The tragedy of the commons largely accounts for the declining condition of the world’s coral reefs, as in most areas of the world there is little to prevent over-harvesting and habitat destruction. Coral bleaching caused by global warming is also a problem. We might wonder why a large reef fish is worth more alive on the reef than served up on a plate in an expensive hotel: older fish lay disproportionately more eggs, so helping to increase reef biomass. 1 Reef fish also perform various ecological services, helping to maintain the ecosystem of a reef by eating algae and seaweed and preventing the corals from being over-grown. Can coral reefs be managed to better health? The device of the marine park discussed in this chapter is useful; the “classic” example is Australia’s Great Barrier Reef Marine Park. Even “traditional” social organizations can be used to reduce over-harvesting: in Fiji a Chieftain exercised the right to manage reef fish stocks, withdrew commercial fishing licenses, established no-take zones and used scientific knowledge of fish breeding habits and life cycles to set closed seasons. The results were impressive – labor productivity quickly doubled with the same quantity of fish being caught in half the time. Scientific evidence suggests that biomass inside no-take zones doubles in three to five years, and that this also benefits nearby areas. 2