European fishing operations are alleged to have operated on both sides of the North Atlantic in pre-Columbian times.
According to some well known maritime historians such journeys were possible even in the Early Middle Ages. However, the North Atlantic storm cycles, which include spent hurricanes from the South, really didn't allow them much time for such trips.
The development of the Spanish Caravel overcame those limits and, surprise, surprise, Christopher Columbus made a trip just about as soon as anyone could do so.
One noteworthy item is that harp seal hunters discovered Labrador in the 1500s, cleaned the place out, and by the early 1600s there were vast stores of codfish in the Grand Banks and Georges Banks.
Recently the Canadians have reversed their policy on harpseals with the hope of restoring the codfish. (NOTE: harpseals prefer to eat cod at their prime breeding age.)