Blar i Brage IMR på forfatter "Handegard, Nils Olav"

Viser treff 61-80 av 81

    • Observing the behavioral response of herring exposed to mid-frequency sonar signals. (A) 

      Handegard, Nils Olav; Doksæter, Lise; Godø, Olav Rune; Kvadsheim, Petter H. (Conference object, 2010-03)
      There is general concern on how mid-frequency military sonars might affect aquatic animals. Approaches used to investigate possible effects on Norwegian spring spawning herring (Clupea harengus) are presented. Experiments ...

    • The One Ocean Expedition: Science and Sailing for the Ocean We Want 

      Huse, Geir; Baussant, Thierry; Becker, Meike; Biuw, Martin; Bødtker, Gunhild; Cook, Jeremy; Gomiero, Alessio; Grøsvik, Bjørn Einar; Handegard, Nils Olav; Hestnes, Arne Johan; Hole, Lars Robert; Husson, Berengere; Jaccard, Pierre Franqois; Johannessen, Johnny Andre; Krolicka, Adriana; Lien, Vidar Surén; Lindemann, Christian; Olsen, Are; Renner, Angelika; Lid, Sjur Ringheim; Steen-Larsen, Hans Christian; Strand, Espen; Westgaard, Jon-Ivar; Pedersen, Geir (Rapport fra havforskningen;2023 - 34, Research report, 2023)
      The One Ocean Expedition (OOE) was a 20-month long circumnavigation of the globe by the Norwegian sail training vessel Statsraad Lehmkuhl, and a recognised part of the UN decade of Ocean Science for Sustainable Development. ...

    • PELFOSS (PELagic Fish Observation System Simulator) 

      Skogen, Morten D.; Handegard, Nils Olav; Holmin, Arne Johannes; Hjøllo, Solfrid Sætre; Mousing, Erik Askov; Utne, Kjell Rong; Vabø, Rune (Rapport fra havforskningen;30-2018, Research report, 2018)
      PELFOSS har utviklet en observasjonssystem-simulator for pelagisk fisk i Norskehavet. Simulatoren er en dataløype der romlig fordeling av fiskebestander fra en økosystemmodell er benyttet til å simulere ulike tokt. Disse ...

    • Quantitative processing of broadband data as implemented in a scientific split-beam echosounder 

      Andersen, Lars Nonboe; Chu, Dezhang; Handegard, Nils Olav; Heimvoll, Harald; Korneliussen, Rolf; Macaulay, Gavin; Ona, Egil; Patel, Ruben; Pedersen, Geir (Peer reviewed; Journal article, 2023)
      The use of quantitative broadband echosounders for biological studies and surveys can offer considerable advantages over narrowband echosounders. These include improved spectral-based target identification and significantly ...

    • The sampling volume of trawl and acoustics: estimating availability probabilities from observations of tracked individual fish 

      Handegard, Nils Olav; Tjøstheim, Dag (Journal article; Peer reviewed, 2009-03-10)
      The effective sampling volume of trawl and acoustics is an important parameter in fish abundance estimation surveys. This paper presents a method to compute the probability of a fish being available to the bottom trawl and ...

    • Semi-supervised target classification in multi-frequency echosounder data 

      Choi, Changkyu; Kampffmeyer, Michael; Handegard, Nils Olav; Salberg, Arnt Børre; Brautaset, Olav; Eikvil, Line; Jenssen, Robert (Peer reviewed; Journal article, 2021)
      Acoustic target classification in multi-frequency echosounder data is a major interest for the marine ecosystem and fishery management since it can potentially estimate the abundance or biomass of the species. A key problem ...

    • Silent research vessels are not quiet 

      Ona, Egil; Godø, Olav Rune; Handegard, Nils Olav; Hjellvik, Vidar; Patel, Ruben; Pedersen, Geir (Journal article; Peer reviewed, 2007)
      Behavior of herring Clupea harengus stimulated by two ocean-going research vessels; respectively designed with and without regard to radiated-noise-standards. Both vessels generate a reaction pattern, but, contrary to ...

    • Simulations of multi-beam sonar echos from schooling individual fish in a quiet environment 

      Holmin, Arne Johannes; Handegard, Nils Olav; Korneliussen, Rolf J.; Tjøstheim, Dag (Journal article; Peer reviewed, 2012-12)
      A model is developed and demonstrated for simulating echosounder and sonar observations of fish schools with specified shapes and composed of individuals having specified target strengths and behaviors. The model emulates ...

    • Smart Fisheries in Norway: Partnership between Science, Technology, and the Fishing Sector 

      Handegard, Nils Olav; Algrøy, Tonny; Eikvil, Line; Hammersland, Hege; Tenningen, Maria; Ona, Egil (Journal article, 2021)

    • Spawning Atlantic cod (Gadus morhua L.) exposed to noise from seismic airguns do not abandon their spawning site 

      McQueen, Kate; Meager, Justin James; Nyqvist, Daniel; Skjæraasen, Jon Egil; Olsen, Esben Moland; Karlsen, Ørjan; Kvadsheim, Petter Helgevold; Handegard, Nils Olav; Sivle, Lise Doksæter; Forland, Tonje Nesse (Peer reviewed; Journal article, 2022)
      Seismic airgun surveys may disturb and displace fish at large ranges. If such displacement causes fish to abandon spawning grounds, reproductive success could be impacted. To investigate whether airgun sound causes cod ...

