In October 2003, the North Pacific Marine Science Organization was asked by the United States government for scientific advice on the implications of the 1998 regime shift for North Pacific fisheries. Following the strong 1997-1998 El Niño, the climate of the North Pacific took a rapid and striking change, the persistence of which is suggestive of a regime shift. Previous regime shifts have had serious implications for marine ecosystems, and consequently for fish populations and the fishing industry.