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  • 301.
    Lans, Linnea
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Metcalfe, Neil
    Glasgow University.
    The cost of being aggressive: a comparison of winners and losers of territorial contestsManuskript (preprint) (Annet vitenskapelig)
  • 302. Liinansaari, T.
    et al.
    Calles, Olle
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Use of Passive Integrated Transponder technology in salmon and trout ecology. Final report. SEED Nordforsk2008Rapport (Fagfellevurdert)
  • 303. Lindgren, Johan
    et al.
    Currie, Philip. J.
    Siverson, Mikael
    Cederström, Peter
    Lindgren, Filip
    Rees, Jan
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    The first neoceratopsian dinosaur remains from Europe2007Inngår i: Palaeontology 50, 929-937Artikkel i tidsskrift (Fagfellevurdert)
  • 304. Lindgren, Johan
    et al.
    Rees, Jan
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Siverson, Mikael
    Cuny, Gilles
    The first Mesozoic mammal from Scandinavia2004Inngår i: GFF 126, 325-330, Vol. 126, s. 325-330Artikkel i tidsskrift (Fagfellevurdert)
  • 305.
    Lindh, Sara
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Solinstrålningens påverkan på växtsamhällen i kantzoner vid rinnande vatten: En jämförelse av artdiversitet, artsammansättning och funktionella gruppers sammansättning2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    ABSTRACT

    Streamside forests represent complex microhabitats. The Swedish forest agency includes conservation of these habitats in their aim for a sustainable forestry. Despite these guidelines deforestation in stream-side areas continues. Certain groups of plants in the riparian habitats are negatively affected by clear-cutting. The purpose of this study was to compare species diversity, species composition and functional group composition among plant communities with different amounts of solar radiation in boreal stream-side forests. Field inventories were made in three different categories of solar radiation, one category of high solar radiation, one category of moderate solar radiation and one category of low solar radiation. Eight plots of four square meters were inventoried in each category. Plant species and plant cover as well as a short description of the area was recorded for each sample plot. A total number of 60 species were found. Species diversity, species composition and functional group composition were compared among the different categories using statistical tests. There were no significant differences between the three categories in the total effective number of plant species. However, there were significant differences between the categories in the effective number of bryophyte species, with the lowest species number in the category of high solar radiation. Ellenberg's indicator values for light were used to analyze species composition. There were significant differences in the species composition of vascular plants between the categories with more species indicating a brighter environment in the category of high solar radiation and more species indicating a darker environment in the two other categories. There were no significant differences between the categories in the distribution of the functional groups of bryophytes, grasses, herbs and shrubs. There were significant differences in the distribution of the functional groups of bryophytes and vascular plants among the categories. The number of bryophytes species was highest in the category of low solar radiation and lowest in the category of high solar radiation while the number of vascular plants was highest in the category of high solar radiation and lowest in the category of moderate solar radiation. The lack of correlation between the total effective number of species and solar radiation is supported to some extent by earlier study results. The significant difference in the effective number of bryophyte species between the categories is in contrast to previous studies. One explanation could be the succession and fluctuation following clear-cutting. This means that the bryophyte flora may increase with time. The significant difference in species diversity between the categories confirms previous surveys and the hypothesis that the species diversity of plant communities varies in relation to solar radiation. Deforestation causes a shift of species in which light tolerant species replaces shade tolerant species. The distribution of the functional groups of bryophytes, grasses, herbs and shrubs lacks significant differences between the categories. This in contrast to other study results. One explanation may be that other measurement methods used. The result can also be affected by the season. Most vascular plants were small and undeveloped. The results of this study show that clearcutting along streamsides should be avoided if species composition, number of moss species and functional groups composition shall be preserved after deforestation. 

     

  • 306.
    Linlökken, Arne
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Prøvefiske og ekkoloddregistreringer i Osensjøen 20092009Rapport (Fagfellevurdert)
  • 307.
    Linlökken, Arne
    et al.
    Hamar Norway.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of temperature and roach Rutilus rutilus group size on swimming speed and prey capture rate of perch Perca fluviatilis and R. rutilus2010Inngår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 76, nr 4, s. 900-912Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effects of temperature and group size of roach Rutilus rutilus on foraging behaviour of perch Perca fluviatilis and R. rutilus were tested in two laboratory experiments. A temperature experiment with P. fluviatilis and R. rutilus in aquaria (with either one P. fluviatilis or two R. rutilus) was tested at five temperatures: 4, 8, 12, 16 and 20° C, and showed that P. fluviatilis had a lower swimming speed and capture rate than R. rutilus, especially at 4 and 8° C. The effect of group size was tested at four R. rutilus abundances: 0, 2, 4 and 6, all at 16° C, and revealed that swimming speed and capture rate of P. fluviatilis were lowest at the highest R. rutilus abundance, whereas R. rutilus was relatively unaffected. Perca fluviatilis occupied positions closer to the bottom than R. rutilus, especially when feeding, and this tendency was reinforced at the highest roach abundance

  • 308.
    Linlökken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Myromslien, Frøydis
    Johansen, Brit Rønning
    Gaustad, Ann-Helen
    Semen in the laser beam2009Konferansepaper (Fagfellevurdert)
    Abstract

