Environmental impacts of farms integrating aquaculture and agriculture in Cameroon.
Résumé
In sub-Saharan Africa, fish constitutes the main source of animal protein for human consumption. Producing fish in ponds fertilized by manure could help to diversify family-scale agricultural production in this region. Life Cycle Assessment (LCA) could improve understanding of the contribution of fish-pond systems to regional sustainable development. The study analyzed four farms that integrated fish farming with other agricultural production, and in which fish ponds were fertilized either by pig manure and/or crop by-products, in two regions of the western highlands of Cameroon (5-7°N, 9-11°E), Alou and Fokoué. LCA was conducted using the CML2001 characterization method, adapted to aquaculture production, with one tonne of fresh fish at the farm gate as the functional unit and background data from the ecoinvent® database. Dynamics of nitrogen (N) and phosphorus (P) were evaluated using a nutrient mass-balance modeling approach, which showed that low quantities of N and P were assimilated by the fish in these systems. Eutrophication impact was higher for these Cameroonian farms than that of other aquaculture systems in the literature, mainly due to the pig manure and wheat bran used to supply nutrients. Water and nutrient management will need to be improved to increase efficiency of these fish farms.