One of the main challenges for improving the sustainability of value chain is that of understanding its function and mapping them, which implies the creation of a typology of actors and activities, to be used as a basis for analyses, generalisations and extrapolation. This work maps (i.e. thoroughly describes) the fisheries-based value chains in two contrasted countries in which these value chains are important activities for a large percentage of the population: The Gambia, where marine fisheries dominate, and Mali, where inland fisheries dominate. We explored, quantitatively and qualitatively, the geographical distribution, organisation, technical performance and exploited ecosystems associated with these value chains, as a means to facilitate their sustainability assessment. We applied an approach (Value Chain Analysis for Development) developed by policy makers and implemented by scientists within time constrains, in scarce data contexts, to monitor how development actions contribute to sustainable development goals. The challenges of mapping fisheries value chain are described and recommendations for improving both value chain assessments in general and the case study value chains in particular are proposed.