Torstein Kristensen

Nord University | HIBO · Faculty of Biosciences and Aquaculture

The timing of smolt migration is a key phenological trait with profound implications for individual survival during both river descent and the subsequent sea sojourn of anadromous fish. We studied relationships between the time of smolt migration, water temperature and light intensity for Atlantic salmon (Salmo salar) and sea trout (Salmo trutta)....

Runoff of metals represents one of the major environmental challenges related to historic and ongoing mining activity. In this study, transcriptomics (direct RNA sequencing [RNA-seq] and reverse-transcription quantitative polymerase chain reaction [RT-qPCR]) was used to predict toxicity of metal-rich acid mine drainage (AMD) water collected in the...

Mine tailings, containing metals and production chemicals such as flotation chemicals and flocculants, may pose an environmental threat to aquatic organisms living in downstream ecosystems. The aim of this work was to study to which degree Lilaflot D817M, a flotation chemical extensively used by the mining industry, represents a hazard for migratin...

Amoebic gill disease (AGD) and sea lice are two of the most significant disease issues facing the Norwegian Atlantic salmon aquaculture industry. Although both diseases respond to various extents, to freshwater treatment, the chemistry, interactions and efficacy of treatment can be variable. These variations can have significant impacts upon the su...

Facultative anadromous salmonids may alter migratory behavior to mitigate against detrimental infections of aquaculture‐derived salmon lice (Lepeophtheirus salmonis); however, this likely incurs negative growth and fitness consequences. This flexibility in migratory behavior also creates analytical challenges in estimating lice infestation levels a...

Juvenile Atlantic salmon (Salmo salar), known as post-smolt as they enter the sea, undergo an arduous migration from their natal rivers to their feeding grounds in the North Atlantic Ocean. It has become increasingly important to understand how post-smolts use the fjord environment as they migrate in order to properly assess the potential threats p...

Juvenile Atlantic salmon (Salmo salar), known as post-smolt as they enter the sea, undergo an arduous migration from their natal rivers to their feeding grounds in the North Atlantic Ocean. Here, we present data on the depth use of migrating wild Atlantic salmon post-smolts. Using acoustic telemetry, tagged fish from four rivers in two fjords in we...

Background Anadromy comprises a successful life-cycle adaptation for salmonids, with marine migration providing improved feeding opportunities and thus improved growth. These rewards are balanced against costs from increased energy expenditure and mortality risk. Anthropogenic-induced environmental changes that reduce benefits and/or increase costs...

Acid mine drainage (AMD) is widely acknowledged as a substantial threat to the biodiversity of aquatic ecosystems. The present study aimed to study the toxicological effects of Cu-rich AMD from the Sulitjelma mine in zebrafish larvae. The AMD from this mine was found to contain elevated levels of dissolved metals including Mg (46.7 mg/L), Al (20.2...

The purpose of the current project was to describe the potential for the production of juvenile fish upstream of Sjurhaugfoss and to come up with proposals for discussion of measures that will be able to realize this. When Lærdalselva was regulated with the Borgund and Stuvane power plants, negative effects on anadromous stocks were to be compensat...

As a part of a multi-year project, a study of migration timing and marine migration behaviour of wild Atlantic salmon (Salmo salar) smolts/post-smolts was conducted using acoustic telemetry in the rivers Eio, Granvin, and Os and the adjacent Hardanger and Bjørnafjord fjord system, Western Norway. In all three of the studied populations, migration b...

Interactions of microplastics and persistent organic pollutants (POPs) associated with Atlantic salmon farming were studied to assess the potential role of microplastics in relation to the environmental impact of aquaculture. HDPE, PP, PET and PVC microplastics placed for 3 months near fish farms sorbed POPs from aquafeeds. PET and PVC sorbed signi...

Lumpfish are utilized to combat ectoparasitic epidemics in salmon farming. Research gaps on both cleaning behavior and client preferences in a natural environment, emphasizes the need to investigate the physiological impacts on lumpfish during cohabitation with piscivorous Atlantic salmon. Lumpfish (39.9 g, S.D ± 8.98) were arranged in duplicate ta...

As a part of a multi-year project, a study of migration timing and marine migration behaviour of wild Atlantic salmon (Salmo salar) smolts/post-smolts was conducted using acoustic telemetry in the rivers Eio, Granvin, and Os and the adjacent Hardanger and Bjørnafjord fjord system, Western Norway.

In this study we investigated potential impacts of Cu exposure at low, environmentally relevant, concentrations on early live stages of Atlantic cod (Gadus morhua). Cod embryos and larvae were exposed to 0.5 µg/L (low), 2 µg/L (medium), and 6 µg/L (high) Cu from 4 to 17 days post fertilisation (dpf). Hatching success, mortality, oxygen consumption,...

