 This strong upwelling brings nutrients from the subsurface layers of the ocean, thereby enhancing the fertility of the offshore waters.This results in strong plankton growth which in turn supports a more bountiful fishery in the region.In extreme circumstances during the winter, truly cold, dense, air occasionally flows from the Bay of Campeche in the Gulf of Mexico through the Chivela Pass into the Gulf of Tehuantepec on the Pacific side.