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| Registros recuperados: 12 | |
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| Diner, Noel. |
| Models of simulated schools have been used to determine the intrinsic variability in echotraces due to beam pattern effect. This work concerns only morphometric and energetic parameters that can be extracted from echotraces. It appears that dST, the difference between school density and processing threshold is a key parameter, which directly influences the concerned detection angles. Relations, taking into account dST but also, Nbi, the relative school length image compared to the beam width, have been settled for the calculation of length and density corrections. In most cases, corrected values are obtained with errors less than respectively 5% for length and 0.5 dB for density (reverberation index), provided that the Nb-i value is 1.5 or more. When Nb-i... |
| Tipo: Text |
Palavras-chave: Banc de poissons; Détection de poissons; Acoustique; Fish schools; Fish detection; Acoustic. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-546.pdf |
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| Duhamel, Erwan; Biseau, Alain; Masse, Jacques; Villalobos, Hector. |
| The french fishery of anchovy is divided in two groups defined by gears : purse seine and pelagic trawl. The average length of these vessels is about 20m. This fleet is very opportunistic : all trawlers are using several trawls during the year, to catch sometimes bass, tuna, hake, or scampi, and purse seine are mainly fishing sardine. Each year, the main anchovy catches are provided by pair trawlers. Purse seiners operate often in coastal areas (<10 nautical miles); trawlers may operate until 50 nautical miles offshore but are banned inside the three miles coastal zone. The pair trawlers may operate from Basque country to western Channel according to fish availability. Purse seiners usually stay around their home harbour. |
| Tipo: Text |
Palavras-chave: Pelagic trawl; Purse seine; Anchovy; Bay of Biscay; Acoustic; Survey; ICES; PELGAS; Chalut pelagic; Bolinche; Anchois; Golfe de Gascogne; Acoustique; Campagne oceanographique; CIEM; PELGAS. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/acte-2296.pdf |
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| Samb, Birame; Petitgas, Pierre. |
| This study presents an application of the geostatistical one-dimensional (1D) transitive method for estimating the precision of acoustic pelagic abundance estimates in Senegal. In applying the method, the major problem encountered was how to take into account the temporal variability in the computation of the estimation variance. In acoustic surveys, echointegration is performed continuously along the ship's sailing track. For a survey design made of parallel transects, each transect can thus be considered as a sampling unit. By summing the density values along the transects to obtain biomass values per transect, the 2D estimation is simply reduced to a 1D estimation procedure. If the transects are equidistant, the geostatistical transitive method applied... |
| Tipo: Text |
Palavras-chave: Céostatistique; Variance; Acoustique; Abondance; Geostatistics; Variance; Acoustics; Abundance. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00188/29883/28348.pdf |
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| Registros recuperados: 12 | |
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