The widespread use of pesticides for the agricultural activities has resulted in the contamination of numerous fresh water ecosystems and pesticides have been documented to be accumulated by fish. Extensive fish ponds were strongly connected with their surrounding watersheds. Thus this study concern the interactions between ponds and watershed management to have a best understand of the transfer processes be1Ween environmental and biological matrices. 5 sites were selected with 5 levels of agriculture intensification on their watersheds. To identify the influent factors on the transfer processes, the watershed and fish pond variables were studied. The samples of fish (2 species), sediments and water were realised. The identification of substances susceptible to penetrate into the fish pond systems has been conducted be1Ween 2003 and 200; The analyses for the envrronmell1al and biological matrices were conducted in order to realise a multi-residues approach. An analytical method based on liquid chromatography tandem mass spectrometry was developed for the determination of 13 pesticides. The extraction of analyses from fish and sediment represented a more complicated and delicate work. Preliminary steps of sample preparation, including the use of ultraturrax, the development of a Pressure Liquid Extraction (PLE) method and a single solid-phase extraction (SPE) were optimized. At last the effects of agricultural intensification on pesticide contamination in water sediment and fish were compared by simple parametric analyses (ANOVA) and data analyses. A Geographical Information System has been used to restitute the results at the parcel scale. The identification of pesticides have revealed a large spectrum of substances according to the levels of agricultural intensification. The chemical pressure which applies on the studied sites showed a variation in the pesticide concentrations for the 3 matrices. This study showed that the contaminations of the environmental and biological matrices were variables in quality and in quantity. Only the surveys with a multi-contaminants approach and also some spatio-temporal considerations were relevants to endeavour a best understand of the transfer process in aquatic systems.