Born in Verner, in Northeastern Ontario, Poitras was mostly known for his involvement in the co-operative movement in his region. In 1945, he joined the group of seven that was committed to study the social doctrine of the Church witch fostered mutual aid and co-operation. Under the leadership of Reverend Oscar Racette, the group obtained, in 1945, the Foundation Charter of the Caisse populaire de Verner, in which Poitras served as the first manager. That year, he opened in his house a farm product sales counter for the Union catholique des cultivateurs franco-ontariens. In1946, he was granted by the provincial government the right to open the credit union in his house, and his sales counter was replaced by a co-operative counter. Deeply involved in his community, he was a pioneer in the construction of a co-operative flour mill in 1948 in order to meet the needs of farmers. A milk transportation service was added to it in 1960. The fact that the Coopérative régionale de Verner was regarded as one of the main drivers of the co-operative movement in the Nipissing District is largely due to Marius Poitras’ dedication.