caa a22 4500 397551088 CHVBK 20180308164750.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0065 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0065 Diel variability of school structure with special reference to transition periods [Elektronische Daten] [P. Fréon, F. Gerlotto, M. Soria] Pelagic fishes generally disperse at dusk and aggregate in schools at dawn. The dynamics (duration, variation in school number, and characteristics) of these two behavioural processes have been studied during a 26 h survey in a small area of high fish abundance in the Catalan Sea (Spain). The dynamics of aggregation and dispersion were investigated using a dual-beam vertical echo-sounder (BioSonics) connected to a special school integrator software package (INES-MOVIES-B) which estimates school parameters in terms of size, geometry, and density. This study shows that, during the night, fish dispersion is limited and schools can still be observed. They are characterized by a highly skewed distribution of the cross-sectional area (many small schools plus a few medium and large schools), low values of packing density and biomass, and irregular shape, while during the day there are only a few schools which have a lower variability of the area, high values of packing density, and a more regular shape. The dynamics of schooling are different between dawn (fast aggregation) and dusk (slower dispersion). © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence acoustics nationallicence diel behaviour nationallicence Mediterranean Sea nationallicence Sardina pilchardus nationallicence school nationallicence Fréon P. ORSTOM, BP 5045, 34032 Montpellier, France aut Gerlotto F. ORSTOM, BP 5045, 34032 Montpellier, France aut Soria M. ORSTOM, BP 5045, 34032 Montpellier, France aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 459-464 1054-3139 53:2<459 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0065 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0065 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fréon P. ORSTOM, BP 5045, 34032 Montpellier, France aut NATIONALLICENCE 700 1- Gerlotto F. ORSTOM, BP 5045, 34032 Montpellier, France aut NATIONALLICENCE 700 1- Soria M. ORSTOM, BP 5045, 34032 Montpellier, France aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 459-464 1054-3139 53:2<459 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford