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dc.contributor.authorNortvedt, Ragnar
dc.date.accessioned2012-07-03T09:27:24Z
dc.date.available2012-07-03T09:27:24Z
dc.date.issued1986
dc.identifier.citationThis report is not to be cited without prior reference to the authorno_NO
dc.identifier.urihttp://hdl.handle.net/11250/104163
dc.description.abstractAtlantic salmon (Salmo salar) and rainbow trout (S. gairdneri) eggs were incubated in plexi-glass aquariums. After hatching, alevins were kept in darkness, two groups of each species without substrate, two groups in gravel and two groups in Astroturf artificial substrate. Every sixth day after hatching, individual swimming height above the bottom were monitored with a video recording system. The use of infrared light made it possible to observe the positions in the water column in darkness. Mean swimming height in a coordinate system and percentage occurrence in specific heights above the bottom were used as measures on emergence from the bottom. Emergence was more conspicuous among the rainbow trout alevins (196 - 226 day degrees) than Atlantic salmon alevins (335 - 400 day degrees). After emergence, the rainbow trout alevins swam close to the water surface, and 50 % of them became photopositive on day 39 (269 day degrees). The Atlantic salmon stayed closer to the bottom after emergence, and they became heedless to light at this stage. This reflect different evolutionary strategies. Neither substrates nor feeding made influence on overall timing of emergence.no_NO
dc.language.isoengno_NO
dc.publisherICESno_NO
dc.relation.ispartofseriesICES CM Documents;1986/F:26
dc.subjectsalmonidsno_NO
dc.subjectlaksefiskerno_NO
dc.subjectjuvenile productionno_NO
dc.subjectyngelproduksjonno_NO
dc.subjectgrowthno_NO
dc.subjectvekstno_NO
dc.titleThe timing of emergence of Atlantic salmon and rainbow trout, incubated on different substratesno_NO
dc.typeWorking paperno_NO
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921no_NO
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Aquaculture: 922no_NO
dc.source.pagenumber34 s.no_NO


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