    This study is a collaboration between Hedmark University College and Norsvin, the Norwegian artificial insemination (AI) boar company. Norsvin has a breeding program including the following breeds: Norwegian Landrace, Duroc, and Yorkshire. Sperm quality in breeding herds is of great economic importance. The classical methods for sperm quality evaluation are generally based on the examination of sperm concentration, motility and morphology. At Norsvin AI station, sperm concentration is routinely measured with a spectrophotometer. In addition, a light microscopy is used to exam motility and morphology. These evaluations are poor in predicting sperm quality and fertility, because only the samples with markedly poor quality can be detected. Flow cytometry, in combination with a variety of fluorochromes and compounds conjugated to fluorescent probes, has been shown to be a more objective and accurate method to evaluate sperm quality

  • 309.
    Linløkken, Arne
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Population ecology of perch (Perca fluviatilis) in boreal lakes2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    I studied the effects of temperature, pH, competition and predation on Eurasian perch (Perca fluviatilis) in 30 lakes in Norway during 1981-2001. The study lakes were situated in two different areas in southern Norway; four lakes in Aust-Agder county in southernmost Norway were explored during 1981-1984 and 26 lakes in Hedmark county in south-eastern Norway were investigated during 1992-2001. The study lakes varied considerably in pH, temperature, fish species composition, and perch abundance and size composition. In addition to field surveys, behavioural studies of perch were conducted at Karlstad University in 2006-2007.

    The field studies revealed that temperature affected recruitment of perch as strong year-classes of perch generally occurred in summers with high temperatures. Temperature also affected perch behaviour as indicated by the low gillnet catches (CPUE) of perch atlow temperature. This effect on CPUE was also supported by results from the aquaria experiments, where swimming and feeding activity of perch was low at low temperature. In a study of four lakes, growth was positively related to temperature in the lake with an allopatric perch population, but not in three lakes where perch occurred sympatrically with roach.

    pH also affected recruitment. In the four lakes in Aust-Agder, one strong year-class of perch occurred in all lakes in a year with especially high pH in spring and early summer. Adult mortality was also affected by pH, as old perch were less abundant in lakes with late spring pH=5.5-5.8 than in lakes with pH<5.5 and pH>5.8. The size and growth of adult perch were negatively affected by low pH, whereas abundance of large, potentially predatory perch was positively related to pH.

    The field studies indicated that roach influence perch populations. When coexisting with roach, perch were mainly littoral. In lakes where roach dominated (by number), there was no growth – temperature correlation, but there was such a correlation in lakes without roach. In lakes with sympatric roach, age-specific weight of perch and the growth of 2+ perch were negatively related to the proportion of roach in the gillnet catches. In the aquaria experiments, swimming and feeding activity of perch were lower than that of roach at all temperatures tested, and the difference was most pronounced at 4 and 8 °C. The aquaria experiments indicated that perch had a lower feeding efficiency and that they generally occupied positions closer to the bottom than roach.

  • 310.
    Linløkken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of temperature and group size on swimming speed and capture rate of perch (Perca fluviatilis) and roach (Rutilus rutilus).Manuskript (Annet vitenskapelig)
  • 311.
    Linløkken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Holt Seeland, Per Arne
    Environmental correlates of population variables of perch (Perca fluviatilis) in boreal lakes2008Inngår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 82, nr 4, s. 401-408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We examined relationships among perch population variable parameters in two types of lakes, lakes with perch (P-lakes, n = 15) and lakes with perch and roach (PR-lakes, n  = 10) using redundancy analysis (RDA) to relate population variables to environmental factors. Effects from environmental factors were tested for significance by means of permutation tests (Monte Carlo). Three factors, pH, altitude and fraction of roach (by number) in the gill net catches, explaining 47.9% of the variation, had significant effects on perch population variables. The significance of pH was improved by partialing out the effect of conductivity and roach. Similarly, the significance of altitude was improved by partialing out the effect of pH and roach, and the significance of roach was improved by partialing out the effect of pH and altitude. When the fraction of pike in the catch was included in the analysis, the effect of roach was not significant and vice-versa, as roach and pike fractions were correlated with each other. The effect of pike was significant when roach was not included, but the effect was not as strong as the effect of roach. A biplot was constructed by plotting population variables on the first and second RDA axis, with arrows showing five selected environmental factors. Growth of 3+ to 5+ perch was positively related to pH and altitude, perch catch per unit effort was negatively related to pH and altitude, and age specific perch weight was negatively related to fraction of roach. The relationship between growth of 2+ perch and pH was not as strong as the relationship between pH and the growth of older perch. Moreover, the growth of 2+ perch was negatively related to the fraction of roach, probably due to competition between young zooplankton feeding perch and roach.

