Locally managed marine areas (LMMAs) are increasingly recognised as a key strategy for small-scale fisheries management across the Indo-Pacific. When effective, LMMAs can encourage responsible fishing, strengthen compliance and improve adaptive capacity, and may help to safeguard food security, address coastal poverty and increase resource sustainability. However, evidence that LMMAs can achieve long-term biological goals is limited. Here, we used a six-year dataset and a before-after-control-impact sampling design to assess the biological effectiveness of five community-managed no take zones (CMNTZs) situated within the Velondriake LMMA in southwest Madagascar. Linear mixed-effect models revealed that the difference in biomass between control and reserve sites increased over time. Significant differences in biomass between CMNTZs and controls were only evident from year two onwards, with 189% more total biomass in CMNTZs than fished control sites by year six. There was no effect of CMNTZs on the biomass of fish families preferentially targeted by the local fishery, limiting the long-term fisheries benefits of this reserve network unless individual CMNTZs are made larger to accommodate the home ranges of fishery targeted families. There were however, reserve effects preventing the decline of untargeted fish families and species richness.
Importantly, these CMNTZs delivered a conservation benefit that rivals government-run NTZs in the region, against a backdrop of severe biomass depletion, coastal poverty and human dependence on fishing – illustrating their suitability as a solution to marine resource depletion in developing tropical countries.