epidemiology of bacterial diseases in norwegian aquaculture--a description based on antibiotic prescription data for the ten-year period 1991 to norway, antibacterial drugs for use in farmed fishes have to be prescribed by a veterinarian. moreover, a national surveillance programme requires that copies of all prescriptions be sent to the directorate of fisheries. the prescriptions give information regarding fish farm and locality, weight and species of fish to be medicated, diagnosis, type and amount of drug prescribed, and date. these prescription data for the 10 yr period 1991 to 2000 have been recorded and systematised. a total of ...200312650244
fish status survey of nordic lakes: effects of acidification, eutrophication and stocking activity on present fish species composition.the status of fish populations in 3821 lakes in norway, sweden and finland was assessed in 1995-1997. the survey lakes were chosen by stratified random sampling from all (126 482) fennoscandian lakes > or = 0.04 km2. the water chemistry of the lakes was analyzed and information on fish status was obtained by a postal inquiry. fish population losses were most frequent in the most highly acidified region of southern norway and least common in eastern fennoscandia. according to the inquiry results, ...200312733793
selective predation on parasitized prey--a comparison between two helminth species with different life-history lake fjellfrøsvatn, northern norway, the larval helminths cyathocephalus truncatus and cystidicola farionis use gammarus lacustris as intermediate hosts and arctic charr (salvelinus alpinus) as final hosts. there was sampled 1,433 live g. lacustris from the lake and 1,964 g. lacustris from stomach contents of the charr. prevalence of infection were, respectively, 0.49% and 3.72% for c. truncatus, and 0.21% and 0.20% for c. farionis. usually, only 1 parasite was present in each host, and the 2 ...200111695412
new parasites and predators follow the introduction of two fish species to a subarctic lake: implications for food-web structure and functioning.introduced species can alter the topology of food webs. for instance, an introduction can aid the arrival of free-living consumers using the new species as a resource, while new parasites may also arrive with the introduced species. food-web responses to species additions can thus be far more complex than anticipated. in a subarctic pelagic food web with free-living and parasitic species, two fish species (arctic charr salvelinus alpinus and three-spined stickleback gasterosteus aculeatus) have ...201323053223
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