Thrond Haugen

Norwegian University of Life Sciences (NMBU) · Department of Ecology and Natural Resource Management (INA)

Background Acoustic telemetry is widely used as a method for high resolution monitoring of aquatic animal movement to investigate relationships between individual animals and their environment. In shallow freshwater ecosystem, aquatic macrophytes are common and their presence increases habitat complexity and baffles sound propagation. These propert...

By hindering migration and inducing direct turbine mortality during downstream migration, hydropower is regarded as one of the most serious threats to anadromous salmonids. Yet, little attention has been paid to long-term turbine-induced selection mechanisms effecting fish populations. This work evaluates turbine and post-turbine survival of PIT-ta...

Total dissolved gas supersaturation from dams and power stations is a chronic freshwater pollutant that is toxic to animals with aquatic respiration. Laboratory ecotoxicology experiments have revealed some capacity for captive fishes to saturoregulate by moving deeper, but field ecotoxicology research is largely lacking. We instrumented 94 brown tr...

Renewable energy projects such as hydropower facilities contribute towards meeting the world`s growing energy demands and urgent need for mitigating climate change. However, such infrastructure has the potential to substantially alter the environment which, in turn, can induce new challenges related to for instance fish migration conditions. As a c...

Climate-induced plasticity in functional traits has received recent attention due to the immense importance phenotypic variation plays in population level responses. Here, we explore the effect of different climate-change scenarios on lentic populations of a freshwater ectotherm, the brown trout (Salmo trutta L.), through climate effects on functio...

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 late March and early April of 2020, 62, 56, and...

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...

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...

Anthropogenic activities affect fish populations worldwide. River dams have profound impacts on ecosystems by changing habitats and hindering migration. In an effort to counteract such effects, a range of mitigation measures have been installed at hydroelectric power plants. However, not all individuals in a population use these measures, potential...

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...

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...

Norway has the highest participation rate in marine recreational fisheries (MRF) in Europe, and is popular among marine tourist anglers. Fishing licences are not required for marine recreational anglers, and the complex and long coastline makes on-site surveys a challenge. A novel approach for spatial sampling was developed and tested in on-site su...

The cover image is based on the Research Article Common mechanisms for guidance efficiency of descending Atlantic salmon smolts in small and large hydroelectric power plants, by Tormod Haraldstad et al., https://doi.org/10.1002/rra.3360. Photo credit: Tormod Haraldstad.

Dams and turbines associated with hydroelectric power plants (HEP) disrupt connectivity by affecting fish movement and survival. There has been an increasing focus on measures to facilitate downstream migration at HEPs. The fish guidance efficacy (FGE) of downstream mitigation measures largely remains suboptimal and calls for development of knowled...

Repeat spawners of anadromous salmonids may contribute significantly to population resilience by providing multiple cohorts to both sea- and freshwater life stages. In this study, winter survival of sea trout (Salmo trutta) post spawners (kelts) was 89 %. Sea survival increased linearly with female length with return probability between 30 and 50 %...

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...

Polar regions are characterized by acute seasonal changes in the environment, with organisms inhabiting these regions lacking diel photoperiodic information for parts of the year. We present, to our knowledge, the first high-resolution analysis of diel and seasonal activity of free-living fishes in polar waters (74°N), subject to extreme variation...

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)....

This study focuses on plerocercoids of the cestode Diphyllobothrium ditremum in brown trout Salmo trutta from the subalpine lake Øvre Heimdalsvatn in south–central Norway. Salmo trutta was the only fish species in this lake until European minnow Phoxinus phoxinus was registered in 1969. The P. phoxinus population increased substantially in the foll...

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...

Abstract To study effects from natural selection acting on brown trout in a natural stream habitat compared with a hatchery environment, 3,781 single nucleotide polymorphism (SNP) markers were analyzed in three closely related groups of brown trout (Salmo trutta L.). Autumn (W/0+, n = 48) and consecutive spring (W/1+, n = 47) samples of brown trout...