Biological, environmental, economic and ethical issues become increasingly pertinent as the scale of the aquaculture industry expands. This study used acoustic telemetry data and wavelet analysis to investigate behavioural patterns of Atlantic salmon when exposed to artificial underwater lights in fully stocked production cages located on the Norwe...

Mining and processing of minerals produce large quantities of tailings as waste. Some countries, including Norway, allow disposal of mine tailings in the sea. In this study we investigated the impacts of tailings from a calcium carbonate (CaCO3) processing plant on early live stages of haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morh...

First interaction with carnivorous clients induces stress responses even in the boldest of cleaner fishes observed in nature. This is relevant for the expanding use of lumpfish in aquaculture, where stress could impede the species ability to interact with Atlantic salmon. The study investigated how naive lumpfish (34.3 g, S.D. ± 6.48) responded to...

Aim Accurate predictions about transition timing of salmon smolts between freshwater and marine environments are key to effective management. We aimed to use available data on Atlantic salmon smolt migration to predict the emigration timing in rivers throughout Norway. Location In this study, we used outmigration timing data of Atlantic salmon (Sa...

Marine tailing disposal (MTD) is sometimes practiced as an alternative to traditional mine tailing deposition on land. Environmental challenges connected to MTD include spreading of fine particulate matter in the water column and the potential release of metals and processing chemicals. This study investigated if tailing exposure affects the marine...

The timing of the smolt migration of Atlantic salmon ( Salmo salar ) is a phenological trait increasingly important to the fitness of this species. Understanding when and how smolts migrate to the sea is crucial to understanding how salmon populations will be affected by both climate change and the elevated salmon lice concentrations produced by sa...

Background Behaviour of potential host fish during chemical treatment against the ectoparasite Gyrodactylus salaris is a vital factor in designing treatment strategies, evaluating risk factors and establishing insights into previously failed treatments. The effectiveness of any chemical treatment may be compromised if fish either are forced to, or...

Heat waves are threatening fish around the world, leading sometimes to mass mortality events. One crucial function of fish failing in high temperatures is oxygen delivery capacity, i.e. cardiovascular function. For anadromous salmonids, increased temperature could be especially detrimental during upstream migration since they need efficiently worki...

A study of migration timing and marine migration behaviour of wild Atlantic salmon (Salmo salar) smolts/post-smolts was conducted using acoustic telemetry in the rivers Eio, Granvinselva and Oselva and the adjacent Hardanger and Bjørnafjord fjord system, Western Norway. Both Granvinselva and Eio-Bjoreio consist of two stretches of river separated b...

The proportion of angled Atlantic salmon Salmo salar L. being caught and released has increased. If individuals are repeatedly captured, this may have fish welfare consequences. Of 995 Atlantic salmon tagged during catch and release in eight Norwegian rivers, 10% were captured twice, while 3% were captured three times within the same fishing season...

Lumpfish (Cyclopterus lumpus) are valuable to the aquaculture industry due to the species ability to clean farmed Atlantic salmon (Salmo salar) for ectoparasites. Cleaning behaviour varies among individuals and the interspecific evolutionary relationship, in comparison with more established understanding of obligate “full time” cleaners and their c...

Screening has revealed that modern-day feeds used in Atlantic salmon aquaculture might contain trace amounts of agricultural pesticides. To reach slaughter size, salmon are produced in open net pens in the sea. Uneaten feed pellets and undigested feces deposited beneath the net pens represent a source of contamination for marine organisms. To exami...

A study of migration timing and marine migration behaviour of Atlantic salmon (Salmo salar) smolts/post-smolts was conducted using acoustic telemetry in the rivers Stryneelva and Eidselva and the adjacent fjord system (Nordfjord), Western Norway. During April 2018, 32 and 65 salmon smolt individuals from Stryneelva and Eidselva were captured (elect...

To investigate how lumpfish interact in Atlantic salmon aquaculture, physiological stress responses and changes in behaviour were analysed in experienced and naive lumpfish. Experienced lumpfish (30.2 ± 7.93 g, mean ± SD) coexisted with a commercial scale production unit of Atlantic salmon (1258.5 ± 152.12 g) for 30 to 60 days, while naive lumpfish...

A study of migration timing and marine migration behaviour of Atlantic salmon (Salmo salar) smolts/post-smolts was conducted using acoustic telemetry in the rivers Eio, Granvinselva and Oselva and the adjacent Hardanger and Bjørnafjord fjord system, Western Norway. During April 2018, 74, 86 and 93 salmon pre-smolt individuals from Eio, Granvinselva...

