A5067857337- Fish Ecology and Management Studies
- Marine and fisheries research
- Fish Biology and Ecology Studies
- Aquatic Invertebrate Ecology and Behavior
- Reproductive biology and impacts on aquatic species
- Aquaculture Nutrition and Growth
- Physiological and biochemical adaptations
- Genetic diversity and population structure
- Genetic and phenotypic traits in livestock
- Wildlife Ecology and Conservation
- Fish biology, ecology, and behavior
- Ecology and biodiversity studies
- Marine Bivalve and Aquaculture Studies
- European and International Law Studies
- Radioactive contamination and transfer
- Indigenous Studies and Ecology
- Animal Behavior and Reproduction
- Environmental DNA in Biodiversity Studies
- Soil and Water Nutrient Dynamics
- Marine animal studies overview
- Isotope Analysis in Ecology
- Peatlands and Wetlands Ecology
- Education, Healthcare and Sociology Research
- Botany and Plant Ecology Studies
- Avian ecology and behavior
Norwegian Institute for Nature Research
2015-2025
Karlstad University
2015-2024
Université de Montréal
2008-2010
Memorial University of Newfoundland
2010
Studsvik (Sweden)
2003
Hólar University College
2000
Directorate of Fisheries
1985
University of Oslo
1976-1983
Farm Atlantic salmon escape and invade rivers throughout the North annually, which has generated growing concern about their impacts on native populations. A large-scale experiment was therefore undertaken in order to quantify lifetime success interactions of farm invading a Norwegian river. Sexually mature were genetically screened, radio tagged released into River Imsa where no other had been allowed ascend. The fishes competitively reproductively inferior, achieving less than one-third...
Brown trout Salmo trutta in Vangsvatnet Lake, Norway, include freshwater residents that mature sexually without any sea run and migrants smoltify migrate between fresh water the one or more years before maturing. Migrants leave Lake during spring move coastal waters up to 100 km from lake outlet they return their home river summer autumn; older earlier than younger migrants, fish immatures. Both spawn together tributaries Lake. Young brown (parr) grow lake; dwellers faster stream dwellers....
The Arctic charr Salvelinus alpinus exhibits 1–4 sympatric morphs in postglacial lakes, of which one or two are epibenthic zoobenthos feeders, is a limnetic planktivore and piscivorous form. In addition, northern rivers support partly migratory populations with anadromous freshwater resident fish. vary their coloration, morphology, life history, behaviour genetic characteristics. usually differentiate according to ontogenetic stage at maturity, parallels paedomorphism amphibians. young start...
1. Escape of cultured organisms into natural ecosystems may threaten wild populations both ecologically and genetically. In the aquaculture industry, farmed Atlantic salmon (Salmo salar L.) often escape enter spawning grounds salmon. We report experiments to assess competitive reproductive abilities fifth-generation their potential impacts upon 2. The females had similar levels behaviour; however, they differed in behaviour success. Farmed displayed less breeding behaviour, constructed fewer...
1. There were marked changes in the relative lipid content of somatic and visceral tissues during course upstream migration spawning. The per 100 g wet tissue mass was high maturing salmon July (soma, pooled sexes: 12.1 g; viscera: 11.4g males 7.3 females) decreased to a minimum after spawning November (soma: 2.1 1.6 g). Percentages protein soma viscera relatively stable study period, ranging from 21.9 (soma) 16.3 (viscera) -1 fish September-October, 17.1 16-1 spent salmon. carbohydrate...
Lake Thingvallavatn supports four trophic morphs of Arctic charr, Salvelinus alpinus (L.); two the are benthic (small and large benthivorous charr) one exploits pelagic waters (planktivorous fourth is found in both habitats (piscivorous charr). The morphological variation among these was analysed by use principal component analysis canonical discriminant analysis. benihic have a short lower jaw long pectoral fins. fish also fewer gillrakers than other morphs. Small charrs attain sexual...
The coexistence of four morphs arctic charr in Thingvallavatn, Iceland, was demonstrated by investigations morphology, habitat use, diet, endoparasitic fauna, life history, time and place spawning, early ontogeny, population genetics. Head morphology embryos, juveniles adults revealed the presence two morphotypes, each including morphs: (1) a benthic morphotype large benthivorous (LB-) small (SB-) charr, featuring overshot mouth relatively pectoral fins, (2) pelagic planktivorous (PL-)...
