Browsing ICES CM documents authored by IMR scientists (1949-2011) by Subject "acoustics"
Now showing items 81-100 of 221
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Investigations on blue whiting in the area west of the British Isles, spring 1994
(ICES CM Documents;1994/H:12, Working paper, 1994)From March 25 to April 15 the Norwegian R.V. "Johan Hjort" carried out acoustic surveying and biological and plankton sampling on the blue whiting population congregated for spawning along the shelf edge west of the ... -
Investigations on blue whiting in the area west of the British Isles, spring 1995
(ICES CM Documents;1995/H:7, Working paper, 1995)In March/April 1995 the fifth Norwegian-Russian joint acoustic survey on the blue whiting spawning stock was carried out. The shelf edge area to the west of The British Isles was covered by two vessels in a general ... -
Long-term movement patterns of coastal cod (Gadus morhua)
(ICES CM Documents;2001/L:18, Working paper, 2001)Movement patterns were studied by means of hydroacustic telemetry along the Norwegian Skagerrak coast. Ultrasonic transmitters was surgically implanted in 10 coastal cod, and released in the same area as they where caught. ... -
Mapping the migration pattern of schooling fish by use of multi-beam sonar during conventional acoustic surveys
(ICES CM Documents;1994/Mini:9, Working paper, 1994)Information on migration pattern and swimming behaviour of pelagic fish schools in the vicinity of steaming survey vessels has been collected by a multi-beam sonar system connected to an external device for data collection ... -
Measurements of Target stength and Spatial Orientation of Euphausiids (krill).
(ICES CM Documents;1981/B:l7, Working paper, 1981) -
Modelling herring target strength pressure dependence in the frequency domain
(ICES CM documents, Working paper, 2001)Improved understanding of the acoustic scattering properties of the fish is needed when trying to remove potential bias is acoustic abundance estimates. The paper address the problem of systematic pressure or depth dependency ... -
Monitoring fish communities at drifting FADs: an autonomous system for data collection in an ecosystems approach
(ICES CM documents;2009, Theme session I, Working paper, 2009)An increasing proportion of landings by tuna purse seine fishing vessels are taken around drifting Fish Aggregating Devices (FADs). Although these FADs and their use by the fishing industry to capture tropical tuna have ... -
More on the frequency dependence of target strength of mature herring
(ICES CM Documents;1993/B:30, Working paper, 1993)The hibernating stock of Norwegian spring-spawning herring has been acoustically surveyed in a fjord system in northern Norway in December 1992. The survey frequencies are 18, 38, 120, and 200 kHz. When the corresponding ... -
Norwegian acoustic survey of North East Arctic cod on the spawning grounds off Lofoten
(ICES CM Documents;1997/Y:18, Working paper, 1997)An acoustic survey of the spawning stock of North East Arctic Cod off Lofoten has been performed annually in March-April since 1982. The estimates for 1985-1997 have been recalculated and mean length and weight at age ... -
Observation of fish behaviour, density and distribution around a surveying vessel by means of a deployable echo sounder system
(ICES CM Documents;1999/J:9, Working paper, 1999)Detailed acoustic observations of fish behaviour, distribution and density in the trawl area are necessary in order to establish quantitative relationships between trawl samples and fish density. Acoustic observation ... -
Observing behaviour of over-wintering Herring (Clupea harrengus L.) in Ofoten with Acoustic Current profiler
(ICES CM Documents;2003/Q:6, Working paper, 2003)In this paper we present results and interpretation of velocity and signal strength data collected with a ‘Continental’ Current Profiler on over-wintering herring in the Ofoten in the North of Norway. The instrument was ... -
On the application of the echointegration method
(ICES CM documents;1983/B:19, Working paper, 1983)The echo integration method used by the Institute of Marine Research is described. The model which are used to convert acoustic abundance indices into fish densities using length and species dependant conversion factors, ... -
On the depth dependence of fish target strength
(ICES CM Documents;1997/FF:7, Working paper, 1997)Data on the depth dependence of the target strength of live kokanee (Oncorhynchus nerka), a physostome, at 50 kHz (Mukai, T., and Iida, K., ICES J. mar. Sci., 53: 245-248 (1996)) have been reexamined. In the cited study, ... -
On the frequency dependence of target strength of mature herring
(ICES CM Documents;1992/B:10, Working paper, 1992)Mature herring (Clupea harengus), hibernating in Ofotfjord in December 1991, was measured simultaneously at each of three frequencies: 18, 38, and 120 kHz. Measurements of the mean volume backscattering coefficient were ... -
Optimal acoustic beam pattern corrections for split beam transducers
(ICES CM Documents;1990/B:30, Working paper, 1990)Precise in situ target strength estimates of fish can only be made when the effect of the transducer directivity is totally removed from the recorded target amplitudes. By guiding a standard calibration target through ... -
PC-based echo integration system for fish behaviour studies
(ICES CM Documents;1988/B:35, Working paper, 1988)An echo integration system presenting the distribution and vertical and horizontal movements of fish in net pens, is described. The system can be configured to multiplex up to 16 transducers sequentially. The number of ... -
Performance of an acoustic sonde design
(ICES CM Documents;1994/L:30, Working paper, 1994)The potential of multi-frequency acoustic technology for quantifying fish and plankton is widely recognized. At a U.S. GLOBEC workshop in 1991, one of the considered problems was measuring macrozooplankton and micronekton. ... -
Pinging down the food web: multi-frequency acoustic discrimination of jellyfish and fish
(ICES CM Documents;2004/R:6, Working paper, 2004)Jellyfish are gaining increasing prominence in many pelagic marine ecosystems worldwide. It has been argued that jellyfish-dominated communities will be the end-point in ecosystems perturbed by high fishing effort, and ... -
Positive relationships between bottom trawl and acoustic data
(ICES CM documents, Working paper, 2004)Demersal fish stock biomass is usually estimated using commercial landings data, ‘tuned’ by various types of survey data, usually trawl. When collecting fish data by trawl it is only possible to take relatively small numbers ... -
Preliminary report of the Norwegian acoustic survey of blue whiting (March - April 1974)
(ICES CM Documents;1974/B:13, Working paper, 1974)