Blar i ICES CM documents authored by IMR scientists (1949-2011) på emneord "akustikk"
Viser treff 201-216 av 216
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Spheres for calibrating an eleven-frequency acoustic measurement system
(ICES CM Documents;1989/B:3, Working paper, 1989)Calibration of a single resonant transducer by standard sphere is a simple matter. How does one calibrate an array composed of eleven different resonant transducers spanning the frequency range from 27 to 710 kHz? A ... -
Studying the relationship between spatial fish distributions and trawl catches
(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 ... -
Summary of methods for measuring fish target strength
(ICES CM Documents;1988/B:4, Working paper, 1988)Methods for measuring fish target strength are intercompared. The consistency of results obtained on the same or related species by different methods is noted. -
Survey design and analysis procedures: a comprehensive review of good practice
(ICES CM documents, Working paper, 1991)This paper provides a major review of acoustic survey and-data analysis procedures, it has been prepared as a result of discussions in the FAST working group of ICES. A review of published literature is combined with an ... -
Sustainable yield estimates of the Barents sea capelig stock
(ICES CM Documents;1982/H:45, Working paper, 1982)The Barents Sea capelin suffer mass mortality after spawning. A model is developed to calculate the biomass of springspawners using previous autumn acoustic survey estimates of the total stock as input data. It is assumed ... -
Target strength measurements and c-values determinations of live Skagerrak herring and cod
(ICES CM Documents;1981/B:12, Working paper, 1981) -
Test experiments of target strength of herring by comparing density indices obtained by acoustic method and purse seine catches
(ICES CM Documents;1994/B:17, Working paper, 1994)The spawning stock of the Norwegian spring spawning herring has been assessed by acoustic methods using the target strength TS = 20 logL - 71.9 dB (L = mean length of fish) Comparable estimates of fish density were ... -
Testing various geostatistical models to combine bottom trawl catches and acoustic data
(ICES CM Documents;2004/R:28, Working paper, 2004)The aim of the CATEFA project is to combine information on demersal fish stock abundance from acoustic and bottom trawl surveys. While acoustic data are collected continuously while the research ship is underway, it is ... -
The equivalent beam angle and its effective value when applying an integrator threshold
(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 ... -
The significance of fish behaviour in the evaluation of hydroacoustic survey data
(ICES CM Documents;1981/B:22, Working paper, 1981) -
Use of acoustics in studies of fish reaction to imposed stimuli
(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
(ICES CM documents, Working paper, 1991) -
Vertical distribution of cod, haddock and redfish; Impact on bottom trawl and acoustic surveys in the Barents Sea
(ICES CM Documents;1997/Y:16, Working paper, 1997)At a selected location in the Barents Sea acoustic observations, bottom- and pelagic trawl catch data were collected over a 10 day period. A large proportion of the fish were in the acoustic dead zone during the sampling ... -
Vessel heave, and index for air bubble attenuation corrections
(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 ... -
When acoustics is not enough – towards a measurement of sandeel availability
(ICES CM documents;2009/I:16, Working paper, 2009)Experimental surveys in the peak feeding season of sandeel (April-May) show that the abundance and geographical distribution of schooling lesser sandeels (Ammodytes marinus) can be acoustically measured, but the density ... -
Wideband beam pattern
(ICES CM Documents;1989/B:2, Working paper, 1989)Transducer directivity is important in the basic acoustic surveying methods of echo counting and integration. In quantifying the directivity, the beam pattern is often computed assuming ideal single-frequency operation. ...