  • 312.
    Linløkken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Hesthagen, Trygve
    Norwegian Instiute of Nature Research, Trondheim, Norway.
    Environmental effects on size and growth of perch (Perca fluviatilis) and roach (Rutilus rutilus)Manuskript (Annet vitenskapelig)
  • 313.
    Lund Bjørnås, Kristine
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Railsback, Steven F.
    Humboldt State University.
    Calles, Olle
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Piccolo, John
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Modeling Atlantic salmon (Salmo salar) and brown trout (S. trutta) population responses and interactions under increased minimum flow in a regulated riverManuskript (preprint) (Annet vitenskapelig)
  • 314.
    Lund Bjørnås, Kristine
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Railsback, Steven F.
    Humboldt State University.
    Piccolo, John
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Modifying and parameterizing the individual-based model inSTREAM for Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in the regulated Gullspång River, SwedenManuskript (preprint) (Annet vitenskapelig)
  • 315.
    Lundberg, Ida
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Flodpärlmusslans (Margaritifera margaritifera) påverkan på öringens (Salmo trutta) födosök och rörelsemönster2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Öringens gälar (Salmo trutta) fungerar inte bara som ett andningssystem för fisken utan också som ett fastsättningsställe för flodpärlmusslans (Margaritifera margaritifera) parasitiska larver. Larverna kallas glochidielarver och när de släpps ifrån modermusslan måste de hitta sin värd relativt snabbt för att inte dö. Om de lyckas hitta sig en öring så fäster de sig på fiskens gälar där de sedan kapslas in av fiskens epitelceller. Glochidielarverna lever sedan där i ca 3-10 månader främst beroende på temperaturen. Eftersom mussellarven är en parasit tar den sin näring och energi ifrån värdfisken.

    I denna studie undersöktes skillnader mellan låginfekterade och höginfekterade odlade öringar (+0, medelvikt 1,77g +/- 0,11) och hur deras beteende skilde sig åt när det gäller rörlighet och antal fångade byten. Fiskarna testades både individuellt och i par. Experimentet utfördes i ett strömakvarium och hypoteserna var att låginfekterade öringar tar fler byten än höginfekterade, och att de individuella fiskarna tar mer byten än fiskarna i par. Det undersöktes också i vilken omfattning fiskarna simmade uppströms eller nedströms när de fångade sina byten och om det var någon skillnad mellan låg- och höginfekterade öringar. Resultatet visade att det fanns en signifikant skillnad (p=0,0046) mellan låg- och höginfekterade öringar när det gäller antal tagna byten, där låginfekterade öringar tar mer byten än höginfekterade. Det fanns igen signifikant skillnad mellan antlal simrörelser nedströms/uppströms mellan låg- och höginfekterade, däremot fanns det en signifikant skillnad (p=0,0027) mellan antal simrörelser uppströms och nedströms oavsett låg- eller höginfekterad, där det visade sig att öringen simmar mer nedströms än uppströms från sin focal point när den fångar byten. När det gäller antal tagna byten hos de individuella fiskarna vs. fiskarna i par, så tog de individuella fiskarna fler byten än vad var och en av fiskarna i par gjorde (medeltal: fiskar i par 28, individuella 36), men det fanns ingen signifikant skillnad (p=0,06). Utifrån resultaten kan man antyda att infektering av flodpärlmusslans glochidielarver kan ha en negativ effekt på öringens fysiska prestanda. Öringen får mindre energi till födosök och därmed sämre förutsättningar till t.ex. tillväxt. 

  • 316.
    Lundsten, Emelie
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Barns kunskaper om djurarter: Kan kunskaperna skilja beroende på vart man bor?2011Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    This study is about differences in knowledge regarding animals. In the study five year old preschool children from a city were compared to five year old preschool children in the suburbs with multicultural background. The study is also about where children´s knowledge about animals comes from and how educators can make a positive difference. To find this out standardized interviews was used on 23 children from four different preschools, two preschools in the suburbs with 15 children and two preschools in the city with 13 children. A survey was sent out to the educators within these preschools to gather background information on what the children do regarding animals. The results from the interviews made it clear that there were differences in the knowledge about different animals. Almost every child in the suburbs had difficulties to mention 10 animals. In the city on the other hand all the children except one mentioned more than 10 animals. A wide variation of animals was mentioned by the children in this study, in the suburbs domestic and farm animals was mostly mentioned while it was mostly exotic animals mentioned in the city. A possible causal explanation for the findings may be differences of language, nature, habit and culture.

  • 317.
    Lönnbring, Gunilla
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för sociala studier.
    Stolare, Martin
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för politiska och historiska studier. Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för de samhällsvetenskapliga ämnenas didaktik.
    Arvidsson, Björn
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bilder av Värmland2007Bok (Fagfellevurdert)
  • 318. MacKenzie, A.
    et al.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    The influence of instream cover and predation on microhabitat selection of stone loach Barbatula barbatula1998Inngår i: Ecology of Freshwater Fish 7: 87-94Artikkel i tidsskrift (Fagfellevurdert)
  • 319. Malick, Michael J.
    et al.
    Haldorson, Lewis J.
    Piccolo, John
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Boldt, Jennifer L.
    Growth and survival in relation to body size of juvenile pink salmon in the northern Gulf of Alaska2011Inngår i: Marine and Coastal Fisheries, ISSN 1942-5120, Vol. 3, nr 1, s. 261-270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The abundance of anadromous salmon is partially determined by size-selective mortality during the early marine life phase. Consequently, identifying the growth patterns of juvenile salmon during this life phase is important in understanding the dynamics of salmon populations. We examined patterns of early marine growth in juvenile pink salmon Oncorhynchus gorbuscha released by four hatcheries in Prince William Sound (PWS), Alaska, and explored how these patterns related to marine survival. Since larger individuals are thought to experience reduced mortality, we partitioned the data into weight-based quartiles and compared growth rates (% body weight/d) of all fish, the largest fish (top 25%), and the smallest fish (bottom 25%). Sampling occurred during summer 1997–2004 in PWS, the inshore Gulf of Alaska (GOA), and the offshore GOA. Growth rates varied significantly among years and sampling locations; however, the growth rate patterns were markedly similar among size-groups and hatcheries. Growth rates tended to be high in 1997, 2002, and 2004 and lower in 1998, 2001, and 2003. Fish sampled in the offshore GOA typically had faster growth rates than those sampled elsewhere, although this was less pronounced for the largest fish. For all size-groups, the relationship between survival and growth rate was strongest for fish captured in the offshore GOA and weakest for those captured in PWS, indicating that the likelihood of survival is greater for juveniles that migrate offshore earlier. The strength of the growth rate–survival relationship for pink salmon captured in the offshore GOA was similar among all size-groups, suggesting that once fish migrate offshore they are less vulnerable to size-selective predation.

