Pelagic fish abundance from Semarang (Central Java) to South China Sea in April 1993

1997

Partie d'ouvrage

Petit Didier, Nugroho D., Potier Michel

Petit Didier (ed.), Cotel Pascal (ed.), Nugroho D. (ed.), Proceedings of acoustics seminar AKUSTIKAN 2

Luxembourg (LUX) ; Jakarta (IDN) ; Paris : Union Européenne ; CRIFI ; ORSTOM, 1997, p. 159-170 ISBN 979-8186-64-8

AKUSTIKAN : Seminar, 2., Bandungan (IDN), 1996/05/27-29

An acoustic survey, from Semarang towards the South China Sea, allows the haline situation and the distribution of abundance in pelagic fishes at the end of the wet season to be described. At that moment, the fleet of Javanese seiners operates in the south-west of the Natuna Islands, in depths of 50 meters. The analysis of haline vertical profiles shows the presence of three zones : the Java Sea with vertical gradients due to the coastal desalinization, the Karimata Strait with isohaline water at 33.5% and the South China Sea with deep waters at 34%. The last sector where the fleet was operating, was three times richer than the Javanese waters at that time. Without direct correlation with that, the zonation of the abundance (scattered or aggregated fishes) follows the zonation of salinity. The water of the strait is poorer, and the water of the Java Sea is richer while the desalinization is stronger. It seems that the richness of water is particularly related to the bathymetry by the presence of an semipelagic fauna when the bottom exceeds 30 meters. This semipelagic fauna commutes twice migration towards the surface during the night, a behaviour which is more accentuated in this fishing zone than in the Java Sea. In the Karimata Strait, where the depth is less than 30 meters, the pelagic and benthic faunas are dominant. In the Java Sea, a great aggregation of larva and juveniles has been detected particularly in the South of Belitung Island, that confirms the role of the basin in the reproduction of pelagic species. At that period of the year, it is the slopes of the basin which seem to be richer. These populations, thus, avoid the strong coastal desalinization and also its deeper part. All these observations do not seem to confirm the theory of Hardenberg, which assumes the existence of a migration between the South China Sea and the Java Sea. (Résumé d'auteur)

Stocks [040PECHE03]

RESSOURCES HALIEUTIQUES ; POISSON MARIN ; ESPECE PELAGIQUE ; SALINITE ; DENSITE DE POPULATION ; VARIATION SPATIALE ; REPARTITION VERTICALE ; RYTHME NYCTHEMERAL ; PROSPECTION ACOUSTIQUE ; ABONDANCE ; BANC

INDONESIE

Fonds IRD [F A010017245]

fdi:010017255