What should be the policy to meet urban food needs in developing countries and those in transition? This is a key question of the Food and Agriculture Organization of the United Nations (FAO), which was posed into the “FAO’s methodological and operational guide to study and understand Food Supply and Distribution Systems (FSDS) to cities in developing countries and countries in transition” in order to face the current overwhelming increase of urban population and the increasing urbanization pressures on food systems. Following some previous work in the field where it was argued that clarifying the various problems and structure behind Food Supply and Distribution Systems (FSDS) in urban environments is vital to assess policies that aim at meeting urban food needs, the purpose of this paper is to show that the methodological approach known as system dynamics modeling and simulation can lead, in terms of knowledge and/or theoretical contribution, to the unfolding of complexity in this area of research as well as bring into the analysis the relationships across a few goals of the Agenda 2030. As an additional result, we show how the developed model can be applied (case of the production of milk for consumption in the city of Bogota, Colombia) to analyze the dynamics of food supply and distribution systems in urban environments.

The Zapatosa marsh (ciénaga de la Zapatosa) is located in the Department of Cesar in Colombia. In 2018, the muddy complex of Zapatosa was declared a Ramsar wetland, for this reason, it is necessary to develop management strategies for the marsh that allow not only the conservation of the ecosystem. The objective of this work is to use System Dynamics as an evaluation tool for three possible management scenarios of artisanal fishing in the Zapatosa marsh. A qualitative causal diagram and a quantitative Stock and Flow diagrams were designed to describe the dynamics of fish and fishermen populations in the marsh. The initial model setting and parametrization derived from values gathered from different sources of information. The calibration of the model was carried out with reference data on total catch of kilograms of fish and population data from the Department of Cesar. The data obtained through the “Aquaculture and artisanal fisheries survey of the Department of El Cesar” in 2018 were reproduced in the model and then compared with 3 alternative management scenarios. Scenario 1 included strictly applying of the fishing stopover for the species Prochilodus magdalenae and for catfish (Pseudoplatystoma magdaleniatum, Pimelodus blochii y Sorubim cuspicaudus). Scenario 2 considered to apply the same prohibitions, but with a payment to fishermen for the care of the swamp at the time of prohibition. In Scenario 3 the fishermen under fishing stop will receive an income of a legal Colombian minimum monthly salary and will be engaged in practices of ecosystem services. Results showed that in some scenarios the economic situation of the fishermen is unable to meet the monthly family expenses in different periods of the year. On the other hand, there is greater economic stability and fish populations when adopting Scenario 3, but it is difficult to achieve in the short or medium term. Scenario 2 shows little recoveries in fish populations and a higher money availability to the local community than in Scenario 3, in certain months, presenting the best short-term management option. The presented model encourages further simulation scenarios of the Zapatosa Marsh.