In this study the performance of the Internet of Fish (IoF) concept, a real-time acoustic positioning and fish monitoring system, was assessed in a commercial marine fish farm in Norway. Central to the IoF concept is the Synchronisation and LoRa Interface Module (SLIM), which is a battery operated surface unit that provides distributed time synchro...

Acid deposition has led to acidification and loss of fish populations in thousands of lakes and streams in Norway. Since the peak in the late 1970s, acid deposition has been greatly reduced and acidified surface waters have shown chemical recovery. Biological recovery, in particular fish populations, however, has lagged behind. Long-term monitoring...

A study of migration timing and marine migration behaviour of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) smolts/post-smolts was conducted using acoustic telemetry in the Stryneelvaeelva and the adjacent Nordfjord fjord system, Western Norway. Juvenile fish abundance and macroinvertebrate communities were also sampled in the rivers...

Det overordna føremålet med prosjektet var å auke verdiskapinga av sportsfisket i elva gjennom meir kunnskapsbasert forvaltning. Verdiskapingspotensialet ligg i auka betalingsvilje for fiske i Lærdalselvi. Auka betalingsvilje for fiske og berekraftig lokal forvalting heng tett saman, då ein må redusere uttaket for å sikre gytebestandane og samstund...

The River Vosso population of Atlantic salmon (Salmo salar) was strongly reduced over the course of a few years during late 1980s, and has not recovered since, despite substantial mitigation efforts. The ultimate reason(s) for the population decline remains enigmatic, as are the causes for lack of recovery. After decades of poor returning numbers o...

Rapporten omhandler vandringsstudier av sjøaure i Drivavassdraget og utenforliggende fjord-områder i perioden 2009-2011. Høsten 2009 og våren 2010 ble umoden og voksen sjøaure i Driva fanget ved hjelp av sportsfiskeutstyr og kastenot. Sjøaurene ble utstyrt med nyutviklete sendere utstyrt med dybdesensorer. I Sunndalsfjorden og Tingvollfjorden ble d...

The River Vosso population of Atlantic salmon (Salmo salar) was strongly reduced over the course of a few years during late 1980s, and has not recovered since despite strong mitigating efforts. The ultimate reasons(s) for the population decline is currently unclear, as are the causes for lack of recovery. After decades of poor numbers of returning...

Kunnskap om tidspunkt for utvandring og vandringsmønster utover i fjordsystemet til smolt i det enkelte vassdrag er viktig for å kunne oppnå større presisjon for både avlusingstiltak og overvaking. Vurderingar knytt til effektar på den konkrete bestanden kan då gjerast på eit betre grunnlag enn kva som er tilfelle i dag. I 2014 vandra 90 % av akust...

METHODS Brown trout stocks were assessed by benthic gill-nets, and the catches is expressed as numbers of individuals 100 m -2 of net area [CPUE]. We used both total numbers [CPUE-T] and those of age 2+ fish [CPUE-2], which represent the recruitment strength. We correlated CPUE both with ANC based on water chemistry from the same autumn as the test...

Tidligere modelleringsarbeid på sannsynlighet for regional sekundær spredning av Gyrodactylus salaris har pekt på tilførsel av ferskvann (dvs vannføring i elv) og salinitet i fjordområdene som kritiske variabler som påvirker smittesannsynlighet. Dette kommer i tillegg til at antall smolt som vandrer ut også påvirker spredningssannsynligheten. Disse...

Kartlegging av utvandringstidspunkt og marin åtferd til smolt av laks vart undersøkt ved hjelp av akustisk telemetri. Det vart i april- mai 2013 akustisk merka totalt 120 vill og 119 klekkerismolt av laks i Lærdalselvi. Smolt vart sett ut oppstrøms og nedstrøms kraftverket ved Stuvane i Lærdalselvi på tre tidspunkt i april- mail før smoltutvandring...

I samband med forskings- og utgreiingsarbeid knytt til behandlingar mot Gyrodactylus salaris i Lærdalselvi i 2008-2010 er det framskaffa interessante data på sjøaurestamma sin generelle biologi i Lærdalselvi. Studiar av vandringsåtferd i elv og fjord er gjennomførde ved bruk av akustiske telemetrimerke og automatiske lyttestasjonar/hydrofonbøyer. D...

The duration of hypoosmoregulatory capacity in downstream migrating Atlantic salmon Salmo salar L smolts previously stocked as startfed young-of-the year (YOY) parr was tested in the river Dalåa from mid-May to late June 1999. Hypo-osmoregulatory capacity, measured as plasma osmolality and chloride, were assessed after seawater challenge tests (168...

Atlantic salmon Salmo salar smolts were exposed to one of the four different aerobic exercise regimens for 10 weeks followed by a 1 week final smoltification period in fresh water and a subsequent eight-day seawater transfer period. Samples of gill and intestinal tissue were taken at each time point and gene expression was used to assess the effect...

