per Gunnar; Madaro, Angelico; Hvas, Malthe; Stien, Lars Helge; Oppedal, Frode; Fraser, Thomas (Peer reviewed; Journal article, 2020)As a first attempt to assess bone health in cleaner fish production, wild and cultured ballan wrasse Labrus bergylta and lumpfish Cyclopterus lumpus were examined by radiology. In C. lumpus, wild fish (57%) had more vertebra ... -
Sustained swimming capacity of Atlantic salmon
Hvas, Malthe; Oppedal, Frode (Peer reviewed; Journal article, 2017)