Since the 1800s, Peruvian fisherman noticed that their harvest completely failed every few years. This periodic event was associated with unusually warm waters off the coast of Peru.  These warm waters resulted from a shutdown of the upwelling circulation normally found along the equator. Since upwelling supplies nutrients to the surface waters, this resulted in mass starvation of plant and animal life in the eastern equatorial Pacific. Since the periodic warming almost always occurred around December, the fisherman named it El Niño, in reference to the Christ child.