Blar i ICES CM documents authored by IMR scientists (1949-2011) på forfatter "Godø, Olav Rune"

Viser treff 21-40 av 58

    • Distribution of bioluminescence and plankton in a deep Norwegian fjord measured using an ISIT camera and the Digital Underwater Video Profiler 

      Bailey, David M.; Picheral, Marc; Jamieson, Alan J.; Godø, Olav Rune; Bagley, Philip M.; Gorsky, Gabriel (ICES CM documents;2007/F:02, Working paper, 2007)
      Bioluminescence and plankton profiles were obtained using a downward-looking ISIT low-light camera and the Underwater Video Profiler system in Sognefjord, Norway. The profiling systems were lowered by CTD wire and recorded ...

    • Diurnal variation in acoustic densities: why do we se less in the dark? 

      Hjellvik, Vidar; Godø, Olav Rune; Tjøstheim, Dag (ICES CM Documents;2004/R:33, Working paper, 2004)
      Introduction: In the Barents Sea, the echo abundance of demersal fish is about 50% higher at day than at night. Three possible reasons are: • Fish hide in the bottom dead zone at night. • Fish target strength changes due ...

    • Diurnal variation in bottom trawl survey catches: does it pay to adjust? 

      Hjellvik, Vidar; Godø, Olav Rune; Tjøstheim, Dag (ICES CM Documents;2001/Q:11, Working paper, 2001)
      We have studied the diurnal bias of bottom trawl survey catches with the purpose of adjusting for it and thereby improving the accuracy of abundance estimates. The correction term is estimated with uncertainty, and thus ...

    • Diurnal variation in frequency response of gadoids in the Barents Sea 

      Godø, Olav Rune; Hjellvik, Vidar; Tjøstheim, Dag (ICES CM documents, Working paper, 2006)
      Earlier studies have demonstrated substantial diurnal variation in acoustic abundance of fish. Both the level and the uncertainty of abundance estimates from surveys carried out around the clock are affected. It has been ...

    • Estimates of stock size of Northeast Arctic cod and haddock from survey data 1986/1987 

      Godø, Olav Rune; Hylen, Arvid; Jacobsen, Jan Arge; Jakobsen, Tore; Mehl, Sigbjørn; Nedreaas, Kjell Harald; Sunnanå, Knut (ICES CM documents, Working paper, 1987)
      Combined acoustic and bottom trawl survey for cod and haddock were carried out in the Svalbard area in autumn 1986 and in the Barents Sea during the winter 1987. An acoustic survey for spwaning cod was carried out in March ...

    • Fish behaviour during sampling as observed from free floating buoys - application for bottom trawl survey assessment 

      Godø, Olav Rune; Somerton, David; Totland, Atle (ICES CM documents, Working paper, 1999)
      Varying fish distribution and behaviour during bottom trawl surveys has long been considered important for the reliability of survey abundance estimates. Size and species dependent behaviour may bias the estimates and ...

    • Fisheries-induced evolution in cod 

      Heino, Mikko; Godø, Olav Rune; Dieckmann, Ulf (ICES CM documents;2010/M:24, Working paper, 2010)
      Over the last eight decades, northeast Arctic cod has shown a marked change towards earlier maturation at smaller sizes. At the same time, harvesting shifted from primarily targeting mature cod in the spawning grounds to ...

    • Habitat selection and competition amongst 0-group gadidae off Mid-Norway 

      Godø, Olav Rune; Sunnanå, Knut; Gjøsæter, Jakob; Dragesund, Olav (Working paper, 1988)
      Juvenile gadids and other co-occurring fishes were collected during August in the years 1981 to 1983 at the Møre coast (Mid-Norway). The gears used were pelagic trawl, bottom trawl, Danish seine and beach seine. All species ...

    • Immigration and emigration of cod in the spawning areas of Lofoten and Møre 

      Godø, Olav Rune (ICES CM Documents;1984/G:48, Working paper, 1984)
      Abundance estimates of the spawning stock of north east Arctic cod have in recent years been given on the basis of acoustic surveys. Migration in and out of the surveyed areas during investigation has been considered as a ...

