Marchal Emile auteur aut IRD Josse Erwan auteur aut IRD Lebourges Anne auteur aut IRD text bookSection eng text/pdf reformatted digital access Predators seek congregated rather than scattered prey, and school themselves most of the time. In order to study the relationship between predators and preys, one needs to identify them. Classical methods of investigation, such as the use of different kinds of net (plankton, midwater trawl) with a regular sampling grid, often fail to succeed in catching them, due to their very heterogeneous distribution. In contrast, acoustics allows us to "see" and to study them, thanks to the very good transmission of sound in the water. A good example of the way acoustics could be used to study predator-prey relationships is provided by a tuna fishery in the Equatorial Atlantic which exploits a seasonal tuna concentration. It was assumed that tuna find here abundant food, supported by the very high percentage of a mesopelagic fish, Vinciguerria nimbaria, found in their stomach contents. However, this fish is known as a dial migrator, diving to deep waters during the daytime, where tuna could not catch them since they are view-feeders. Acoustic detection has proven that, in this case, this small fish could stay in the surface layers, aggregating in small schools at the thermocline level. In addition, acoustic tagging has shown that tuna were staying most of the time at this particular level. Finally, acoustic estimation of the packing density and the volume of these schools allows us to assume their actual role in the daily feeding of tuna. (Résumé d'auteur) specialized POISSON MARIN THON PREDATEUR RELATION PREDATEUR PROIE ETHOLOGIE ABONDANCE EVALUATION PROSPECTION ACOUSTIQUE 036MILMAR02 Petit Didier ed. edt IRD Cotel Pascal ed. edt IRD Nugroho D. ed. edt IRD 253-264 Luxembourg (LUX) Union Européenne Jakarta (IDN) CRIFI Paris ORSTOM 1997 AKUSTIKAN : Seminar, 2., Bandungan (IDN), 1996/05/27-29 https://www.documentation.ird.fr/hor/fdi:010017258 979-8186-64-8 [F A010017245] https://www.documentation.ird.fr/hor/fdi:010017258 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_7/carton01/010017258.pdf IRD - Base Horizon / Pleins textes 1999-03-03 2018-06-15 fdi:010017258 fre