Yellowfin tuna probably first came to the attention of sport fishermen when they appeared on the tuna grounds of Catalina Island, California, only a few years after pioneering fishermen invented the sport, targeting the Pacific bluefin tuna. These tuna were of the same species caught by commercial fishermen in Japan and the western Pacific, but the reason for their appearance was not known at the time. Later, warmer water species such as yellowfin tuna, dorado and striped marlin were found to enter southern California waters in seasons having favorable ocean conditions, particularly during the El Niño phenomenon, which brings warmer water up North America's western coast.