Nutrition-sensitive trade in island food systems: Zanzibar’s aquatic food trade as a lever for regional nutrient supply

Abstract Growing calls for food systems transformation invoke an urgent need to enhance health and nutrition outcomes while operating within sustainable planetary boundaries. Central to these calls are nutrition-sensitive food systems, value chains, and agriculture concepts, which collectively emphasize how nutrition or dietary outcomes can be incorporated into food systems to tackle underlying determinants of nutrition outcomes. These concepts, however, mainly focus on domestic systems and give limited attention to how regional and international trade redistributes nutrient-rich foods across borders. This gap is significant as trade reshapes diets through cross-border food flows, generating trade-offs between exporting and importing populations, creating spatial and seasonal redistribution of foods, and creating potential policy tensions between livelihoods and domestic nutrition. We empirically examine nutrition-sensitive trade within aquatic food systems, which are an ideal system because they are nutrient-dense, heavily traded, and their processed forms, such as dried fish, are important for inland and cross-border distribution. Using in-depth interviews ( n = 51) with actors across the value chain and key informants ( n = 10), this study examined trade in the dried dagaa ( Rastrineobola argentea ) fishery in Zanzibar to address two research questions relevant for nutrition-sensitive trade. We find that the dried dagaa fishery provides affordable protein and micronutrients to Zanzibar and at least six other countries, especially the Democratic Republic of Congo, which has high proportions of nutritionally vulnerable populations, with trade flows shaped by institutional, social, economic, and environmental factors. Furthermore, trade flows are dynamic, responding to seasonal and longer-term changes that reconfigure the availability of dagaa to local and non-local populations. We leverage these findings, and the questions they generate, to generate a research agenda to support policies and interventions promoting nutrition-sensitive trade, particularly among low- and middle-income countries, including island regions, to strengthen nutritional security at the local and regional scale.