  • 320. Malick, M.J
    et al.
    Haldorson, L
    Piccolo, John
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Characterizing Habitat Specific Size, Condition, and Growth of Juvenile Pink Salmon in the Northern Gulf of Alaska2009Konferansepaper (Fagfellevurdert)
  • 321.
    Marker, Jeffery
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of distance to urban areas on saproxylic beetles in urban forests2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Urban forests play key roles in animal and plant biodiversity and provide important ecosystem services.  Habitat fragmentation and expanding urbanization threaten biodiversity in and around urban areas.  Saproxylic beetles can act as bioindicators of forest health and their diversity may help to explain and define urban-forest edge effects.  I explored the relationship between saproxylic beetle diversity and distance to an urban area along nine transects in the Västra Götaland region of Sweden.  Specifically, the relationships between abundance and species richness and distance from the urban-forest boundary, forest age, forest volume, and tree species ratio was investigated Unbaited flight interception traps were set at intervals of 0, 250, and 500 meters from an urban-forest boundary to measure beetle abundance and richness.  A total of 4182 saproxylic beetles representing 179 species were captured over two months.  Distance from the urban forest boundary showed little overall effect on abundance suggesting urban proximity does not affect saproxylic beetle abundance.  There was an effect on species richness, with saproxylic species richness greater closer to the urban-forest boundary.  Forest volume had a very small positive effect on both abundance and species richness likely due to a limited change in volume along each transect.  An increase in the occurrence of deciduous tree species proved to be an important factor driving saproxylic beetle abundance moving closer to the urban-forest.  Overall, analysis showed inconsistent effects on both abundance and richness as functions of proximity to the urban-forest boundary.  Urban edge effects, forest volume, forest age, and forest tree species make up are all variables that may effect saproxylic abundance and species richness.  Forest managers should consider these variables when making management decisions.

  • 322. Nathansson, J-E.
    et al.
    Calles, Olle
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Vandringsstudie på mal (Silurus glanis), genom omlöpet vid Finsjö övre, Emån2008Rapport (Fagfellevurdert)
  • 323.
    Norrgård, Johnny
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Downstream migration of wild and hatchery-reared smolts of Salmo salar and Salmo trutta in River Klarälven2009Konferansepaper (Fagfellevurdert)
  • 324.
    Norrgård, Johnny
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Schmitz, Monika
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effects of feeding regimes and early maturation on migratory behaviour of landlocked hatchery-reared Atlantic salmon Salmo salar smolts2014Inngår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 85, nr 4, s. 1060-1073Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature males, which had matured the previous autumn, were also tagged and released. To monitor migration of the fish, acoustic receivers were deployed along the migratory route. The proportion of S. salar that reached Lake Vänern was significantly greater for fish fed fat-reduced feed than for fish given rations with higher fat content, regardless of ration size. Fish from the early mature male group remained in the river to a greater extent than fish from the three feeding regimes. Smolt status (degree of silvering), as visually assessed, did not differ among the feeding regime groups, and moreover, fully-silvered fish, regardless of feeding regime, migrated faster and had a greater migration success than fish with less developed smolt characteristics. Also, successful migrants had a lower condition factor than unsuccessful ones. These results indicate that the migration success of hatchery-reared S. smolts released to the wild can be enhanced by relatively simple changes in feeding regimes and by matching stocking time with smolt development.

  • 325.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Downstream migration of landlocked salmon Salmo salar smolts through multiple dams, river Klarälven, Sweden2011Konferansepaper (Fagfellevurdert)
  • 326.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Landlocked Atlantic salmon Salmo salar L. and trout Salmo trutta L. in the regulated River Klarälven, Sweden: Implications for conservation and management2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Conservation and management of migratory salmonids requires an understanding of their ecology at multiple scales, and a holistic view, including assessment of historical and present anthropogenic impacts. In the regulated River Klarälven, with 11 hydropower dams, populations of landlocked Atlantic salmon Salmo salar and migratory brown trout Salmo trutta have declined due to human activities. Maintaining viable populations of salmon in the River Klarälven has high priority, given there are fewer than 10 native stocks of landlocked salmon in Europe. To date, natural smolt production has been maintained by collecting and transporting spawners past eight hydroelectric plants in the river, where they are released to spawn. No functioning fish passage facilities are available that allow the fish to return to the lake. To evaluate the situation for landlocked salmon and migratory trout in Lake Vänern and the River Klarälven, an analysis of catch and river return data, based on data sets covering time periods from 15 to 200 years, was performed. In addition, the loss rates and behavior of downstream-migrating wild salmon smolts as they swam past eight power stations in the regulated River Klarälven was quantified.

