Assessing coral reef food system changes in southwestern Madagascar through traditional ecological knowledge

The diverse fisheries of coral reef ecosystems play an important role in human nutrition, particularly in rural coastal communities.Yet, coral reefs face threats such as overfishing, climate change, and pollution.Where long-term monitoring is absent, innovative methods must be used to understand trends in the health of coral reefs and their services.Traditional ecological knowledge (TEK), the knowledge indigenous people and generational residents carry about their relationship to their environments, can be used to supplement scientific data in understudied areas.This study used TEK to understand changes in the aquatic food system in the Bay of Ranobe, southwestern Madagascar.By collecting information on the perception of three dimensions of change: ecological abundance (i.e., population), fishers' catches, and household consumption of reef-associated resources through 97 household surveys across 3 communities, we assessed retrospective recall of decadal changes spanning 2012-2022.To better understand TEK heterogeneity, we evaluated the association between participants' demographic characteristics and their recall of change.Most marine resources we investigated were perceived to have declined in all dimensions.Compared to finfish, invertebrates such as spider conches (i.e., Lambis sp.) and Triton's snails (i.e., Charonia sp.) showed the smallest perceived declines across all dimensions, particularly in consumption.Our results highlighted TEK heterogeneity across demographic groups, with certain demographics (i.e., females and younger individuals) perceiving a lower decline in marine resource status, especially regarding perceived catch and ecological abundance.Demographic factors were associated with perceptions of decline in the abundance, catch, and consumption of some, but not all, resource groups.Our results suggest a major challenge to food security and livelihoods in the area because of declining stocks and potential community compositional shifts, and support the use of TEK from varied demographics to understand the impact of ecological change on fisheries and identify local conservation priorities.

Community-based conservation · coral reef fisheries · demographic differences in perception · food system transformation · household food security · livelihoods · southwestern Madagascar · traditional ecological knowledge · Coral and Marine Ecosystems Studies · Marine and coastal ecosystems · Marine and fisheries research