| Registro completo |
| Provedor de dados: |
ArchiMer
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| País: |
France
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| Título: |
Association between bluefin tuna schools and oceanic features in the western Mediterranean
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| Autores: |
Royer, Francois
Fromentin, Jean-marc
Gaspar, P
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| Data: |
2004
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| Ano: |
2004
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| Palavras-chave: |
Thunnus thynnus
Gulf of Lions
Point process analysis
Front detection
Sea surface temperature
Ocean colour
Aggregation
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| 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 (<10 km), where over-aggregation occurred, and at the largest scales of our study (>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.
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| Tipo: |
Text
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| Idioma: |
Inglês
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| Identificador: |
http://archimer.ifremer.fr/doc/00000/10786/7585.pdf
DOI:10.3354/meps269249
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| Editor: |
Inter-research
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| Relação: |
http://archimer.ifremer.fr/doc/00000/10786/
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| Formato: |
application/pdf
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| Fonte: |
Marine Ecology Progress Series (0171-8630) (Inter-research), 2004 , Vol. 269 , P. 249-263
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