    For the migration study, wild salmon smolts were tagged with acoustic transmitters, and the smolts were monitored as they swam along a 180 km long river segment, including eight dams, with regulated and unregulated stretches. The loss due to HEP passages was estimated to be 76%, which contrasts with the 8% loss along unregulated control stretches. Kaplan-Meier estimations showed that only 16% of the smolts passed all eight dams. Migration speed was 83% lower along regulated stretches than along unregulated stretches, and migration speed at regulated stretches was dependent on fish size, with large fish moving slower than small fish.

    The analysis of historical data showed that annual returns of wild salmon are less than 3% of what they were at the beginning of the 19th century. Returns of wild trout are even lower, with just some 30 fish caught annually. Lack of basic ecological information, as river return and fisheries catch rates, estimates of wild smolt production and survival, and releases of hatchery-reared fish, complicate an effective management of these unique populations. There is need for coordination of present and future research, monitoring, and restoration strategies. In this thesis I identify some measures to improve the status of the River Klarälven salmon and trout that should be of broad interest to resource and fishery managers.

  • 327.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Multiplicative loss of Salmo Salar L. smolts during downstream migration through multiple dams2012Konferansepaper (Fagfellevurdert)
  • 328.
    Norrgård, Johnny R
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Adam, Ludvigsson
    Länsstyrelsen i Västra Götalands län, Vänersborg, Sverige.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Predation by northern pike Esox lucius on migrating hatchery-reared salmonid smoltsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Supplementary stocking of hatchery-reared smolts is the main method used to mitigate and compensate for lost production of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) populations in rivers. The survival of hatchery reared smolts in nature is generally low, and predation is one explanation for this. In the River Klarälven, Sweden, approximately 175 000 hatchery reared salmon and trout smolts are annually released into the rivr approximately 25 km upstream of Lake Vänern, to where they migrate and remain until maturity. During 2006-2010 half of the released hatchery reared smolts tagged with telemetry transmitters did not reach Lake Vänern. The loss rate of smolts was higher in river reaches with shallow vegetated areas and in reaches with deep pool areas than in the dominant habitat type, consisting of intermediate depths and sandy, uniform bottom substrates. Similarly, average CPUE of northern pike (Esox Lucius) was high in the same habitats as where smolts were lost. Gut content analyses of pike showed that they fed chiefly on European smelt (Osmerus eperlanus) in April, hatchery-reared salmonid smolts in May and European river lamprey (Lampetra fluviatilis) in June. We argue that when these different energy and lipid rich alternative prey occur at high densities during their spawning periods they are probably an easily caught energetically favorable prey. Our results indicate that there may be ecological windows of opportunity for stocking hatchery-reared smolts that could increase survival in the River Klarälven.

  • 329.
    Norrgård, Johnny R
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry A
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Piccolo, John J
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Schmitz, Monika
    Uppsala university.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Multiplicative loss of landlocked Atlantic salmon Salmo salar L. smolts during downstream migration through multiple dams2013Inngår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 29, nr 10, s. 1306-1317Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Relatively little is known about the downstream migration of landlocked stocks of Atlantic salmon Salmo salar L. smolts, as earlier migration studies have generally focused on upstream migration. However, in watersheds with many hydroelectric plants (HEPs), multiplicative loss of downstream-migrating salmon smolts can be high, contributing to population declines or extirpations. Here we report the results from a study of wild landlocked Atlantic salmon smolts in the River Klaralven. Salmon smolts, tagged with acoustic transmitters, were released at different locations and followed as they passed 37 receivers along a 180-km-long river segment, including eight dams as well as free-flowing control stretches. We found that 16% of the smolts successfully migrated along the entire river segment. Most losses occurred during HEP passages, with 76% of the smolts being lost during these passages, which contrasts with the 8% smolt loss along unregulated control stretches. Migration speed was 83% slower along regulated stretches than along unregulated stretches. The observed lower migration speed at regulated stretches was dependent on fish size, with large fish moving slower than small fish. Discharge affected migration speed but not losses. As previously shown for anadromous populations, our study of landlocked salmon demonstrates similar negative effects of multiple passages of HEPs by downstream-migrating smolts. On the basis of this and previous migration studies, we advocate using a holistic approach in the management and conservation of migratory fish in regulated rivers, which includes safe passage for both upstream- and downstream-migrating fish. Copyright (c) 2012 John Wiley & Sons, Ltd.

