Data/hora: 08/06/2024 12:50:58

Provedor de dados: | 5
País: | France
Título: | Evaluating uncertainty in measurements of fish shoal aggregate backscattering cross-section caused by small shoal size relative to beam width
Autores: | Diner, Noel.
Data: | 2007-06
Ano: | 2007
Palavras-chave: | Shoal dimension; Shoal energy; Single beam echosounder; Acoustic measurements; Accuracy; Bias.
Resumo: | The aggregate backscattering cross-section, sag, is the sum of backscattering cross-sections of all fish in a shoal. It is a basic acoustical parameter used for shoal description and biomass estimation. Simulations were undertaken for evaluating the impact of horizontal dimension, density, depth and beam width on measurements of sag for shoals with constant abundance. The important factor determining measurement bias is the ratio of shoal size expressed as along cross-section length relative to along ship beam width at mean shoal depth. The results show that 10 log10(sag) is underestimated by about 8 dB for a 5 m long shoal located at 200 m depth if detected by a 7? beam. A formula for correcting sag estimates for shoal sizes bigger than 1.3 times the beam width is proposed. The negative measurement bias can also be reduced by using transducers with narrower beam widths.
Tipo: | Text
Idioma: | Inglês

Identificador:

http://archimer.ifremer.fr/doc/2007/publication-2583.pdf

DOI:10.1051/alr:2007022

Editor: | EDP Sciences
Relação: | http://archimer.ifremer.fr/doc/00000/2583/
Formato: | application/pdf
Fonte: | Aquatic Living Resources (0990-7440) (EDP Sciences), 2007-06 , Vol. 20 , N. 2 , P. 117–121
Fonte: | EDP Sciences, IFREMER, IRD 2007