i didnt look at in in great detail with a magnifying glass but just looking at the pic i would say that it looks like it could possibly be the tail of a big old common snapper. this seems to be the most logical identification considering its in canada and the size of the creature is hard to tell. a scarred crocodilian tail does look possible too, that came to mind when i saw the pic. hopefully more pictures will be available to get a better idea of what it is.