Behaviour of early life stages of the salmonid European grayling Thymallus thymallus was investigated by assessing the timing of larval downstream movement from spawning areas, the depth at which lar-vae moved and the distribution of juvenile fish during summer in two large connected river systems in Norway. Trapping of larvae moving downstream and...

Climate-change scenarios predict increasing temperatures and more precipitation at high latitudes. Ectothermic species are highly affected by these environmental variables and due to few dispersal opportunities many populations will need to adapt to these environmental changes. Understanding if, where, and how such adaptation processes occur is imp...

The original version of this article unfortunately contained a mistake. Leif Asbjørn Vøllestad's surname was incorrectly presented as Vøllestada. The original article was corrected.

The precision of growth estimates based on fish scales often remains uncertain because of withinindividual variation in scale size and scale patterns, and also due to measurement errors. Based on scale readings of Atlantic salmon, we show that errors decreased with number of times and number of scales read per fish. The annual number of scale circu...

Within-river movements and distribution of wild and escaped farmed Atlantic salmon before and during spawning were compared. Seventy-four wild and 43 escaped farmed Atlantic salmon were captured in the sea, tagged with radio transmitters and released. Based on examination of farmed and wild Atlantic salmon most, if not all, fish entering the River...

Microsatellites (10 MSs) and single nucleotide polymorphism (3871 SNPs) were analysed in three closely related, single-cohort groups of brown trout, Salmo trutta L. Autumn (W/0+) and subsequent year (W/1+) samples of brown trout of the same stream were retrieved using electric fishing, and one sample of artificially reared brown trout (H/1+), bred...

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...

Low density in natural populations of salmonids has predominantly been managed by stocking of non-native conspecifics. Due partly to domestication, introduced non-native fish may be maladapted under natural conditions. Interbreeding between introduced and wild individuals may therefore impair local adaptation and potentially population viability. B...

Antall pre-smolt oppstrøms Rygene, 3546 (3083-4214), er lavere en hva en kunne forvente utfra antall oppvandrende gytefisk og egnet gyte- og oppvekstareal i elva. I tillegg estimeres et betydelig tap av smolt under nedvandring. Sistnevnte skyldes antagelig to forhold; predasjon fra gjedde og vandring gjennom kraftverksturbinen på Rygene. Det ble i...

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...

Knowledge of the horizontal and vertical distribution and habitat use of fish in lakes provides insights into the ecology, evolution and conservation of a species. Using high-resolution, high-frequency sampling, we provide an account of the distribution and movements of adult European grayling, Thymallus thymallus, in a recently colonised subarctic...

The report summarizes work to develop methods for using data on the fish stocks as an ecological quality element for classification of water bodies (lakes and rivers) under EU’s Water Framework Directive in Norway. The aim of the work in the “Advisory Committee on Fish in the Water Directive” established by the Directorate for Nature Management (pr...

Equilibrium passive sampling through in vivo implantation can help circumvent complex extractions of biological tissues, provide more accurate information on chemical contaminant burden based on the fugacity of a chemical in an organisms rather than conventional normalization to lipid content, and improve the assessment of contaminant bioaccumulati...

Fishing can have profound impacts on the ecology and evolution of marine populations. Understanding population level changes ultimately depends on knowledge about individual survival and how it varies in time and space. We used acoustic tags and a network of receivers to monitor individual behaviour and fate of European lobster exposed to a commerc...

1. Growth is a key life-history trait linked to population regulation in fishes and may be influenced by biotic and abiotic factors such as density and temperature. Exploring how growth performance is altered by such factors in the wild will aid our understanding of how climate change might influence fish populations. 2. We explore the interactions...

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...

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...

Summary table for deme-wise linear regressions of ln(yolk sac area) on degree days in the three treatment temperatures. In Table A3 the intercept, slope (with SE), adjusted r2 and N are given. The results are also visualised in Figure A3.

Parameter estimates (± se) for the factors included in linear mixes models (see equation 1 in main text).

Summary table for deme-wise linear regressions of ln(length) on degree days in the three treatment temperatures. In Table A2 the intercept, slope (with SE), adjusted r2 and N are given. The results are also visualised in Figure A2.

