Browsing Published in cooperation with others by Subject "acoustics"
Now showing items 61-80 of 221
-
Experiences in making acoustic measurements in a mesocosm with Calanus finmarchius
(ICES CM Documents;1997/FF:11, Working paper, 1997)In connection with a larger study of the effects of nutrification and turbulence on primary and secondary production, acoustic measurements have been made in the water volume defined by floating, vertically oriented, ... -
Extinction cross section of herring: New measurements and speculation
(ICES CM Documents;1994/(B+D+G+H):2, Working paper, 1994)Acoustic abundance estimation of dense, vertically extended aggregations of fish requires knowledge of the extinction cross section. An established method based on a comparison of the area backscattering coefficients ... -
Field intercalibrations of echo integrator systems
(ICES CM Documents;1978/B:25, Working paper, 1978)The paper reviews intercalibrations of echo integrators carried out in 1975 - 1977 where Norwegian research vessels have participated. Analog and digital integrator performance is compared, and methods to make integrator ... -
Fish behaviour during sampling as observed from free floating buoys - application for bottom trawl survey assessment
(ICES CM documents, Working paper, 1999)Varying fish distribution and behaviour during bottom trawl surveys has long been considered important for the reliability of survey abundance estimates. Size and species dependent behaviour may bias the estimates and ... -
Geostatistical analysis of acoustic survey data on 0-group herring in a fjord
(ICES CM Documents;1992/D:10, Working paper, 1992)An essentially pure aggregation of 0-group herring in Altafjord in northern Norway was acoustically surveyed on each of the first three days of December 1991. Measurements were made at 38 kHz during each survey and at ... -
How many trawl hauls, and how many fish from each haul are needed to obtain a given precision in the age structure estimate for Norwegian spring spawning herring? A bootstrap approach
(ICES CM documents, Working paper, 2006)The Norwegian spring spawning herring is assessed each year from acoustic surveys. The age structure in the stock is estimated from trawl samples. Typically, about 10 trawl samples are taken per survey, and 100 fish from ... -
How to correct fish density estimates for extinction
(ICES CM Documents;1990/B:24, Working paper, 1990)There have been many experimental studies on acoustic shadowing, but once the effect is quantified, how is the compensation to be effected? This work shows how, through postprocessing of stored time series, containing ... -
Hull mounted, protruding transducer for improving echo integration in bad weather
(ICES CM Documents;1990/B:31, Working paper, 1990)A 38 kHz split beam survey transducer has been mounted on the tip of a 4 m vertical protrusile stabilizing keel of the United States NOAA fishery research vessel R/V Miller Freeman. Air blocking problems, generally ... -
Hydroacoustic detection of food waste - a method to estimate maximum food intake of fish populations in sea cages
(ICES CM Documents;1990/F:7, Working paper, 1990)A linear relationship between echo energy and amount of salmon dry food was established. Measurements were carried out both for food batches (5-400 gram) and single pellets. For a certain amount of food, the echo energy ... -
ICES coordinated acoustic survey of ICES divisions IIIa, IVa, IVb AND Via (North) 2002 Results and long term trends
(ICES CM documents, Working paper, 2003)Six surveys were carried out during late June and July covering most of the continental shelf north of 54oN in the North Sea and to the west of Scotland to a northern limit of 62oN. The eastern edge of the survey area ... -
ICES coordinated acoustic survey of ICES divisions IIIa, IVa, IVb and VIa (North) 2003 Results
(ICES CM Documents;2004/R:32, Working paper, 2004)Six surveys were carried out during late June and July covering most of the continental shelf north of 52°N in the North Sea and to the west of Scotland to a northern limit of 62°N. The eastern edge of the survey area was ... -
Impact of herring spawning behaviour on acoustic abundance estimates
(ICES CM documents, Working paper, 2001)Spawning dynamics of Norwegian spring spawning herring was studied in south western Norway 29 March to 3 April 2000 using hydroacoustics. The horizontal distribution of the spawning layers shifted in a south-easterly ... -
Improved calibration of hydroacoustic equipment with copper spheres
(ICES CM Documents;1981/B:20, Working paper, 1981) -
In situ of Cape horse mackerel (Trachurus capensis)
(ICES CM Documents;1999/J:4, Working paper, 1999)The acoustical target strength (TS) of Cape horse mackerel (Trachurus capensis) was measured in situ at 38 kHz using a submersible split beam transducer in combination with a SIMRAD EK 500 echosounder. The transducer ... -
The influence of fish behaviour on acoustic abundance estimates during the spawning season in Norwegian spring-spawning herring
(ICES CM documents, Working paper, 2001) -
Initial collateral measurements of some properties of Calanus finmarchicus
(ICES CM Documents;1996/L:21, Working paper, 1996)In general, acoustic quantification of zooplankton such as Calanus finmarchicus requires the use of models, among other reasons, to aid in the interpretations of data collected on animals whose scattering properties change ... -
Inter-calibration of participating vessels in the ICES coordinated surveys of North Sea herring
(ICES CM Documents;1998/OPEN:23, Working paper, 1998)Summary: Three pairwise acoustic inter-calibrations of the performance of EK500 scientific echosounders were carried out in July 1997. The first inter-calibration was carried out at about 57 40'N by OE by GO Sars and ... -
Intercalibration of acoustic systems onboard R/V "Johan Hjort" and R/V "Pinro"
(ICES CM Documents;1992/B:17, Working paper, 1992)Inter-ship calibration is a comparison between integrator output of two or more ships sailing over the same fish aggregations. Although it is a relative measurement, it is highly desireable whenever research vessels ... -
International acoustic survey on blue whiting in the Norwegian Sea during summer 1986
(ICES CM Documents;1986/H:55, Working paper, 1986)The fifth ICES-coordinated acoustic survey on blue whiting in the Norwegian Sea and adjacent waters was conducted from the end of July to the beginning of September 1986. All together eight research vessels from USSR, ... -
International Acoustic Survey on Blue Whiting in the Norwegian Sea, August 1984.
(ICES CM Documents;1984/H:67, Working paper, 1984)Six research vessels from the five nations, USSR, Norway, Faroe Islands, Iceland and GDR participated in the third ICES-coordinated acoustic survey on blue whiting in the Norwegian Sea and adjacent waters. By use of ...