Although oceans cover about 70% of the Earth's surface, most food is produced on land areas through agriculture and animal husbandry. This is because 90% of the ocean is unproductive. The productive areas are near shore, such as continental shelfs, upwellings, coral reefs, mangrove swamps (also known as mangal communities), and estuaries. The primary reason why these near shore areas are more productive than the open ocean is because of the supply of nutrients which are needed for plant (primarily phytoplankton) productivity, which fuels the food chain/web.

A worldwide plateau in harvesting of natural fish catch was reached in about 1989, so commercial and sport fisheries in the oceans cannot be increased unless something is changed. One possibility is to enhance production through fertilization of the water. Another, more practical, possibility is through aquaculture. As wild harvests decrease and per capita seafood consumption increases, aquaculture should have an...