Publications des scientifiques de l'IRD

Trygonis V., Georgakarakos S., Dagorn Laurent, Brehmer Patrice. (2016). Spatiotemporal distribution of fish schools around drifting fish aggregating devices. Fisheries Research, 177, p. 39-49. ISSN 0165-7836.

Titre du document
Spatiotemporal distribution of fish schools around drifting fish aggregating devices
Année de publication
2016
Type de document
Article référencé dans le Web of Science WOS:000372378600006
Auteurs
Trygonis V., Georgakarakos S., Dagorn Laurent, Brehmer Patrice
Source
Fisheries Research, 2016, 177, p. 39-49 ISSN 0165-7836
Omnidirectional sonar surveys were conducted in close proximity to drifting fish aggregating devices (FADs) offshore Seychelles, western Indian Ocean, to investigate the number, size, and distribution of FAD-associated fish schools. Echotrace detection techniques applied on the raw multibeam data enabled the extraction of empirical statistics regarding inter-school distances, and allowed the visualization of the temporal evolution of the pelagic aggregation on a FAD-centered coordinate system. The sonar recordings revealed the concurrent existence of multiple fish schools that were spatially clustered and exhibited low permanence in size and structure. Schools were predominantly detected within a radius of 500 m from the FADs, although 15% of detections occurred between 500 to 1500 m from the floating devices. Fish school biomass detected with the sonar was aggregated into a few, large schools during daytime, and dispersed into a larger number of small schools during nighttime. Compared to daytime observations, nighttime schools maintained smaller inter-school distances and were located closer to the drifting FADs. The study demonstrates that horizontal sonars are powerful tools for studying the spatiotemproral distribution of large pelagic schools in the vicinity of drifting FADs.
Plan de classement
Ressources halieutiques [040]
Localisation
Fonds IRD [F B010065929]
Identifiant IRD
fdi:010065929
Contact