-Initiatives for the sustainable development of aquaculture have so far focused on the production of codes of conduct, of best management practices, of standards etc., most of which have been developed by international organisations, the industrial sector and non governmental organisations. They were, to a large extent, produced using a "top down" process and inspired by models from intensive industrial shrimp and sea fish farming (mainly salmon). However, most of global aquaculture production comes from small-and medium-sized farms, essentially in Asia which contributes 92% of the total world aquaculture production volume. The objective of this article is to define the contours of systemic typologies that are able to express the sustainability conditions of aquaculture systems. The proposed approach builds on surveys of aquaculture systems which differ in terms of their biogeographical nature (temperate/tropical and north/south countries) or their farming techniques and their governance systems. This work is a prerequisite to any attempt at an individualised and comparative evaluation of specific aquaculture systems from either global or territorial viewpoints. In order to go beyond the cleavage of a typology based on the differentiation between developed and developing countries, three typologies were produced. These typologies allow for discriminatory variables to be identified such as for example the marketing methods or the pace of innovation: a structural typology, a functional typology and a systemic typology. Finally, the representations of aquaculture activity and of its sustainability that producers have of the 4 different types that emerge from the systemic typology were recorded and analyzed. 187-198 (2010) ont largement été produits selon un processus de type « top down » et principalement inspirés par les modèles issus de l'aquaculture industrielle intensive de crevettes et de poissons marins (saumon principalement). Cependant, l'essentiel de la production de l'aquaculture mondiale provient d'exploitations de petite et moyenne taille, en Asie principalement qui contribue pour 92 % au volume total de la production aquacole mondiale. Cette étude vise précisément à définir les contours de typologies globales aptes à rendre compte des conditions de durabilité des systèmes piscicoles. La démarche proposée s'appuie sur des enquêtes réalisées sur des systèmes de production différenciés tant sur les plans de la biogéographie (pays tempérés et tropicaux, du nord et du sud) que des techniques d'élevage mises en oeuvre et des modes de gouvernance de ces systèmes. Ce travail constitue le préalable à toute tentative d'évaluation à la fois individualisée et comparative de la durabilité de systèmes aquacoles spécifiques tant sur les plans systémique que territorial. Afin de dépasser le clivage d'une typologie basée sur la différenciation entre pays développés et en développement, trois typologies ont été produites. Elles permettent l'identification de variables discriminantes telles que par exemple l...

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Nile tilapia Oreochromis niloticus, initial age 12 days, were given an unrestricted (NR) or restricted (R) ration over 93 days which resulted in fish of very different sizes although the body condition factor (K) and the viscero-somatic index (I V ) remained almost unchanged. In a second stage (64 days) each group (NR & R) was divided into three subgroups that were subjected to 0 (NR0, R0), 15 (NR15, R15) and 30 (NR30, R30) days of food restriction, respectively. The impact of the different treatments on the somatic growth during the second stage of the experiment had an effect, with a highly significant difference between the mean .. masses (M T ) in the different subgroups (NR0=115·0 26·6 g; NR15=94·8 24·9 g; NR30=56·3 28 g; R0=76·4 20·1 g; R15=72·1 17·6 g; R30=43·6 17·2 g). Similarly, K and I V decreased. Irrespective of the initial feeding condition, the width of the otolith microincrements started to decrease at the end of the first or second day of restricted feeding. In the subgroups given a restricted food ration for 30 days (NR30 and R30), this decrease reached a plateau at about day 30, which was maintained even when the restriction had ended. This slowed growth did not lead to any marked halt in microincrement formation, since there were no significant differences (ANOVA; P>0·05) in the numbers of increments counted in the various subgroups. The results show that in 153 day old fish, a period of severe food restriction, even if prolonged (15 to 30 days), had no influence on the timing of the laying down of microincrements but only affected their growth.

Performances de reproduction du poisson chat endogène du CamerounClarias jaensis (Boulenger, 1909) en milieu contrôlé