An immediate problem for one fifth of humanity LandScan data (Bright et al. 2012) reveal that, worldwide, 1.36 billion people now live within 100 km of a tropical coastline-that is, almost one fth of the global population live on a narrow strip that is just 7% of the available land. These people occupy 9 megacities (10 million inhabitants or larger), but also live in numerous much smaller settlements. The average population density (145 people/km2) of this strip is twice that of inland populations, with coastal populations growing more rapidly (Sale et al. in press). Most of these people live in developing countries and many depend on their immediate coastal waters for much of their animal protein food, other resources, and their livelihoods. Only the wealthy are sufciently well connected to global markets that they do not depend directly on their local coastal waters. Coastal sheries provide both food and livelihoods for millions of poor people along these tropical coasts (Donner and Potere 2007).