there is good reason to believe that illiterate British and Breton fishermen had already discovered the banks of Newfoundland and had kept the discovery secret to their own advantage.
I have a book called Cod(and I'm damned if I can remember the author right now) which devotes a chapter to making this case--the quantity of fish that Breton and Portuguese ships were coming back with pretty much had to have come from the Grand Banks/Georges Bank (which is coincidentally also where The Perfect Storm takes place).