Ichthy!

Had Greenlanders, like normal Norse, caught cod
they'd have occasion to give mighty thanks
to their new Christian Savior and God
for guiding their longships to the GrandBanks
the Portuguese fed Europe on salt fish
but only came ashore to dry their haul
no rival learned where they became so rich
until Columbus showed us where to trawl
Leif Erikson's odd dietary quirk
left North American for French and Brits
phlegmatic colonists, so not berserk
laid low the skaelings with disease and wits
strange petulance, a toddler's attitude
to starve where waters teemed with so much food