Stuart Molson became interested in Atlantic salmon conservation as a founding member of the Atlantic Salmon Association (ASA) in 1948 and served as the association's Secretary-Treasurer from 1949 to 1970. It was through his efforts that the funds were found to establish the association and to launch it as the first salmon conservation organization in Canada. He was elected Honourary Chairman in 1973, a post he held until his death in 1983.

Stuart started fishing in the 1920s and for the rest of his life he looked with great anticipation to the month that he devoted each year to salmon angling on the Godbout River in Québec.

Although Stuart Molson was actively involved in many Atlantic salmon conservation efforts, he preferred to work in the background, keeping his involvement low-profile, while allowing others to receive the credit and publicity he thought they deserved.