For traditional island communities in the Nicobar archipelago, complete no-go areas are the most effective form of marine management

The ability of local communities to sustainably manage natural resource harvests in coral reefs ecosystemdepends heavily on the strength of traditional institutions. Coastal communities have evolved a suite ofrestrictive practices to control marine offtake and there is considerable recent evidence of their effec-tiveness in protecting and enhancing resource stocks. However, traditionally imposed restrictions canvary considerably in their complexity and in their functional effectiveness. The indigenous communitiesof the Nicobar Islands are dependent on marine resources for sustenance, managing them with a range oftraditionally imposed restrictions. These include limited entry to certain locations, closed seasons andareas, and restrictions on species, size-classes of fish and fishing methods. We tested the relativeeffectiveness of protection in areas managed under different traditional control regimes by comparingthe abundance and biomass of targeted fish groups in managed and unmanaged areas. Our resultsindicate that reef sites with the strictest form of restriction e essentially no-go areas e had significantlyhigher abundance and biomass values of most functional groups of fishes compared with partiallyprotected and control locations. In contrast, targeted food fish stocks did not differ from control locationsin partially protected sites managed with even complex forms of traditional management. Ensuring thattraditional harvest rules are complied is critical to the success of any management system, and our re-sults suggest that they can be most strictly enforced in traditional no-go areas. Our work highlights theimportance of critically evaluating the factors influencing traditional management systems to strengthentheir ability to protect these reefs from unsustainable overharvest.