African waters have been contributing to the global supply of fish for years, with three of the four most productive marine ecosystems in the world near the continent. African countries' Exclusive Economic Zones (EEZs) contributed over 6 million metric tons of fish to the world's food supply, supporting food security and livelihood in the continent, while generating $15 billion to the African gross domestic product in 2011. Every sovereign state has an EEZ, an area of ocean adjacent to their shores in which they have special rights regarding the exploration and use of marine resources.