  • 330.
    Nyberg, Lars
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för klimat och säkerhet.
    Andersson, Jan-Olov
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Mörth, Carl-Magnus
    Dept of Geology and Chemistry, Stockholm University.
    Malmström, Maria
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Influence of wetland restoration on hydrology and water chemistry in a Swedish boreal catchmentManuskript (Annet vitenskapelig)
  • 331.
    Nyberg, Lars
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för klimat och säkerhet.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bladh, Gabriel
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för geografi och turism. Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Centrum för de samhällsvetenskapliga ämnenas didaktik.
    Vatten i skogslandskapet2004Inngår i: Inte bara träd – hållbart mångbruk av skogslandskapet / [ed] Olsson, Nyberg, Bladh och Månsson, Stockholm: Carlssons förlag , 2004Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 332.
    Nyberg, Lars
    et al.
    Karlstads universitet, Institutionen för natur och miljö.
    Calles, Olle
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Impact of short-term regulation on hyporheic water quality in a boreal river2008Inngår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 24, nr 4, s. 407-419Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water regulation may alter hydraulic head gradients with consequences for the exchange of water between the river and the hyporheic zone. The objective of this study was to investigate the effect of discharge on hyporheic water quality in a regulated Swedish boreal river during a 10-day experimental period with a sequence of alternating high- and low-flow episodes. A 250 m reach was instrumented with 28 piezometers placed at 150 and 300 mm below the river bed or below the mean groundwater level in the floodplain, and these piezometers were used to measure temperature, oxygen, electric conductivity and pH. High daily variation in air temperature during the first 3 days was transmitted vertically through the stream water into the hyporheic zone within hours. An oxygen saturation of 100% in the river water corresponded to 60–70% saturation at 150 mm depth and 30% at 300 mm depth. The hyporheic oxygen concentration at 150 mm depth decreased during the experimental period, falling into a range that is potentially harmful to incubating salmonid eggs. This was interpreted as a long-term response to the overall regulation regime, rather than a response to short-term water regulation during the experiment. Even though the effect of short-term regulation on the quality of hyporheic water in the river bed was limited, there was a more pronounced effect on the quality of floodplain hyporheic water. Most of the driving forces for temporal variation of water quality in the river bed came vertically from the river water, rather than from the lateral exchange.

  • 333.
    Nyqvist, Daniel
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Calles, Olle
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Bergman, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Hagelin, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Post-Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning?2016Inngår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 32, nr 5, s. 1008-1017Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, relatively little is known about this phase of the life history for anadromous populations, and nothing has been reported for landlocked populations. Here, we studied post-spawning behaviour and survival of landlocked Atlantic salmon in relation to downstream dam passage in the River KlarÀlven, Sweden. Eight hydropower stations separate the feeding grounds in Lake VÀnern from the spawning grounds in the River KlarÀlven, and no measures to facilitate downstream migration are present in the river. Forty-nine percent of the salmon survived spawning and initiated downstream migration. Females and small fish had higher post-spawning survival than males and large fish. The post-spawners migrated downstream in autumn and spring and remained relatively inactive in the river during winter. Downstream migration speed in the free flowing part of the river was highly variable with a median of 9.30km/day. Most fish passed the first hydropower station via upward-opening spill gates after a median residence time in the forebay of 25min. However, no tagged fish survived passage of all eight hydropower stations to reach Lake VÀnern. This result underscores the need for remedial measures to increase the survival of downstream migrating kelts.

  • 334. Olofsson, H.
    et al.
    Calles, Olle
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Fiskeplan för biologisk återställning av vattensystem i Söderhamns kommun: Fisheries management plan for Söderhamn municipality2003Rapport (Annet vitenskapelig)
  • 335.
    Olsson, Ivan
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of pond habitats on migrating brown trout (Salmo trutta L.) smolt1999Inngår i: Information from the National Board of Fisheries. 1999:5: 33-50. Report written in Swedish with English abstractArtikkel i tidsskrift (Fagfellevurdert)
  • 336.
    Olsson, Ivan
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Influence on Habitat on Migration in Brown Trout, Salmo trutta L: Fil. Lic. thesis2003Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The two papers presented in this thesis focus on different aspects of migration in brown trout.

    In paper I, I measured loss-rates and studied migratory behavior of brown trout as they swam through a newly created artificial lentic habitat, and compared these results with a reference section in the stream. I found higher loss-rates, an altered diel activity pattern and a slower swimming speed in the lentic habitat than in the stream section. Lentic habitats might therefore act as a barrier, contributing to higher costs for migrants. In paper II, I monitored a landlocked brown trout population in two lotic stream sections, geographically separated by a lentic habitat. In the upstream section, where density was low and growth rate high, most individuals did not migrate, whereas in the downstream section, where density was high and growth rate low, many individuals migrated. Thus, the decision to migrate depended on origin of the trout and seemed to be related to juvenile density and growth. In addition, the lentic habitat might have functioned as a barrier, selecting for residency in the upstream section.

