This study was actually performed for two years. In the first year, which is the one I have references for, tests were done in a region where there were basically very few, if any, active farms. The permanence of the fish in that area was very short. I don't have the final data for the second year, but the permanence was definitely longer once the farms were actually present.
Evidence of meeting #22 for Fisheries and Oceans in the 43rd Parliament, 2nd session. (The original version is on Parliament’s site, as are the minutes.) The winning word was wild.
A video is available from Parliament.