Quick Definition
The wind-driven rise of cold, nutrient-rich water from depth to the surface, creating highly productive fishing grounds.
📖 Full Definition
Upwelling occurs when surface winds blow water away from a coastline or equatorial belt, and cold, nutrient-rich water from 200–300 m depth rises to replace it. The nutrients (nitrate, phosphate, silicate) fuel phytoplankton blooms, supporting food chains that sustain some of the world's most productive fisheries. Major upwelling systems include the California Current, Humboldt Current, Benguela Current, and Canary Current. El Niño events suppress upwelling in the eastern Pacific with catastrophic impacts on fisheries.
💡 Examples & Context
The Humboldt Current upwelling off Peru and Chile supports the world's largest single-species fishery — the Peruvian anchoveta (Engraulis ringens).