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  • 1.
    Ardren, W. R.
    et al.
    US Fish & Wildlife Service, USA.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Introduction to “conservation, ecology, and evolution of nonanadromous atlantic salmon”2021In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 78, no 6, p. iii-ViiArticle in journal (Refereed)
  • 2.
    Greenberg, Larry
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Norrgård, J. R.
    Gammelkroppa Lax AB.
    Gustafsson, P.
    County Administrative Board of Värmland.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Landlocked atlantic salmon in a large river-lake ecosystem: Managing an endemic, large-bodied population of high conservation value2021In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 78, no 6, p. 787-796Article in journal (Refereed)
    Abstract [en]

    Managing and conserving threatenedmigratory salmonid populations in large river-lake ecosystems is challenging not only because of the ecosystems’ large size, but also because there is often more than one anthropomorphic stressor. The River Klarälven - Lake Vänern ecosystem, situated in Norway and Sweden, is a large, highly modified ecosystem, home to a threatened, endemic, large-bodied population of landlocked Atlantic salmon (Salmo salar). With 11 dams, the salmon population has been maintained through extensive stocking and a truck and transport system for spawners. Here we review what we have learned about the salmon after 15 years of research, highlighting the major findings for each life stage. Our studies indicate that the salmon population is below carrying capacity, and we suggest measures to increase the number of spawners and downstream passage success. Habitat restoration to compensate for losses from former log-driving activities is expected to further increase carrying capacity. Re-establishing salmon in Klarälven’s upper reaches in Norway, while possible, is fraught with both ecological and legislative hurdles. Substantial long-termfunding is needed to foster co-management and ensure a sustainable fishery.

  • 3. Guenard, G.
    et al.
    Boisclair, Daniel
    Ugedal, Ola
    Forseth, Torbjörn
    Fleming, Ian A.
    Jonsson, Bror
    The bioenergetics ofdensity-dependent growth in Arctic char (Salvelinus alpinus L.)2012In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 69, p. 1651-1662Article in journal (Refereed)
  • 4.
    Guenard, Guillaume
    et al.
    Université de Montréal, Canada.
    Boisclair, Daniel
    Université de Montréal, Canada.
    Ugedal, Ola
    Norwegian Institute for Nature Research, Trondheim, Norway.
    Forseth, Torbjorn
    Norwegian Institute for Nature Research, Trondheim, Norway.
    Jonsson, Bror
    Norwegian Institute for Nature Research, Oslo, Norge.
    Comparison between activity estimates obtained using bioenergetic and behavioural analyses2008In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 65, no 8, p. 1705-1720Article in journal (Refereed)
    Abstract [en]

    Activity rate of Arctic char (Salvelinus alpinus) held in 90 m2 littoral enclosures were estimated using bioenergetic (with consumption estimated using stable caesium, 133Cs) and behavioural approaches (with fish movements quantified using video cameras). We found no statistically significant difference between values of activity rate obtained using the two approaches for three of the six experiments we performed. However, there was no relationship between estimates of activity rate obtained using the two approaches. Discrepancies may arise from the difficulty to meet assumptions regarding the temporal stability of the concentration of 133Cs in fish diet and of the assimilation coefficient of this tracer. When fish remain in an area where their behaviour can be well described (e.g., enclosure, habitat patches of littoral zones, coral reefs), the behavioural approach appears more robust to estimate activity rate because it depends most on a variable that is easiest to estimate (the number of movements performed). When these conditions are not met (low fish densities or major fish migrations), a reliable assessment of the concentration and assimilation of 133Cs in stomach contents appears critical to implement the bioenergetic approach based on this tracer.

