Paramo J. auteur aut IRD Bertrand Sophie auteur aut IRD Villalobos H. auteur aut IRD Gerlotto François auteur aut IRD text journalArticle eng text/pdf born digital access Fish school typology is usually based on vertical echosounding images. These images provide little objective information on school structure (internal characteristics) or morphology (external characteristics). This paper considers the possibility of using multibeam sonar for 3D recording of the external morphology and internal structure of schools, to enhance the identification of typological criteria. We used recordings of 668 schools obtained from three different regions (Senegal, 68; Venezuela, 343; Mexico, 257) on two different Clupeids (Venezuela and Senegal: Sardinella aurita; Mexico: Sardinops sagax). We extracted 26 parameters (4 geographical; 6 morphological; 16 structural) from each school in the data base, using geostatistics and 3D image-reconstruction software. The schools were very homogeneous in most of their characteristics, presenting unimodal distributions of most parameters. Structural variables presented a higher power of discrimination (significant differences among zones, species and positions in the water column) than morphological ones. Multivariate statistics (principal component analysis followed by mixed hierarchical classification) allowed the definition of four main classes of schools. The conclusion is that the structural data provided by multibeam sonar improves the possibility of obtaining a consistent typology. specialized fish school characteristics multibeam sonar school morphology school internal structure 040 84 2 171-179 2007 0165-7836 https://www.documentation.ird.fr/hor/fdi:010037946 10.1016/j.fishres.2006.10.023 0165-7836 [F B010037946] https://www.documentation.ird.fr/hor/fdi:010037946 https://www.documentation.ird.fr/intranet/publi/2007/06/010037946.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2007-06-28 2017-08-23 fdi:010037946 fre