Blar i Articles på emneord "acoustics"
Viser treff 21-39 av 39
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Hydroacoustic performance of fishery survey instruments
(Others, 2001) -
Importance of the swimbladder in acoustic scattering by fish: A comparison of gadoid and mackerel target strengths
(Journal article; Peer reviewed, 1980)Previous determinations of the swimbladder contribution to the fish backscattering cross section have been hindered by ignorance of the acoustic boundary conditions at the swimbladder wall. The present study circumvents ... -
Influence of Different Factors on Abundance Estimates Obtained from Simultaneous Sonar and Echo Sounder Recordings
(Journal article; Peer reviewed, 2011-12-28)Use of horizontal guided sonar in addition to vertical echo sounder may improve biomass estimation of pelagic fish schooling near the surface. But proportions of horizontal guided sonar to vertical echo integration estimates ... -
Lateral-aspect target strength measurements of in situ herring (Clupea harengus)
(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 ... -
Linearity of fisheries acoustics, with addition theorems
(Journal article; Peer reviewed, 1983)An experiment to verify the basic linearity of fisheries acoustics is described. Herring (Clupea harengus L.) was the subject fish. Acoustic measurements consisted of the echo energy from aggregations of encaged but otherwise ... -
Maintaining precision calibrations with optimal copper spheres
(Journal article; Peer reviewed, 1983)Effects of variations in quantities influencing the backscattering cross sections of solid elastic spheres are studied through a particular case. This is that of the 60-mm-diam copper sphere, which is being used worldwide ... -
Observations of cod reaction to trawling noise
(Working paper, 1988-04)Observations made from a stationary echo sounder, passed by a trawling vessel, clearly demonstrate the flight reaction of cod as a response to the noise from the vessel. Horizontal dispersal and downward swimming has been ... -
Observing individual fish behavior in fish aggregations: Tracking in dense fish aggregations using a split-beam echosounder
(Journal article; Peer reviewed, 2007)Acoustic instruments are important tools for observing the behavior of aquatic organisms. This paper presents a simple but efficient method for improving the tracking of closely spaced targets using a split-beam echosounder. ... -
Observing the behavioral response of herring exposed to mid-frequency sonar signals. (A)
(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 ... -
Ocean Acoustic Waveguide Remote Sensing (OAWRS) of marine ecosystems
(Journal article; Peer reviewed, 2009-12-03)Ocean Acoustic Waveguide Remote Sensing (OAWRS) has recently been shown to be capable of instantaneously imaging and continuously monitoring fish populations over continental shelf-scale areas, covering thousands of km2. ... -
Probing the deep: Acoustic characterization of the Mid-Atlantic Ridge ecosystem
(Journal article; Peer reviewed, 2006) -
Rather-high-frequency sound scattering by swimbladdered fish
(Journal article; Peer reviewed, 1985)A new model describes acoustic scattering by swimbladdered fish of lengths from at least 8 to 36 wavelengths. It represents a fish by an ideal pressure-release surface having the exact size and shape as the swimbladder. ... -
Toward a Global Ocean Ecosystem Mid-trophic Automatic Acoustic Sampler (MAAS)
(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 the acoustic estimation of jellyfish abundance
(Journal article; Peer reviewed, 2005-06-23)Acoustic target strengths (TSs) of the 2 most common large medusae, Chrysaora hysoscella and Aequorea aequorea, in the northern Benguela (off Namibia) have previously been estimated (at 18, 38 and 120 kHz) from acoustic ... -
Wide-Band Response of the Parametric Acoustic Array
(Others, 1973)