Browsing ICES CM documents authored by IMR scientists (1949-2011) by Subject "acoustics"
Now showing items 201-220 of 221
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Sound speed measeurments of Antarctic krill
(ICES CM Documents;1989/B:7, Working paper, 1989)The longitudinal sound speed in Euphausia superba has been measured by time of flight of an acoustic pulse through a suspension of krill in a T-shaped tube with nominal path length of 20 cm. Results are presented. -
Spatial and temporal overlap and trophic interactions between Atlantic Saithe (Pollachius virens) and Norwegian spring spawning herring (Clupea harengus) on herring spawning grounds
(ICES CM documents, Working paper, 2005)Atlantic saithe (Pollachius virens) and Norwegian spring-spawning herring (Clupea harengus) represent two of the most abundant and ecologically important fish species in the Northeast Atlantic. The two species co-occur ... -
Spatial density distributions of fish, a balance between environmental and physiological limitation
(ICES CM documents, Working paper, 2001)Data (trawl, acoustic, CTD) from four scientific survey series , i.e. along the Norwegian coast, in the North Sea, and in the Barents Sea summer and winter, are used to describe and discuss the spatial density distributions ... -
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) -
Using artificial neural networks to combine acoustic and trawl data in the Barents and North Seas
(ICES CM documents, Working paper, 2004)Groundfish have a wide and variable distribution making the use of trawling alone a highly inadequate sampling method. Trawl data provide species identification and numbers over a very small area and habitat type while ... -
Verified acoustic identification of Atlantic mackerel
(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 ... -
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 ...