    • StoX: An open source software for marine survey analyses 

      Johnsen, Espen; Totland, Atle; Skålevik, Åsmund; Holmin, Arne Johannes; Dingsør, Gjert Endre; Fuglebakk, Edvin; Handegard, Nils Olav (Journal article; Peer reviewed, 2019)
      Scientists across the globe conduct survey programs to monitor and characterize abundance, population structure, biodiversity and geographical distributions. To assess the state of marine fish and zooplankton, population ...

    • Studying the relationship between spatial fish distributions and trawl catches 

      Trenkel, Verena M.; Godø, Olav Rune; Handegard, Nils Olav; Patel, Ruben (ICES CM Documents;2004/R:26, Working paper, 2004)
      We propose an approach for studying the relationship between spatial fish distributions and the distribution of numbers in trawl catches. Individual spatial fish distributions are derived from acoustics data collected with ...

    • Survey report for CRIMAC SFI 2023 

      Handegard, Nils Olav; Allken, Vaneeda; Holmin, Arne Johannes; Johnsen, Espen; Korneliussen, Rolf; Pedersen, Geir; Skjefstad, Joakim; Rogge, Rabea Patricia; Samuelsen, Mikal Arntzen; Tenningen, Maria; Sivle, Lise Doksæter (Toktrapport;2024 - 7, Research report, 2024)
      This cruise report describes the objectives, methods, and preliminary results from the tasks carried out at the CRIMAC SFI survey. The survey was conducted on board RV G.O. Sars between November 15th (Tromsø) and November ...

    • Testing acoustic platforms and methodology for studying behaviour of demersal fish in a bottom trawl survey [19/9 - 10/10, 2005] 

      Godø, Olav Rune; Handegard, Nils Olav; Johansen, Geir Odd; Torkelsen, Terje; Totland, Atle; Pedersen, Ronald ([Toktrapport/Havforskningsinstituttet];Nr. 21 - 2005, Working paper, 2005)

    • The effective swept volume of a bottom trawl 

      Handegard, Nils Olav; Tjøstheim, Dag (ICES CM Documents;2004/R:7, Working paper, 2004)
      The reaction of individual fish towards an approaching trawling vessel has previously been measured using target-tracking methods. In this paper these measured velocities are fitted to a deterministic mean behaviour ...

    • Toward a Global Ocean Ecosystem Mid-trophic Automatic Acoustic Sampler (MAAS) 

      Handegard, Nils Olav; Demer, David A.; Kloser, Rudy; Lehodey, Patrick; Maury, Olivier; Simard, Yvard (Journal article; Peer reviewed, 2009-05-26)
      Despite their huge biomass and pivotal role, the mid-trophic levels of marine ecosystems are not generally subject to systematic monitoring. Data from such monitoring is crucial for parameterizing, validating, and constraining ...

    • Toward a Global Ocean Ecosystem Mid-trophic Automatic Acoustic Sampler (MAAS) 

      Handegard, Nils Olav; Demer, David A.; Kloser, Rudy; Lehodey, Patrick; Maury, Olivier; Simard, Yvard (Journal article; Peer reviewed, 2009-05-26)
      Despite their huge biomass and pivotal role, the mid-trophic levels of marine ecosystems are not generally subject to systematic monitoring. Data from such monitoring is crucial for parameterizing, validating, and constraining ...

    • Towards Operational Management Of Pelagic Ecosystems 

      Lehodey, Patrick; Senina, Inna; Calmettes, Beatriz; Royer, Francois; Gaspar, Philippe; Abécassis, Mélanie; Polovina, Jeffrey; Parker, Denise; Domokos, Réka; Hernandez, Olga; Dessert, Morgane; Kloser, Rudy; Young, Jock; Lutcavage, Molly; Handegard, Nils Olav; Hampton, John (ICES CM documents;2010/A:04, Working paper, 2010)
      Satellite data and operational ocean models provide the necessary inputs for ecosystem models of the lower to mid- and upper trophic levels. One key explanatory variable that is usually missing to understand the dynamics ...

    • Tracking individual fish from a moving platform using a split-beam transducer 

      Handegard, Nils Olav; Patel, Ruben; Hjellvik, Vidar (Journal article; Peer reviewed, 2005)
      Tracking of individual fish targets using a split-beam echosounder is a common method for investigating fish behavior. When mounted on a floating platform like a ship or a buoy, the transducer movement often complicates ...

    • Underwater sound measurements from fishing vessel "Brennholm" 

      Peña, Hector; Øvredal, Jan Tore; Totland, Bjørn; Handegard, Nils Olav (Working paper, 2011-08)
      A methodology for measuring underwater sound from free running vessels was implemented inside IMR, following American National Standard ANSI/ASA S12.64-2009 grade B. An array of 3 calibrated NEXUS hydrophones was mounted ...