  • 5.
    Guenard, Guillaume
    et al.
    De´partement de sciences biologiques, Universite´ de Montre´al,.
    Boisclair, Daniel
    De´partement de sciences biologiques, Universite´ de Montre´al,.
    Ugedal, Ola
    Norwegian Institute for Nature Research, Trondheim, Norway..
    Forseth, Torbjorn
    Norwegian Institute for Nature Research, Trondheim, Norway..
    Jonsson, Bror
    Norwegian Institute for Nature Research, Oslo, Norway..
    Fleming, Ian A.
    Ocean Sciences Centre, Memorial University of Newfoundland, Canada..
    Experimental assessment of the bioenergetic and behavioural differences between two morphologically distinct populations of Arctic char (Salvelinus alpinus)2010In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 67, p. 580-595Article in journal (Refereed)
    Abstract [en]

     

    A common environment experiment was conducted to assess the magnitude of the difference in growth, consumption,

    activity rate, and spatial and temporal patterns of habitat use between morphologically different populations of

    Arctic char (Salvelinus alpinus) originating from two Norwegian lakes. These two lakes contrasted sharply in terms of surface

    area, depth, elevation, length of the winter period, and fish community structure (presence–absence of brown trout,

    Salmo trutta). The experimental framework encompassed four littoral enclosures (average volume, 146 m3) stocked with

    char from either of the two populations with duplicated treatments. Char morphology was quantified with numerical image

    analysis, food consumption was estimated using caesium analysis (133Cs), and activity cost and patterns were determined

    using video cameras. Char populations were morphologically distinct and reacted differently in growth (1.9-fold difference

    between populations), food consumption (3-fold difference), and spatial activity patterns (20-fold difference) to the conditions prevailing in the enclosures. The results highlight that functional differences between morphologically distinct char

    may drive important differences in their bioenergetic and behavioural responses when exposed to similar environmental

    conditions. Such functional differences should be incorporated when developing habitat or trophic cascade models.

  • 6.
    Hagelin, Anna
    et al.
    Länsstyrelsen i Västra Götalands län.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Competition among juvenile brown trout, grayling, and landlocked Atlantic salmon in flumes: predicting effects of interspecific interactions on salmon reintroduction success2021In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 78, no 3, p. 332-338Article in journal (Refereed)
    Abstract [en]

    Worldwide declines in salmonid populations have generated major interest in conservation and restoration of wild populations and riverine habitats. Species reintroductions to previous habitats raise questions about their potential impact on these systems. In River Klaralven, landlocked Atlantic salmon (Salmo solar) have been extinct from upper reaches for over 50 years due to hydropower dams. Here we study competitive interactions among juvenile salmon, grayling (Thymallus thymalius), and brown trout (Salmo trutta) that occur in the upper reaches of the river. We examine foraging rates, aggression, and activity of juvenile fish in allopauy at three different densities and in sympatry with one or both potential competitors in laboratory flumes. Salmon captured prey less frequently in the presence of brown trout and grayling, whereas grayling and brown trout were unaffected by salmon, but affected each other. Grayling was the most aggressive and active species, whereas salmon the least. Consequently, reintroduction of salmon probably will have little impact on grayling and brown trout, whereas grayling and brown trout could affect the success of reintroducing salmon.

  • 7.
    Hagelin, Anna
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Museth, Jon
    Norsk institutt for naturforskning NINA, NOR.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Kraabol, Morten
    Multiconsult, NOR.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Upstream fishway performance by Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) spawners at complex hydropower dams – is prior experience a success criterion?2021In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 78, no 2, p. 124-134Article in journal (Refereed)
    Abstract [en]

