The bishop submitted his resignation to Pope Francis upon turning 75, as required by the Code of Canon Law.
He will be succeeded by Bishop Marcel Damphousse, who is currently bishop of Alexandria-Cornwall in eastern Ontario.
Plouffe turned 75 on Oct. 19. The Ottawa native was ordained a priest in 1965 for his home archdiocese and in 1987 was ordained auxiliary bishop of Sault Ste. Marie. He was appointed bishop on Dec. 2, 1989.
As a member of the Canadian Conference of Catholic Bishops, Plouffe has been a member of its permanent council (1991-95), served the Commission of Social Communications of the French Sector from 1993-97, chaired the Commission for Christian Unity, Religious Relations with Jews and Interfaith Dialogue (1999-2001), was on the Commission for Justice and Peace (2001-05), was Bishop ponens with the Knights of Columbus from 2005-07 and a member of the Standing Committee for Canon Law from 2011 to 2014.
Damphousse is a native of Saint-Joseph, Man., and was ordained a priest for the Saint-Boniface archdiocese in 1991. The 52-year-old has been bishop of Alexandria-Cornwall since Sept. 2, 2012.
The Diocese of Sault Ste. Marie has 96 parishes and missions with a Catholic population of 206,405 served by 76 diocesan priests, 12 priests from religious communities, 92 permanent deacons, 181 religious sisters and brothers and two lay pastoral assistants.