We quantified divergence in phenotype of sea-ranched, farmed, and wild Atlantic salmon (Salmo salar) a common genetic stock (River Imsa, Norway). These first-generation fish were also contrasted with fifth-generation farmed population (Norwegian commercial strain) multigeneration sea-ranched populations coho (Oncorhynchus kisutch). In comparisons using mature male parr, cultured juveniles had smaller heads fins narrower caudal peduncles could be distinguished from 100% accuracy. When reared...
1. We explored the mechanisms determining age and size at juvenile migration in brown trout Salmo trutta L. A 133 Cs tracer methodology was used to estimate food consumption of a Norwegian stream, energy budgets early migrants stream residents were compared. 2. Fast‐growing migrated lake earlier smaller body than slower‐growing individuals. The 2+ significantly larger those that remained 1 or more years longer stream. 3+ migrants. Some fast‐growing males matured whereas all females left...
To examine the link between early experience and subsequent reproductive performance, we experimentally manipulated of Atlantic salmon (Salmo salar). Salmon a common genetic background were reared as juveniles either naturally in river or artificially hatchery (sea ranched), depriving them experience, then allowed to grow maturity ocean. At maturity, competitive abilities these fish compared four experiments quantifying success. Although levels aggressive behavior similar,...
The aim of the present study was to test possible habitat and food segregation between two charr morphs in Vangsvatnet Lake. population consists one pale phenotype with parr marks along flanks poorly developed spawning coloration (dwarf charr), another silvery nonbreeding condition bright red colors (normal charr). habitus indicated that they were adapted different niches during growth season. analyses distribution showed there marked summer, when dwarf dwelled deep-benthic normal roamed...
1. Density‐dependent factors appeared important for the survival of juvenile Atlantic salmon in River Imsa whilst density‐independent were more older fish at sea. In fresh water, density dependence was indicated by a stock−recruitment relationship with increasing loss‐rates from eggs to smolts and adults as egg increased. 73% explained variation density. At sea, independence lack significant between smolt densities. 2. The initial best described an asymptotic ‘Cushing’ type plateau densities...
(1) The chief objective was to compare life-history characteristics of sea-run migrating brown trout, Salmo trutta L., in a latitudinal gradient from 58 70?N Norway order reveal biogeographic trends characters. (2) annual length increment trout during the second year fresh water significantly, negatively correlated with latitude (r2=0-520), and positively river temperature (days) (r2 = 0700), growth season (number days t > 4 ?C, r2 0-549). first after smolting (r2= 0339), sea 0309). (3) Mean...
Summary Experimental data for maximum growth and food consumption of Atlantic Salmon ( Salmo salar L.) parr from five Norwegian rivers situated between 59 70°N were analysed modelled. The feeding models also applied to groups growing at rates below the maximum. fitted Ratkowsky model, originally developed bacterial growth. varied significantly among populations but variation appeared unrelated thermal conditions in river population origins. No correlation was found limits growth, optima or...
In 2005 a large outbreak of verotoxin-producing Escherichia coli (VTEC) occurred in Sweden. Cases were interviewed and cohort case–control studies conducted. Microbiological investigations performed using polymerase chain reaction (PCR) to detect the Shiga-like toxin (Stx) genes followed by cultivation pulsed-field gel electrophoresis. A total 135 cases recorded, including 11 hemolytic uremic syndrome. The epidemiological implicated lettuce as most likely source outbreak, with an OR 13.0 (CI...
Summary Catches of Atlantic salmon Salmo salar L. decreased in the 1980s and 1990s over its entire area North smolts were often released for stock enhancement. However, there are questions about their survival performance relative to fully wild fish. This paper reports on sea growth River Imsa from 1981 1999 as 1‐ 2‐year‐old hatchery smolts. Survival was significantly higher than Hatchery had lower survival, captured more coastal freshwaters, grew slowly attained maturity younger...
Energetic expenditure during spawning of male and female 1 ‐sea‐winter Atlantic salmon, Salmo salar L., was measured. Before spawning, the somatic energy content per unit weight did not differ between sexes. The testes offat 0.24, carbohydrate 8.89, water 1.21 ash 1.61 times as high that ovaries. Just prior to mean gonadosomatic index (GSI; wet weight, %) in males 4.36 females 20.26, expressed ratios (kJ, 4.47 27.75, respectively. During loss soma higher (35.57%) than (25.00%). This a result...