Blar i Published in cooperation with others på forfatter "Ona, Egil"

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    • Repeated acoustic surveys on small herring in a fjord area 

      Ona, Egil; Røttingen, Ingolf (ICES CM Documents;1986/H:70, Working paper, 1986)
      This paper describes an acoustic survey on small herring in a fjord in Northern Norway which was carried out three times during the same night. The survey speed was 4 knots during two of the survey runs and once 8 ...

    • Seasonal variability in cod target strength 

      Ona, Egil (ICES CM documents, Working paper, 2006)
      The acoustic target strength of adult cod (Gadus morhua) was measured ex situ in a large, 4500 m3, experimental net pen at the IMR Austevoll aquaculture station in eight periods between November 1996 and May 1998. A ...

    • Some pitfalls of short-range standard-target calibration 

      Ona, Egil; Foote, Kenneth G.; Zhao, Xianyong; Svellingen, Ingvald (ICES CM Documents;1996/B:36, Working paper, 1996)
      Often it is necessary or desirable to perform a standard-target calibration at rather short range, for example, because of shallow water or interest in measuring animals at short range. A number of general range-dependent ...

    • The equivalent beam angle and its effective value when applying an integrator threshold 

      Ona, Egil (ICES CM Documents;1987/B:35, Working paper, 1987)
      In a noise-limited echo integration system, a threshold is applied in order to avoid the contribution from noise. As the signal-to-noise ratio decreases with range, the effective observation volume for small targets is ...

    • Tilt angle measurements on herring 

      Ona, Egil (ICES CM documents, Working paper, 1984)

    • Tilt angles of schooling penned saithe 

      Foote, Kenneth G.; Ona, Egil (ICES CM Documents;1985/B:26, Working paper, 1985)
      Saithe (Pollachius virens) of nearly uniform 32 cm length have been photographically observed during the daytime in an apparently free-swimming and schooling state in a pen of dimensions 90 m length, 10 m width, and 7 ...

    • Use of acoustics in studies of fish reaction to imposed stimuli 

      Ona, Egil; Beltestad, Arvid K. (ICES CM Documents;1985/B:44, Working paper, 1985)
      The general distribution pattern of fish in a large holding pen is described through the integrated echo intensity in six separate cells using transducers mounted below the pen. The reaction of fish to different stimuli, ...

    • Using acoustic surveys to improve the prediction of bottom trawl indices of abundance 

      Ona, Egil; Pennington, Michael; Vølstad, Jon Helge (ICES CM documents, Working paper, 1991)

    • Verified acoustic identification of Atlantic mackerel 

      Korneliussen, Rolf J.; Ona, Egil (ICES CM documents, Working paper, 2004)
      Calibrated, digitised data from simultaneously working multi-frequency echo sounders with nearly identical and overlapping acoustic beams have been used to generate new, synthetic echograms where only targets identified ...

    • Vessel heave, and index for air bubble attenuation corrections 

      Ona, Egil (ICES CM Documents;1991/B:37, Working paper, 1991)
      The possible use of vessel heave as a correction indicator for air bubble attenuation of acoustic signals from hull mounted transducers is investigated. Vessel heave was monitored along with the echo energy from the air ...