  • 337.
    Olsson, Ivan
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Arvidsson, Björn
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Utvandring av klarälvslax från en utsättningsbassäng med förbindelse till Klarälven: Migration of the Klarälven salmon from a stocking pond into Klarälven2001Rapport (Fagfellevurdert)
  • 338.
    Olsson, Ivan
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of pond habitats on migrating brown trout smolt, 1996: Masters project. Lund University. Report written in Swedish with English abstract1997Rapport (Fagfellevurdert)
  • 339.
    Olsson, Ivan
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi. Länsstyrelsen i Skåne.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Life history tactics in cohorts of a partial migratory brown trout (Salmo trutta L.) population2011Inngår i: ISRN Ecology, ISSN 2090-4614, E-ISSN 2090-4622, Vol. 2011, nr 915239, s. 1-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We monitored temporal changes in body size for three cohorts of a partial migratory, lake-migrating brown trout population.Wetested if body mass differed between nonmigratory males, migrants, and other members of the cohort (females and immaturemales).We hypothesized that large-sized individuals would mature as nonmigratory males or migrate at younger ages than smallsizedindividuals. As previous studies have shown that female fecundity is influenced by body size and that more trout from thedownstream section (D) of the stream migrated than from the upstream section (U), we hypothesized that there would be a greaterproportion of mature males in D than U.We found that body size of males that reproduced was similar to migrants that migratedthe subsequent spring and larger than other cohort members. Reproducing males had a larger body size than equal-aged malesthat delayed reproduction. Similarly, individuals that migrated had a larger body size than equal-aged individuals that migratedsubsequently. The proportion of mature males was greater in D than in U. The fact that body size differentiation occurred late inontogeny and that age of maturation and migration varied within cohorts suggests that the decision to mature or migrate mightbe conditionally dependent.

  • 340.
    Olsson, Ivan
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Partial migration in a landlocked brown trout population2004Inngår i: Journal of Fish Biology 65: 106-121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Population densities of landlocked lakemigratory brown trout Salmo trutta were estimated in two distinct lotic sections, separated by a lentic segment, in the Greåna River, Sweden, and individual growth and habitat use were monitored for 835 tagged brown trout from September 1998 to June 2000. Residency dominated in the upstream section where density of 0+ and 1+ year brown trout was low and growth rate high. In contrast, >90% of the brown trout that migrated to the lake originated from the downstream section, where density was high and growth rate low. For 2+ year individuals, growth rate was similar between the two stream sections, but densities were higher in the upstream than in the downstream section. Lakemigrants had higher growth rates than nonmigrants (residents) during the autumn of both years. From September to May, migrants increased their body mass by >35%, whereas nonmigrants increased by <5%. Approximately 70% of the brown trout moved <10 m and <2% moved between the two stream sections, indicating that the lentic habitat might function as a barrier for juveniles. Differences in migratory behaviour, density and growth between the upstream and the downstream section might indicate that environmental factors influence the decision to migrate. It cannot be excluded, however, that the observed differences are genetically programmed, selected by migration costs that favour migratory behaviour downstream and residency upstream.

  • 341.
    Olsson, Ivan
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Wysujack, Klaus
    Environmentally induced migration: the importance of food2006Inngår i: Ecology Letters 2006 9:645-651Artikkel i tidsskrift (Fagfellevurdert)
  • 342.
    Olsson, Ivan
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Eklöv, A.
    Effect of an artificial pond on migrating brown trout smolts2001Inngår i: North American Journal of Fisheries Management 21:498-506Artikkel i tidsskrift (Fagfellevurdert)
  • 343.
    Olsson, Mattias
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Cox, J.J.
    Larkin, J.L.
    Maehr, D.S.
    Widén, P.
    Wichrowski, M.
    Movement and activity patterns of reintroduced elk (Cervus elaphus nelsoni) on an active coal mine in Kentucky2007Inngår i: Wildlife Biology in PracticeArtikkel i tidsskrift (Fagfellevurdert)
  • 344.
    Olsson, Mattias
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Cox, John
    University of Kentucky, Department of Forestry, USA.
    Larkin, Jeff
    Indiana University of Pennsylvania, Department of Biology, USA.
    Widén, Per
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för hälsa och miljö.
    Olovsson, Anders
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Space and habitat use of moose in southwestern Sweden2011Inngår i: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, nr 2, s. 241-249Artikkel i tidsskrift (Fagfellevurdert)
  • 345.
    Olsson, Mattias
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Widén, Per
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effects of highway fencing and wildlife crossings on moose Alces alces movements and space use in southwestern Sweden2008Inngår i: Wildlife Biology, ISSN 0909-6396, E-ISSN 1903-220X, Vol. 14, nr 1, s. 111-117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Use of exclusion fencing is an effective method to reduce moose-vehicle collisions, and exclusion fences are commonly erected along Swedish highways. However, exclusion fences may pose a threat to the viability of wildlife populations because they serve as barriers to individual movements and may limit accessibility to resources. Various types of wildlife crossings intended to reduce road-kills and increase habitat connectivity across fenced highways have been constructed throughout the world. However, few studies have evaluated the effectiveness of these crossing structures with respect to movements before, during and after construction of highways and exclusion fencing. We studied movements of 24 GPS-collared moose Alces alces before, during and after an existing two-lane road was reconstructed to a fenced four-lane highway with three wildlife crossings designed for moose. We recorded 135 movements across the highway during 8,830 moose-monitoring days. Of these, 47 occurred before the construction began, 76 occurred during the construction, and 12 occurred after the highway was fenced. All movements registered after the fencing occurred across two of the three wildlife crossings. The average number of highway crossings per moose-day decreased by 67-89% after fencing. The number of moose-vehicle collisions decreased after the exclusion fencing, but the fenced highway served as a barrier to moose movements even though three wildlife crossings were created. Thus, exclusion fencing may reduce moose mortality and provide safer conditions for automobile travellers, but the fencing may have a negative impact on moose accessibility to resources, gene flow and recolonisation rates.

