LYNN – Monsignor Paul V. Garrity has launched a transition process aimed at taking him out of St. Mary’s parish and introducing a successor priest, hopefully by June.Garrity stunned parishioners Sunday announcing plans for his departure during St. Mary’s 9 a.m. Mass.”I am leaving,” he said, before outlining a departure process mirroring the one he outlined in the parish bulletin.In his “pastor’s desk” message to parishioners, Garrity explained that pastors are appointed by the Archdiocese of Boston to six-year parish terms. Many priests serve two terms but, wrote Garrity, ones serving beyond 12 years can expect reassignment on short notice.Garrity told parishioners he has decided to be pro-active about his possible reassignment and the Archdiocese’s selection of his successor.”I am hoping that a successor can be identified who could overlap my term, learn about St. Mary’s and continue the spirit of welcome and vitality that characterizes our community today,” he wrote.Attempts to reach Archdiocese spokesman Terrence Donilon Monday for comments about the transition process were unsuccessful.According to zoominfo.com, Garrity grew up in Somerville. He graduated from St. Clement’s High School in Somerville in 1965 and St. John’s College in 1969. In 1973 he received a Master of Divinity Degree from St. John’s School of Theology and a Master of Arts Degree in Political Science from Boston College in 1974.Garrity’s news caught parishioner Patricia Gill by surprise.”I was shocked. His contribution has been outstanding. He’s kept St. Mary’s a strong community,” Gill said.Garrity was a University of Massachusetts Lowell campus chaplain in 1992 when the Archdiocese offered him the choice of continuing campus ministry or go to St. Mary’s parish in the center of Lynn.He chose Lynn and took on the challenge of leading a parish with a school facing financial challenges.”Paul Garrity brought our alumni together and provided a vision,” said St. Mary’s High School Principal Carl DiMaiti.Over the next two decades, Garrity led efforts to stabilize the school, welcomed Haitian, Congolese and other immigrants into the parish and helped lead fund-raiser efforts to build the (William) Connell media center in 2004.He also helped map out the former St. Jean’s Church transition from vacant buildings into housing on Franklin and Endicott streets and oversaw the former convent’s renovation into St. Theresa House, a senior residence.”Paul Garrity has done great things for the church and the Greater Lynn community,” DiMaiti said.”I have no doubt the Archdiocese will hand him a great challenge.”