    Passage of hydropower plants by upstream-migrating salmonid spawners is associated with increased mortality, delays, injuries and reduced migration success, and consequently the need for a more comprehensive understanding of fish behavior downstream of dams is widely recognized. Studies of passage typically involve tagging fish, and in many cases, the fish used in these studies are caught in the fishways, and hence have prior experience negotiating them. In this study, we studied fishway passage of tagged landlocked Atlantic salmon (Salmo salar) in the River Klarälven, Sweden and brown trout (Salmo trutta) in the River Gudbrandslågen, Norway, and the influence of prior experience on passage success in 2012 and 2013. In the River Klarälven, fishway efficacy varied from 18 (2012) to 88% (2013). Most salmon (81%) entered the fishway trap on days without spill, and salmon moved from the turbine area to the spill zone when there was spill, with small individuals showing a stronger reaction than large fish. Analysis of fish with and without prior trap experience showed that a higher percentage of the “naïve” fish (70% of salmon and 43% of the trout) entered the fishway traps than the “experienced” ones (25% of the salmon and 15 % of the trout). Delays for fish that entered the trap ranged from 3-70 days for salmon and 2-47 days for trout, and there was no difference in median delay between naïve and experienced fish for each species. Manual positioning of radio-tagged salmon revealed that 11% of the naïve fish and 50% of the experienced fish ceased migration after tagging and release. In addition, a greater percentage of the salmon that were captured, marked and released in the lake attempted to enter the fishway (70%) than lake-caught salmon that were also transported 10km to the stream before release (33%). The data based on manual positioning and lake caught salmon indicate that differences in behavior of naïve and experienced individuals are likely stress-related. Moreover, our results suggest that estimates of fishway efficacy using fish with prior fishway experience may be biased, and based on our study, efficacy is underestimated.

  • 8.
    Hutchings, Jeffrey A.
    et al.
    Dalhousie University, Canada; Flødevigen Marine Research Station, Norway; University of Agder, Norway.
    Ardren, William R.
    Western New England Complex, USA.
    Barlaup, Björn T
    Norwegian Research Centre, Norway.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Clarke, Keith D.
    Fisheries and Oceans Canada, Canada.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Lake, Colin
    Glenora Fisheries Station, Canada.
    Piironen, Jorma
    Natural Resources Institute Finland (Luke), Finland.
    Sirois, Pascal
    Université du Québec à Chicoutimi, Canada.
    Sundt-Hansen, Line E
    Université du Québec à Chicoutimi, Canada.
    Fraser, Dylan J.
    Concordia University, Canada.
    Life-history variability and conservation status of landlocked Atlantic salmon: an overview2019In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 76, no 10, p. 1697-1708Article in journal (Refereed)
    Abstract [en]

    Nonanadromous Atlantic salmon (Salmo salar) exhibit a combination of variation in life history, habitat, and species co-existence matched by few vertebrates. Distributed in eastern North America and northern Europe, habitat ranges from hundreds of metres of river to Europe’s largest lakes. As juveniles, those with access to a lake usually migrate to feed and grow prior to reproduction. Prey such as smelt (Osmerus mordax, Osmerus eperlanus) and vendace (Coregonus albula) facilitate large body size (50–85 cm at maturity) and persistence in high-diversity (>20 fish species) environments; small-bodied salmon (10–30 cm at maturity), relying on insects as prey, coexist with few (fewer than five) other fishes. At maturity, weight varies more than 400-fold (17 to 7200 g) among populations, fecundity more than 150-fold (33 to 5600), and longevity almost fivefold (3 to 14 years). Landlocked salmon are managed to support sustainable fishing, achieve conservation and restoration targets, and mitigate threats; successes are evident but multiple challenges persist. Extraordinary variability in life history coupled with extensive breadth of habitat and species co-existence render landlocked Atlantic salmon singularly impressive from a biodiversity perspective.

  • 9.
    Jones, Douglas A.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Univ Otago, Dept Zool, Dunedin 9054, New Zealand..
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Food availability in spring affects smolting in brown trout (Salmo trutta)2015In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 72, no 11, p. 1694-1699Article in journal (Refereed)
    Abstract [en]

    Prior to out-migration, salmonid fish typically undergo physiological and morphological changes-a process known as smolting. This study indicates that smolting in brown trout (Salmo trutta) is affected by feeding conditions in spring immediately prior to out-migration. This conclusion was reached after experimentally testing the effect of seasonal variation in food availability on smolt status in the spring. A migratory strain of trout was administered either high or low food rations in the autumn, winter, or spring prior to release in the spring. While fish growth or condition could be affected in any season, it was spring rationing that reduced growth and growth-related variables and that caused increased smolting. Our result supports the idea that smoltification and the decision to migrate is affected by spring food availability regardless of conditions in the previous autumn or winter.