  • 346.
    Olsson, Mattias
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Widén, Per
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för hälsa och miljö.
    Larkin, Jeff
    Department of Biology, Indiana University of Pennsylvania, USA.
    Effectiveness of a highway overpass to promote landscape connectivity and movement of moose and roe deer in Sweden2008Inngår i: Landscape and Urban Planning, Vol. 85, nr 2, s. 133-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ungulate-vehicle accidents accounted for approximately 60% of the total police reported traffic accidents in Sweden during the 1990s. While exclusion fences are effective at reducing such collisions, they create a new threat to wildlife by limiting individual movements and access to resources. To promote movements across fenced highways, wildlife crossing structures have been constructed in many countries. We used infrared remote cameras, track count surveys, and GPS telemetry to monitor the use of a highway overpass by moose (Alces alces) and roe deer (Capreolus capreolus) in southwestern Sweden. Moose and roe deer used the overpass mostly during nocturnal hours (84 and 76%, respectively). Overpass use declined with increased traffic volume on the highway, indicating that highway traffic affected the frequency in which ungulates used the overpass. We calculated that 5–7 individual moose used the overpass annually which is enough to maintain gene flow between otherwise disjunct subpopulations.

  • 347. Orlikowska, Ewa H.
    et al.
    Piccolo, John
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    A biological risk assessment for an Atlantic salmon colonization in Alaska2007Rapport (Fagfellevurdert)
  • 348. Otero, Jaime
    et al.
    L'Abee-Lund, Jan Henning
    Castro-Santos, Ted
    Leonardsson, Kjell
    Storvik, Geir O.
    Jonsson, Bror
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi. Norsk institutt for naturforskning (NINA).
    Dempson, Brian
    Russell, Ian C.
    Jensen, Arne J.
    Bagliniere, Jean-Luc
    Dionne, Melanie
    Armstrong, John D.
    Romakkaniemi, Atso
    Letcher, Benjamin H.
    Kocik, John F.
    Erkinaro, Jaakko
    Poole, Russell
    Rogan, Ger
    Lundqvist, Hans
    MacLean, Julian C.
    Jokikokko, Erkki
    Arnekleiv, Jo Vegar
    Kennedy, Richard J.
    Niemela, Eero
    Caballero, Pablo
    Music, Paul A.
    Antonsson, Thorolfur
    Gudjonsson, Sigurdur
    Veselov, Alexey E.
    Lamberg, Anders
    Groom, Steve
    Taylor, Benjamin H.
    Taberner, Malcolm
    Dillane, Mary
    Arnason, Fridthjofur
    Horton, Gregg
    Hvidsten, Nils A.
    Jonsson, Ingi R.
    Jonsson, Nina
    McKelvey, Simon
    Naesje, Tor F.
    Skaala, Oystein
    Smith, Gordon W.
    Saegrov, Harald
    Stenseth, Nils C.
    Vollestad, Leif Asbjorn
    Basin-scale phenology and effects of climate variability on global timing of initial seaward migration of Atlantic salmon (Salmo salar)2014Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 20, nr 1, s. 61-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Migrations between different habitats are key events in the lives of many organisms. Such movements involve annually recurring travel over long distances usually triggered by seasonal changes in the environment. Often, the migration is associated with travel to or from reproduction areas to regions of growth. Young anadromous Atlantic salmon (Salmo salar) emigrate from freshwater nursery areas during spring and early summer to feed and grow in the North Atlantic Ocean. The transition from the freshwater ('parr') stage to the migratory stage where they descend streams and enter salt water ('smolt') is characterized by morphological, physiological and behavioural changes where the timing of this parr-smolt transition is cued by photoperiod and water temperature. Environmental conditions in the freshwater habitat control the downstream migration and contribute to within- and among-river variation in migratory timing. Moreover, the timing of the freshwater emigration has likely evolved to meet environmental conditions in the ocean as these affect growth and survival of the post-smolts. Using generalized additive mixed-effects modelling, we analysed spatio-temporal variations in the dates of downstream smolt migration in 67 rivers throughout the North Atlantic during the last five decades and found that migrations were earlier in populations in the east than the west. After accounting for this spatial effect, the initiation of the downstream migration among rivers was positively associated with freshwater temperatures, up to about 10 °C and levelling off at higher values, and with sea-surface temperatures. Earlier migration occurred when river discharge levels were low but increasing. On average, the initiation of the smolt seaward migration has occurred 2.5 days earlier per decade throughout the basin of the North Atlantic. This shift in phenology matches changes in air, river, and ocean temperatures, suggesting that Atlantic salmon emigration is responding to the current global climate changes.

  • 349. Persson, A.
    et al.
    Lundberg, P.
    Pettersson, L.
    Brönmark, C.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Hansson, L.-A.
    NilssonL, A.
    Nyström, P.
    Romare, P.
    Tranvik, L.
    Effects of enrichment on simple aquatic food webs2001Inngår i: Am. Nat. 157:654-669Artikkel i tidsskrift (Fagfellevurdert)
  • 350. Persson, L.
    et al.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Interspecific and intraspecific size-class competition affecting resource use and growth of perch (Perca fluviatilis )1990Inngår i: Oikos 59(1): 97-106Artikkel i tidsskrift (Fagfellevurdert)
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