During the winters of 1959 to 1962, 2459 commercial-sized cod were tagged off the Canadian coast south of the Laurentian Channel. Most returns came from the same general area. Very few cod crossed the Laurentian Channel to Newfoundland or Gulf of St. Lawrence North Shore grounds, or the Scotian Gulf to grounds off western Nova Scotia. Several cod populations were observed, each moving south in autumn and north in spring months. Fish tagged off central Nova Scotia did not migrate as far as the Gulf of St. Lawrence, but those tagged off Cape Breton migrated into the southwestern Gulf for summer months. Fish marked in the middle of the area were intermediate in their migration pattern. Temperature and feeding appear to be the important factors associated with cod migrations. Cod remain in temperatures of 1 degree to 4 degree C during winter months by moving to deeper water. In spring, cod disperse and feed in shoaler water. The cod of the Western-Emerald Banks area move east over the Scotian Shelf. The Gulf cod move up through the cold-water layer and north to inshore feeding near the Magdalen Islands and the Gaspe peninsula.