Monitoring programmes have demonstrated seasonal and short term variation of inlet water quality in Chilean salmon hatcheries. Potentially toxic levels of copper (Cu) and aluminium (Al) in many cases may explain observed increased mortalities during the early life-stages of Atlantic salmon. Therefore, there is a need for efficient water treatments...

This study presents an improved duplex quantitative polymerase chain reaction (qPCR) method using the master sex-determining gene sdY as a marker for simultaneous genetic sex identification of salmonids of the Salmo genus and paternity elucidation for Salmo salar × Salmo trutta hybrids. This method will provide a new, simple and economical molecula...

Migration timing, speed, survival and effects of environmental parameters on migration, between wild and hatchery produced Atlantic salmon, Salmo salar L., smolts in the River Lærdalselva were studied. Hatchery-reared (n = 40) and wild pre-smolts (n = 40) were tagged with acoustic tags, and an array of receivers along the migration route was deploy...

The objective of the study was to determine whether exposure to fine-fraction discharge from iron ore processing at Rana Gruber AS in relevant doses may cause toxic effects in Atlantic salmon (Salmo salar) smolt. A 96h exposure study with 4 treatments (n=20) and a control group was conducted on smolts of local strain (River Røssåga) produced as 1 y...

Cardiac muscle is a principal target organ for exercise-induced acclimation mechanisms in fish and mammals, given that sustained aerobic exercise training improves cardiac output. Yet, the molecular mechanisms underlying such cardiac acclimation have been scarcely investigated in teleosts. Consequently, we studied mechanisms related to cardiac grow...

Genes and primer sequences used for the qPCR analyzes. (DOC)

High levels of hybridization between Atlantic salmon Salmo salar and brown trout Salmo trutta have been reported in the River Driva. This study presents the underlying mechanisms of development of seawater (SW) tolerance and marine migration pattern for S. salar×S. trutta hybrids. Migrating S. salar×S. trutta hybrid smolts caught in the River Driva...

This report examines the migration patterns and anadromous brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) in the Repparfjord River as a further investigation of earlier reported work (NIVA-rapport 6167-2011). Most of the study focuses on migration timing and residence time at sea. Due to low number of detected fish there was no 21...

One of the major challenges for understanding the ecological impact of escaped farmed Atlantic salmon (Salmo salar L.) is predicting their dispersal patterns after an escape event. Here, we quantify the behaviour of escaped farmed salmon using a simulated-escape experiment within a Norwegian fjord system. Thirty-seven individuals were tagged with a...

Acidification is acknowledged as a cause for extinction or catch reductions in numerous rivers supporting Atlantic salmon (Salmo salar L.) populations in Norway. In freshwater, labile (cationic/inorganic) forms of Al (LAl) accumulate onto and in fish gills, where high concentrations can result in mortality due to respiratory and ionoregulatory dysf...

A data set from commercial Atlantic salmon (Salmo salar L.) producers on production intensity and production strategies in smolt tanks (N = 63–94) was obtained during 1999–2006. The effects of production intensity on subsequent fish mortality and growth during the early sea phase (90 days) were examined by principal component analysis and subsequen...

Hydropower regulation of a water course normally implies that the lakes are dam-med to store water for el-production in periods with low runoff. The watercourse will then get a larger volume, which re-sults in increased retention of phos pho-rus, and consequently oligotrophication of the lake. Almost without exception, this oligotrophication result...

The main focus of the study was to document the timing of downstream migration and migration speed of Atlantic salmon smolts, as well as marine behaviour of sea trout and arctic char. All these anadromous species spend part of their lifecycle in the estuary/fjord system. Behavioural data is therefore a vital input in risk assessments towards these...

During recent years, R&D efforts linked to the ongoing Gyrodactylus salaris eradication projects in River Lærdalselva have generated interesting data on the biology of anadromous brown trout (Salmo trutta). Telemetry studies on the behaviour in the river and fjord have been conducted, and scale samples as well as genetic samples have been collected...

Actively migrating wild Atlantic salmon (Salmo salar) smolts from 4 rivers with different environmental conditions were sampled for the determination of circulating atrial natriuretic peptide (ANP) levels and heart morphological measurements. A comparison with smolts from aquaculture production with different water velocities was performed. ANP lev...

Atlantic salmon smolts were exposed to three doses of the fungicide azoxystrobin for 4 days, and physiological blood parameters and transcriptional effects in liver and muscle were evaluated in search for potential negative effects. Azoxystrobin exposure mediated up-regulation of catalase, MAPK1 and IGFBP1 in liver tissue. Catalase, transferrin, IG...