Le développement de l'aquaculture saumâtre dans l'Aire Pacifique Evolution des paysages, dynamiques socio-économiques et impacts environnementaux dans deux territoires au Pérou et aux Philippines

Abstract : My focus is brackish pond aquaculture in tropical regions and adopts an interdisciplinary approach combining a range of methods used in geography, sociology, environmental science, economic and history. Based on two case studies in the Philippines (Pampanga) and Peru (Tumbes), the goal of this thesis was to analyze the development of aquaculture with an emphasis on the initial causes of aquaculture, its history, its spatial development, and on its socioeconomic impacts at a range of space and time scales. The methodology associates satellite image processing with fieldwork. Several pond mapping methods based on a combination of multispectral classification techniques and mathematical morphology were tested and compared. Using an object-oriented approach, most ponds could successfully be plotted across the study areas. This automated routine subsequently made it possible to detect and quantify aquaculture-related land use changes since the 1970s. Field investigation methods involved questionnaires, interviews, harvesting of second-hand data, direct observation, and a participation in daily activities of various stakeholders. Finally, I crafted a multi-agent model based on empirical data collected in the Pampanga delta with the aim of exploring the influence of a range of environmental and social parameters on landscape evolution. In Peru, the development of aquaculture goes back to the 1970s whereas in the Philippines it started much earlier. Based on time-sliced map sequences my work shows that since the 1980s a significant proportion of the pond extensions in the Pampanga delta occurred at the expense of ca. 11,000 ha of paddy cropland. By contrast, land use changes in Tumbes were less extensive and have mainly involved encroachment on natural vegetation. I also provide a detailed characterization of the present day farming systems, highlighting the origins and intensity levels of capital and labour. Through an evaluation of the economic performance of aquaculture production in the Philippines I was able to quantify average daily farm revenue, which appears sufficiently high to at least partly explain the sustained commitment to the activity in spite of low yields. The regional impacts of aquaculture-related activities on the delta were dealt with on a range of scales, including at individual and household levels. In Peru, I focused on labour migrations and employment, describing the average profile of these migrants and the role of farms in the initiation and perpetuation of labour flows. Local employment generated by aquaculture was also estimated between the years 1980 and 2006 and was found to exceed 2500 full-time jobs despite fluctuations over the study period. In the Philippines, the concept of livelihoods provided a conceptual framework for analyzing the forms of capital enjoyed by the different categories of local stakeholders that draw benefits from aquaculture, whether directly or indirectly. I worked out the various livelihood strategies at the household scale while also featuring the unique workings of the pond gleaning community. Among the impacts of aquaculture on the fabric of local communities, the emergence of social conflict, the development of new infrastructures and the emergence of an aquaculture industry are the most prominent, with also evidence of unequal impacts on local development. My multi-agent-based model, CHANOS, finally made it possible to explore and measure the impacts of aquaculture on landscape through the construction of nine scenarios. These depend on various biophysical processes that follow either cyclical, linear or non linear changes and involved three contrasting farmer behaviour patterns (rational, collective-minded, with limited rationality).
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Submitted on : Wednesday, January 19, 2011 - 6:33:13 PM
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François Mialhe. Le développement de l'aquaculture saumâtre dans l'Aire Pacifique Evolution des paysages, dynamiques socio-économiques et impacts environnementaux dans deux territoires au Pérou et aux Philippines. Géographie. Université Paris-Diderot - Paris VII, 2010. Français. ⟨tel-00557715⟩

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