• Behavioral responses of herring (Clupea harengus) to 1–2 and 6–7 kHz sonar signals and killer whale feeding sounds 

      Doksæter, Lise; Godø, Olav Rune; Handegard, Nils Olav; Kvadsheim, Petter H.; Lam, Frans-Peter A.; Donovan, Carl; Miller, Patrick J. O. (Journal article; Peer reviewed, 2009-01)
      Military antisubmarine sonars produce intense sounds within the hearing range of most clupeid fish. The behavioral reactions of overwintering herring (Clupea harengus) to sonar signals of two different frequency ranges ...
    • Estimating tail-beat frequency using split-beam echosounders 

      Handegard, Nils Olav; Pedersen, Geir; Brix, Ole (Journal article; Peer reviewed, 2009-02-04)
      Data from a standard split-beam echosounder are used to estimate tail-beat frequency within a dense herring (Clupea harengus L.) layer. The data were collected by lowering a horizontally projecting 38 kHz split-beam ...
    • Guidelines towards an integrated ocean observation system for ecosystems and biogeochemical cycles 

      Claustre, Hervé; Antoine, David; Boehme, Lars; Boss, Emmanuel; D`Ortenzio, Fabrizio; D`Andon, Odile Fanton; Guinet, Christophe; Gruber, Nicolas; Handegard, Nils Olav; Hood, Maria; Johnson, Ken; Körtzinger, Arne; Lampitt, Richard; LeTraon, Pierre-Yves; Lequéré, Corinne; Lewis, Marlon; Perry, Mary-Jane; Platt, Trevor; Roemmich, Dean; Testor, Pierre; Sathyendranth, Shubba; Send, Uwe; Yoder, Jim (Journal article; Peer reviewed, 2009)
      The observation of biogeochemical cycles and ecosystems has traditionally been based on ship-based platforms. The obvious consequence is that the measured properties have been dramatically undersampled. Recent technological ...
    • Lateral-aspect target strength measurements of in situ herring (Clupea harengus) 

      Pedersen, Geir; Handegard, Nils Olav; Ona, Egil (Journal article; Peer reviewed, 2009-07)
      Surveys of schooling herring with the new multi-beam sonar (Simrad MS70) pose new challenges when converting the echo energy to estimates of biomass. Since the sonar projects horizontally, data and models of lateral-aspect ...
    • 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 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 ...
    • 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 ...