Fig. 3. Evolution of the ratio of shrimp ponds to mangrove swamp and the ecological footprint threshold. The ecological footprint line (Rees and Wackernagel 1994) represents an estimate of the productive land and water area required to supply the resources that a human activity demands, as well as to absorb the wastes that it produces. The line is thus a sustainability indicator. It is drawn here at a ratio of 1:2 (1 ha of shrimp pond requires 2 ha of mangrove swamp), using references to shrimp aquaculture in Asia and Colombia (Kautsky et al. 2000).