Biologie et pêche traditionnelle des crevettes pénéides dans l'embouchure d'un fleuve en milieur semi-aride (sud-ouest de Madagascar)

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Éditeur(s) Gauthier-Villars
Identifiant documentaire 9-20828
Identifiant OAI oai:archimer.ifremer.fr:20828
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Auteur(s): Laroche, Jean,Benoely, ,Siaviri, A
Mots clés Pêche Estuaire Dynamique population Croissance Taille corporelle Cycle évolutif Zone semi aride Madagascar Penaeus japonicus Penaeus monodon Penaeus indicus Metapenaeus monoceros Rivière Onilahy Afrique Milieu saumâtre Macrura Decapoda Crustacea Arthropoda Invertebrata Fishing Estuaries Population dynamics Growth Body size Life history Semi arid zone Malagasy Republic Penaeus japonicus Penaeus monodon Penaeus indicus Africa Brackish water environment Macrura Decapoda Crustacea Arthropoda Invertebrata
Date de publication 01/01/1995
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Source Oceanologica Acta (0399-1784) (Gauthier-Villars), 1995 , Vol. 18 , N. 6 , P. 659-670
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Description
Traditional fishing using beach seines was studied over a period of one year at the mouth of the Onilahy river. The catches/efforts were recorded on a daily basis, biological sampling and the measurement of hydrological parameters being carried out twice a month. The moderate variations of salinity and temperature (14 < salinity < 35; 25 degrees C < temperature < 30 degrees C) which were observed in the estuary can be explained by the semiarid climate of the area. Four species of penaeid shrimps are to be found on the Onilahy: Metapenaeus monoceros, Panaeus indicus, Penaeus monodon and Penaeus japonicus, which were mainly caught at the subadult/adult stage with a Carapace length between 10 and 50 mm. The presence of these important sizes at the mouth of the river, associated with the fact that no mature female shrimps were observed in the catches, means that part of the population tends to extend its stay in the estuary. Growth parameters were estimated for M. monoceros and P. indicus, and the growth in the estuary appears to be faster than that observed at sea, especially for P. indicus. In contrast with what is observed in wet tropical areas, the decline in salinity is limited in semiarid climates and is thus not a major factor in the emigration of the shrimps towards the open sea. On the other hand, there is a rather precise link between emigration towards the open sea and falling temperature: important sizes disappear from the river mouth during the transition between autumn and winter. In the estuary of the Onilahy, a temporal partitioning of resources for the four species of penaeid, leading to a reduction of interspecific competition, can be underscored. The traditional fishing yield in the estuary was estimated at 220 metric tons of shrimps per annum, with a catch per unit effort of 15 to 22 kg/seine/trip.
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Biologie et pêche traditionnelle des crevettes pénéides dans l'embouchure d'un fleuve en milieur semi-aride (sud-ouest de Madagascar)

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