English
norskBlar i forfatter "Bjørn, Pål Arne"
Viser treff 1-14 av 14
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Area protection may reduce salmon louse infection risk to wild salmonids
(Journal article; Tidsskriftartikkel; Peer reviewed, 2011-05-30)ABSTRACT: Salmon louse <i>Lepeophtheirus salmonis</i> Krøyer infection levels in both wild sea trout <i>Salmo trutta</i> L. and sentinel Atlantic salmon <i>Salmo salar</i> L. smolts were investigated inside and outside a temporary protected zone with limits on fish farming in the intensively farmed Romsdalsfjord system. Wild sea trout outside the protected zone had higher prevalence and significantly ... -
Behaviour and habitat use of first-time migrant Arctic charr: novel insights from a subarctic marine area
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-13)Anadromous Arctic charr Salvelinus alpinus is a cold-adapted salmonid that is vulnerable to climate warming and anthropogenic activities including salmon farming, hydropower regulation, and pollution, which poses a multiple-stressor scenario that influences or threatens populations. We studied the horizontal and vertical behaviour of Arctic charr tagged with acoustic transmitters (n = 45, mean ... -
Behavioural responses of wild anadromous Arctic char experimentally infested in situ with salmon lice
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-24)Salmon lice can impact the marine behaviour, growth, and survival of salmonids, but little is known about their effects on Arctic char. We present behavioural responses from the first dose-response experiment with wild anadromous Arctic char (n = 50) infested in situ with salmon lice (0.0–1.2 lice g<sup>−1</sup> fish) in an area with low natural infestations. Infested fish spent less time at sea ... -
Effects of salmon lice on sea trout
(Research report; Forskningsrapport, 2014) -
Impacts of salmon lice on mortality, marine migration distance and premature return in sea trout
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-06)Brown trout <i>Salmo trutta</i> (L.) is a facultative anadromous species, where a portion of individuals in populations with access to the sea perform migrations to use the richer feeding resources. We investigated the effect of salmon lice <i>Lepeophtheirus salmonis</i> (Krøyer 1837) infestation on the survival and behaviour of wild trout post-smolts (average fork length = 180 mm) during their ... -
Kunnskapsgrunnlag for mulig påvirkning fra oppdrettstorsk og levendelagret torsk på villtorsk
(Research report; Forskningsrapport, 2021-05-26)Det er igjen økende interesse for torskeoppdrett, denne gang med en domestisert oppdrettstorsk som vil ha egenskaper som skiller seg fra vill torsk. Det er behov for et oppdatert kunnskapsgrunnlag om risiko for påvirkning på viltlevende torsk, spesielt genetiske og økologiske interaksjoner og lokalisering i forhold til gyte- og oppvekstområder. Denne rapporten som er bestilt av Fiskeridirektoratet ... -
Micro- and macro-habitat selection of Atlantic salmon, (Salmo salar), post-smolts in relation to marine environmental cues
(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 ... -
Movement diversity and partial sympatry of coastal and Northeast Arctic cod ecotypes at high latitudes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-24)Movement diversity within species represent an important but often neglected, component of biodiversity that affects ecological and genetic interactions, as well as the productivity of exploited systems. By combining individual tracking data from acoustic telemetry with novel genetic analyses, we describe the movement diversity of two Atlantic cod Gadus morhua ecotypes in two high-latitude fjord ... -
Movements of female lumpsucker Cyclopterus lumpus in a Norwegian fjord during the spawning period
(Research report; Forskningsrapport, 2007)Lumpsucker are distributed throughout the North Atlantic Ocean, and migrate considerable distances between offshore feeding areas and shallow inshore spawning areas. In July 2006, a study on the movements of female lumpsucker during the spawning period was carried out in Øksfjord, Northern Norway. Twenty fish (mean body mass 3.2 kg, range 1.5- 4.8 kg) were tagged with acoustic transmitters and ... -
Registreringer av lakselus på laks, sjøørret og sjørøye i 2004
(Research report; Forskningsrapport, 2005-06)Results from 2004 showed that the lice infection pressure varied between the different monitoring stations in time and space and that the overall pattern was moderate to high infection in all areas. This is in spite of the fact that the fish farmers have improved their implementation of delousing strategies in fish farms. The density of fish farms is high all along the coast. The total biomass may ... -
Sampling planktonic salmon lice in Norwegian fjords
(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
(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 ... -
Sea trout Salmo trutta in the subarctic: home-bound but large variation in migratory behaviour between and within populations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-28)Anadromous brown trout (sea trout), Salmo trutta, is currently in decline throughout its range, largely due to anthropogenic stressors in freshwater and marine habitats. Acoustic telmetry was utilized to study the marine migration of sea trout post-smolts from three populations in a relatively pristine subarctic fjord system. While at sea, the sea trout spent a substantial part of their time close ... -
Timing is everything: Survival of Atlantic salmon Salmo salar postsmolts during events of high salmon lice densities
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-07)<ol> <li>Atlantic salmon in aquaculture act as reservoir hosts and vectors of parasites like salmon lice and this parasite is shown to harm wild salmonid populations.</li> <li>In this study, <i>n</i> = 29,817 tagged Atlantic salmon were studied in four release trials. Half of the released fish were given prophylactic treatment against lice, the other half represented sham control fish. We used ...
