Data/hora: 07/06/2024 04:40:10

Provedor de dados: | 5
País: | France
Título: | Association between bluefin tuna schools and oceanic features in the western Mediterranean
Autores: | Royer, Francois; Fromentin, Jean-marc; Gaspar, P.
Data: | 2004
Ano: | 2004
Palavras-chave: | Thunnus thynnus; Gulf of Lions; Point process analysis; Front detection; Sea surface temperature; Ocean colour; Aggregation.
Resumo: | We present an analysis of the distribution of bluefin tuna Thunnus thynnus schools spotted during aerial surveys in the Gulf of Lions, in relation to oceanographic features. Bio-optical and thermal properties of the sea surface derived from high-resolution sensors (AVHRR and SeaWiFS) were studied on a daily basis, and an edge-detection technique was applied to detect frontal zones. Geostatistics and point-process analyses were used to evaluate the role of the environment in structuring the spatial pattern of bluefin tuna (BFT). The distribution of schools spotted was strongly non-stationary both in space and time; this is believed to be an effect of the survey design (transect sampling) and the influence of transient oceanographic structures (surface fronts and eddies). The empirical variograms indicated a spatial range of the BFT schools at around 40 km, with substantial daily variability. Ripley's K statistic, as well as autocorrelation plots, revealed that the fish schools were clustered over a wider range of scales (from 10 to 80 km), indicating more spatial structure than would be expected from a random process. Finally, BFT school distributions appeared well determined by the oceanic features, except at very small scales (&lt;10 km), where over-aggregation occurred, and at the largest scales of our study (&gt;40 km), where over-spreading was detected. Dynamical ecological processes, such as foraging, are likely to induce this complex spatial pattern. Possible reasons for the association of tuna with fronts are presented.
Tipo: | Text
Idioma: | Inglês

Identificador:

http://archimer.ifremer.fr/doc/00000/10786/7585.pdf

DOI:10.3354/meps269249

Editor: | Inter-research
Relação: | http://archimer.ifremer.fr/doc/00000/10786/
Formato: | application/pdf
Fonte: | Marine Ecology Progress Series (0171-8630) (Inter-research), 2004 , Vol. 269 , P. 249-263