Using single-beam side-lobe observations of fish echoes for fish target strength and abundance estimation in shallow water

Citation
M. Moszynski et Jb. Hedgepeth, Using single-beam side-lobe observations of fish echoes for fish target strength and abundance estimation in shallow water, AQU LIV RES, 13(5), 2000, pp. 379-383
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences
Journal title
AQUATIC LIVING RESOURCES
ISSN journal
0990-7440 → ACNP
Volume
13
Issue
5
Year of publication
2000
Pages
379 - 383
Database
ISI
SICI code
0990-7440(200009/10)13:5<379:USSOOF>2.0.ZU;2-#
Abstract
Acoustic surveys for determining fish abundance in shallow water present ma ny challenges. One constraint to down-looking (or vertical) surveys is that the sampling volume is Limited due to the short range and typically narrow beams of acoustic transducers. By utilizing more of the acoustic beam, int o the side-lobes for example, the sampling volume may be increased. Althoug h the echo energy contribution from the side-lobes is usually small, these echoes may influence target strength estimation and echo counting, and by e xtension affect abundance estimation either directly or indirectly. With th e advent of wide dynamic range echosounders, it is possible to assess both small and large acoustic-size targets. In this case, it is possible to coll ect signals from large targets in the beam side-lobes, and therefore an alg orithm to use side-lobe data is proposed. The smoothed expectation Maximiza tion method (EMS) is used to estimate densities and target strength of fish from only main-lobe and main-lobe with side-lobe observations in simulatio n, and suggestions are made for real data from surveys. (C) 2000 Ifremer/CN RS/INRA/IRD/Cemagref/Editions scientifiques et medicales Elsevier SAS.