Blar i Havforskningsinstituttet på emneord "acoustics"
Viser treff 21-40 av 308
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Acoustic and Bottom Trawl Surveys; How Much Information Do They Provide for Assessing the Northeast Arctic Cod Stock?
(ICES CM documents, Working paper, 1999)Acoustic and bottom trawl surveys of the Northeast Arctic cod stock provide fishery independent estimates of trends in abundance and population characteristics. Given the recent uncertainties in the catch based assessment ... -
Acoustic backscatter from zooplankton and fish explored through an optimized model framework
(ICES CM Documents;2004/R:39, Working paper, 2004)The purpose of this work has been to test complementary methods in order to classify marine organisms, with particularly attention to zooplankton and fish. Algorithms to separate fish and zooplankton have been developed ... -
Acoustic estimates of abundance of 0-group gadoids in the northern North Sea in July 1985
(ICES CM Documents;1986/G:28, Working paper, 1986)This paper presents the results from a joint survey with two research vessels in July 1985. Total estimates of abundance (N x 10-9 ), were: Norway pout 56, haddock 52, whiting 66 and cod 4. Comparisons are made with a ... -
Acoustic estimates of saithe in the North Sea in 1984 and 1985
(ICES CM Documents;1985/G:14, Working paper, 1985)This paper describes the results from a joint cruise in July 1984 with two vessels, and the results from two cruises in February - March 1985. In July the saithe were standing well above the bottom, but the saithe were ... -
Acoustic estimates of saithe in the North Sea in 1985 and 1986
(ICES CM Documents;1986/G:49, Working paper, 1986)This paper describes the results from a joint cruise in July 1985 with two vessels, and the results from one cruise in February 1986. The acoustic estimates agree fairly well with the estimates made by the North Sea ... -
Acoustic estimates of spawning cod off Lofoten and Møre in 1985
(ICES CM Documents;1985/G:66, Working paper, 1985)The annual surveys on the spawning stock of North-east Arctic cod were carried out in the Lofoten and Møre areas in March- April 1985. These surveys were undertaken to estimate the size and age structure of the spawning ... -
Acoustic extinction in dense herring layers, measured from a bottom-mounted transducer
(ICES CM documents, Working paper, 2006)Herring is often found in dense aggregations or schools, and acoustic shadowing is thus a problem in acoustic survey estimates. Knowledge of the attenuated echo intensity in herring aggregations is essential for correcting ... -
Acoustic investigation of fish behaviour apropos avoidance reaction
(ICES CM Documents;1981/B:21, Working paper, 1981) -
Acoustic investigations of size and distribution of the Barents Sea capelin stock 1972-1997
(Fisken og havet, Research report, 1998)The abundance and geographical distribution of the Barents Sea capelin stock have been monitored using acoustic methods since 1972. Today, 26 years later, it is one of the few stocks, within the ICES area, for which an ... -
Acoustic measurements of schooling herring. Estimation of school biomass and target strength
(ICES CM Documents;1988/B:26, Working paper, 1988)The connections between reflected echo energy and dimensions of fatty herring schools were studied by a combination of multibeam sonar and a calibrated echo integration unit. A relation between the area and the biomass ... -
Acoustic observations of jellyfish in the Namibian Benguela
(Journal article; Peer reviewed, 2001-01-26)Multi-frequency acoustic data (18, 38 and 120 kHz) were collected in conjunction with pelagic trawl sampling for gelatinous macrozooplankton during a cruise to the Namibian Benguela in September 1999. Sampling focused ... -
Acoustic portrait of herring in Vestfjord, january 1996, with geostatistical analysis
(ICES CM Documents;1996/H:31, Working paper, 1996)In January 1996 the stock of Norwegian spring-spawning herring (Clupea harengus) was acoustically surveyed in the wintering area. Both immature and mature fish were present. Because of the comparative lateness of the ... -
Acoustic properties of Salpa thompsoni.
(ICES CM documents;2009 / I:01, Working paper, 2009)Salps are common members of the world oceans planktonic community (Madin, et.al., 2006). In the southern ocean, both krill (Euphausia superba) and salps (Salpa thompsoni) can occur in dense aggregations (Loeb et al, 2009, ... -
Acoustic resonance determination of the rigidity modulus
(Others, 2001) -
Acoustic sampling volume
(Journal article; Peer reviewed, 1991)Knowledge of the acoustic sampling volume is necessary in many quantitative applications of acoustics. In general, the sampling volume is not merely a characteristic of the transmitting and receiving transducers, but also ... -
Acoustic sampling volume
(Others, 1989) -
Acoustic sampling volume versus equivalent beam angle
(ICES CM Documents;1988/B:5, Working paper, 1988)Irnprovements in target strength measurement have shown the equivalent beam angle (EBA) to be a worrisome source of error in echo integrator surveys. The reason is that the EBA is generally defined as a purely physical ... -
Acoustic scattering models of zooplankton
(Others, 1991)