The settlements were not in danger of going hungry but possibly the walrus harvest began to falter and without those walrus tusks and blusik sticks, what was a Scottish or Norwegian warrior/nobleman to do? He certainly wouldn't be giving his silver or gold to the Greenlanders eh!
One problem with a diet high in seal, huskey or polar bear is the toxicity of the liver ~ too much vitamin A can make you sick ~ and entirely too much can kill you. This was supposedly understood by the Inuit (Greenland and Canada's Eskimo are lumped under one tribal name, however proper that is I have no idea) and one can imagine the Sa'ami must have known about it, and the Norse as well ~ after a couple of years of eating seal.
Reindeer, that ever popular subarctic deer also have a high iron content, as do the seals ~ so anemia was probably not a problem for anyone in the North ~ on the other hand, too much iron is a problem for most everybody without some sort of porphyria to get rid of the surplus. Iron deposits in the skin would have been common with this crowd ~ might even have looked rather metalic.
Not to mention perpetually constipated.
You wrote:
“They call them Norse, but no doubt a number of them were Sa’ami...”
No, not a single one of them. They WERE Norse. None of them were Lapps. Not a single one.
Your Lapp obsession makes you see things that are not there. Get help.
“Reindeer, that ever popular subarctic deer...”
I recomember that reindeer/caribou meat lacks a fatty acid that is essential to humans. Same with rabbits. In other words, humans cannot live on a diet consisting solely of Santa’s helpers or bunnies or they will slowly but surely starve to death.
If their diet consists of majority seal meat I suspect that their body odor would be so strong that they would stop having intimate relations ergo the population would die out...