Following colonization of new habitats and subsequent selection, adaptation to environmental conditions might be expected to be rapid. In a mountain lake in Norway, Lesjaskogsvatnet, more than 20 distinct spawning demes of grayling have been established since the lake was colonized, some 20-25 generations ago. The demes spawn in tributaries consist...

Lesjaskogsvatnet is a Norwegian lake that experienced a founder event in the late 19th century that temporarily allowed an influx of European grayling (Thymallus thymallus), a typically fluvial palearctic salmonid. While adult grayling reside in the lake for most of the year, they require stream habitat for spawning. Over twenty streams with potent...

There is an increasing body of documentation demonstrating fisheries-induced adaptational change (FAC) in important fish life-history traits. An often documented adaptation outcome, especially in fisheries targeting the larger individuals, is altered age- and size at maturation pattern so as to maturing earlier and/or at smaller sizes than before h...

Divergent selection pressures, induced by variations in environmental conditions and resource availability, can be expected to favor different phenotypic expressions. Hence, different populations often show local adaptations that can be attributed to their respective environments. However, population differentiation may also be due to genotype-envi...

In this paper, we use dynamic factor and intervention analysis to identify and quantify the effect of human encroachments on anadromous salmonid catches in 22 Norwegian rivers over a 128-year period. In particular, we address effects of hydropower development, gravel removal, and stock enhancement (fish ladder construction and stocking). The method...

Gene flow has the potential to both constrain and facilitate adaptation to local environmental conditions. The early stages of population divergence can be unstable because of fluctuating levels of gene flow. Investigating temporal variation in gene flow during the initial stages of population divergence can therefore provide insights to the role o...

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...

Qst vs Fst comparisons between pairs of the four demes included in the study (Figure A3). The plots comprise sensitivity plots of QST-values under various g and h2 settings. Left panels show simulations for muscle fiber area, middle panels for notochord length and right panels for the skeletal trait hypurals (as an example of skeletal trait). Horiz...

Parameter estimates and model fit statistics for the most supported models fitted to estimate group effects for 11 traits involved in the study (Table A1).

Characteristics of microsatellite loci applied in the study. (Table A2).

Analysis of environmental differences between streams with particular attention to water temperature and consequences for timing of spawning and development temperatures. A detailed description of a dynamic factor analysis (DFA) that utilize time-series data on water temperatures covering four years of data. The analysis groups the streams into col...

Evaluating the limits of adaptation to temperature is important given the IPCC-predicted rise in global temperatures. The rate and scope of evolutionary adaptation can be limited by low genetic diversity, gene flow, and costs associated with adaptive change. Freshwater organisms are physically confined to lakes and rivers, and must therefore deal d...

The health hazard of mercury (Hg) compounds is internationally recognized, and the main pathways for methylmercury (MeHg) intake in humans are through consumption of food, especially fish. Given the large releases of Hg to the environment in China, combined with the fast development of hydropower, this issue deserves attention. Provided similar mob...

Chronic social stress diverts energy away from growth, reproduction and immunity, and is thus a potential driver of population dynamics. However, the effects of social stress on demographic density dependence remain largely overlooked in ecological theory. Here we combine behavioural experiments, physiology and population modelling to show in a top...

Sibling-size variation (SSV), estimated as the coefficient of variation of egg size, was investigated for 13 populations of brown trout Salmo trutta. SSV was negatively correlated with mean egg size both at the population and individual levels. After correction for the effect of mean egg size, SSV was also negatively correlated with stream size. Th...

The development of isolation by distance (IBD) and isolation by time (IBT) was contrasted among demes of European grayling (Thymallus thymallus) that have diverged within the last 25 generations following colonization of a lake (Lesjaskogsvatnet). We find low but significant levels of genetic differentiation among spawning tributaries and a pattern...

Brown trout (Salmo trutta) are extensively harvested and its habitat highly influenced by human encroachments. Using a 40-year time series of mark–recapture data we estimate vital rates for a piscivorous trout population. This population spawns upstream of a waterfall, which historically acted as a migration barrier for smaller trout. In 1966, the...