    • Incorporating experimentally derived estimates of survey trawl catchability into the stock assessment process 

      Somerton, David; Ianelli, Jim; Walsh, Stephen J.; Smith, Stephen; Godø, Olav Rune; Ramm, David (ICES CM Documents;1997/W:5, Working paper, 1997)
      During the course of the April, 1996, meeting of the Fishing Technology and Fish Behavior Working Group it became clear to many that the methodology for experimentally estimating the catchability of survey trawls might ...

    • Interaction and integration of observation and models – the EcoFish approach 

      Godø, Olav Rune; Hauge, Kjellrun Hiis; Hjøllo, Solfrid Sætre; Iversen, Svein A.; Kjesbu, Olav Sigurd; Nash, Richard D.M.; Svendsen, Einar (ICES CM documents;2007/R:14, Working paper, 2007)
      Ecosystem approach to fisheries management demand new scientific approaches and tools. The EcoFish project is a recently established project that pursues the challenges set by the new approach. It aims at supporting ...

    • Measuring the effect of changes in catchability on the variance of marine survey abundance indices 

      Pennington, Michael; Godø, Olav Rune (ICES CM Documents;1992/D:9, Working paper, 1992)
      The average catch per tow by a research vessel survey is often used as an index of abundance. An estimate of the variance of such indices that is based only on the between station variability in catch may underestimate ...

    • Migratory behaviour of reared Norwegian coastal cod and north east Arctic cod 

      Godø, Olav Rune; Totland, Atle (ICES CM Documents;1995/G:11, Working paper, 1995)
      This paper is based on experiments to test if differences in migratory behaviour of Norwegian coastal cod and north east Arctic cod is related to parental origin or, alternatively, is related to the environmental experienced ...

    • Minimalistic surveys clear the way for priorities in the ecosystem approach 

      Godø, Olav Rune; Hjellvik, Vidar; Tjøstheim, Dag; Korsbrekke, Knut (ICES CM documents;2009/I:20, Working paper, 2009)
      Standardized surveys are an integral part of most fish stock assessments. Ship time is expensive and new demands set by the ecosystem approach challenge present survey and sampling strategies with respect to coverage of ...

    • Modelling Diurnal Variation in Bottom Trawl Catches and Potential Application in Surveys 

      Hjellvik, Vidar; Godø, Olav Rune; Tjøstheim, Dag (ICES CM documents, Working paper, 1999)
      Diurnal variability in bottom trawl survey catches may influence the quality of the survey results when not taken properly into account. This is especia]!.y the case if diurnal effects vary substantiaIly from year to ...

    • Monitoring changes in abundance of gadoids with varying availability to surveys 

      Godø, Olav Rune; Wespestad, Vidar G. (ICES CM Documents;1991/G:76, Working paper, 1991)
      The use of scientific survey data for assessing abundance of commercially important fish stocks has become a managerial necessity in many regions. Errors and bias in estimates from such surveys may thus have great economic ...

    • Natural fish behaviour and catchability of groundfish 

      Godø, Olav Rune (ICES CM Documents;1994/G:14, Working paper, 1994)
      Imprecision in estimates of abundance and population parameters obtained from trawl surveys could be reduced if the sources of variability were understood and properly described. Fish behaviour in relation to sampling ...

    • Near-bottom sampling with bottom and pelagic trawls 

      Engås, Arill; Godø, Olav Rune (ICES CM Documents;1987/B:15, Working paper, 1987)
      The Institute of Marine Research, Bergen, has carried out combined bottom trawl and acoustic surveys for cod and haddock in the Barents Sea - Svalbard area since 1981. These investigations have demonstrated clearly that ...

    • NORFISK - an ecosystem simulation model for studies of the fish stocks off the coast of Norway 

      Bax, Nicholas J.; Sunnanå, Knut; Godø, Olav Rune; Dragesund, Olav (ICES CM Documents;1984/B:25, Working paper, 1984)
      A biomass based ecosystem simulation model has been fitted to a restricted area of the Norwegian coastal waters. The model uses a holistic ecosystem approach and data on biomasses and their interaction with each other ...

    • Observing behaviour of over-wintering Herring (Clupea harrengus L.) in Ofoten with Acoustic Current profiler 

      Patel, Ruben; Godø, Olav Rune; Lohrmann, Atle (ICES CM Documents;2003/Q:6, Working paper, 2003)
      In this paper we present results and interpretation of velocity and signal strength data collected with a ‘Continental’ Current Profiler on over-wintering herring in the Ofoten in the North of Norway. The instrument was ...