  • 10. Jonsson, Bror
    et al.
    Finstad, Anders G.
    Jonsson, Nina
    Winter temperature and food quality affect age and size at maturity in ectotherms: an experimentaltest with Atlantic salmon2012In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 69, no 11, p. 1817-1826Article in journal (Refereed)
    Abstract [en]

    Field studies have revealed that many ectotherms mature younger and smaller in warmer environments although they grow faster. This has puzzled ecologists because the direct effect of factors that accelerate growth is expected to be larger, not smaller size. We tested this experimentally for Atlantic salmon (Salmo salar) at two winter temperatures and diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

    Salmo salar) at two winter temperatures and

    diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the

    probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and

    high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of

    maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and

    between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is

    the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at

    maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

  • 11.
    Jönsson, Mikael
    et al.
    Lund University.
    Ranåker, Lynn
    Lund University.
    Nilsson, P. Anders
    Lund University.
    Brönmark, Christer
    Lund University.
    Foraging efficiency and prey selectivity in a visual predator: differential effects of turbid and humic water2013In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 70, no 12, p. 1685-1690Article in journal (Refereed)
    Abstract [en]

    Predators exert strong regulating forces on lower trophic levels through predation. As most fish are visual foragers, visual conditions in the water may alter the strength of this regulation. We evaluated effects of turbidity and humic water on foraging efficiency and prey-size selectivity in Northern pike (Esox lucius) feeding on roach (Rutilus rutilus). Encounter rates decreased in both turbid and humic water but were not counteracted by increased searching activity. Capture success was unaffected by turbidity but was nonlinearly affected by humic water by being high in clear and highly humic water but low in less humic water. In highly humic water, the visual range approached pike's strike distance and, together with its cryptic colours, pike may have initiated its attack before the prey detected it, limiting the possibility for prey evasive manoeuvres. Prey-size selectivity towards small prey in clear water disappeared in turbid water but was maintained in humic water. Owing to its optical properties, turbidity degrades the quality of the visual information more through scattering than humic water does through absorption. We show that the effect of visual degradation on foraging depends on the cause of visual degradation, which has not previously been acknowledged in the visual foraging literature.

  • 12.
    Naslund, Joacim
    et al.
    University Gothenburg, Sweden.
    Rosengren, Malin
    University Gothenburg, Sweden.
    Del Villar, Diego
    Technical University Denmark, Denmark.
    Gansel, Lars
    SINTEF Fisheries & Aquaculture, Trondheim, Norway.
    Norrgard, Johnny R.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Persson, Lo
    Swedish University Agricultuaral Sciences, Sweden.
    Winkowski, John James
    Canada.
    Kvingedal, Eli
    Norway.
    Hatchery tank enrichment affects cortisol levels and shelter-seeking in Atlantic salmon (Salmo salar)2013In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 70, no 4, p. 585-590Article in journal (Refereed)
    Abstract [en]

    Stocking programs using hatchery-reared salmon are often implemented for augmenting natural populations. However, survival of these fish is often low compared with wild conspecifics, possibly because of genetic, physiological, and behavioural deficiencies. Here, we compared presmolt Atlantic salmon (Salmo salar) from three different environmental treatments (barren environment, plastic tube enrichment, and plastic shredding enrichment) with regard to plasma cortisol levels, shelter-seeking behaviour, and fin deterioration. Basal plasma cortisol levels were higher in barren-reared fish, indicating higher stress levels, while no differences were found in acute cortisol response after a 30 min confinement test. Shelter-seeking was higher in salmon reared in enriched tanks when tested alone, but not when tested in small groups. Barren-reared fish had higher levels of fin deterioration over winter, potentially owing to higher aggression levels. These results suggest that enrichment can reduce the impact of stressors experienced in the hatchery and thus increase fish welfare. Tank enrichment may also be used to produce salmon better adapted for the more complex environment encountered after release.

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