I hadn’t seen this article posted elsewhere. This seems to be the right place.

As Gonzaga University’s athletic teams compete nationally in various sports, the “Bulldogs” or “Zags” are recognized as its mascot and nickname. Gonzaga has not always used these terms. In its early athletic years, Gonzaga teams were unofficially called “the Blue and the White,” also the “Jesuits.” The 1911 football team was filled with thirty Irish Catholic boys so the newspaper referred to them as the “Fighting Irish.” Despite current campus folklore, there appears to be no connection with the name and trying to be like Notre Dame.