The Benguela is one of four major current systems which exist at the eastern boundaries of the world oceans, and the oceanography of the region is in many respects similar to that of the Humboldt Current off Peru and Chile, the California Current off the west coast of the U.S.A. and the Canary Current off north-west Africa. These eastern boundary currents are characterized by upwelling along the coast of cold nutrient-rich water, and are important centres of plankton production which support a global reservoir of biodiversity and biomass of fish such as sardine (pilchard), anchovy and horse-mackerel and also sea birds and marine mammals.