North-west coast dwellers in the Americas did very well with fishing and whaling, some eked this out with raiding, piracy and slaving. Believe they had sort of garden plots as well. So obviously one could manage there just as one could crofting up the seabords of Britain and Ireland. Foraging in either UK or Canada could lead to slim pickings until into the Mesolithic routine IF very few people were doing so it would be viable.
Again, I think the example shows large scale communal living and distribution of resources, not one person with a .308 rifle and a fishing rod. They are very different realities. A person alone could do it in certain locations during certain times of year, but I have not seen any examples, historical or current where that has been done in a self sustaining long term manner. Not to mention having to do so without modern hunting and fishing gear. Hunting with the Bow and Arrow by Saxton Pope has a good account of a Native American who was found living alone after his tribe was killed/died out: http://woodtrekker.blogspot.com/2010/07/hunting-with-bow-and-arrow-by-saxton.html