Again, and without being polite this time: BS. You don't know what you're talking about.
This is not "a worldwide understanding." Every American fly-fishing magazine refers to migratory Great Lakes rainbows as steelhead. Any number of American websites do the same. This usage is not in any way restricted to southern Ontario.
Some examples, since obviously you won't take my word for it.
The
Steelhead Site, based in Illinois and focusing on Great Lakes fishing:
https://steelheadsite.com/
University of Michigan site with lesson plan on Great Lakes
steelhead:
http://www.miseagrant.umich.edu/less...for-steelhead/
Michigan DNR page on
steelhead:
http://www.michigan.gov/dnr/0,1607,7...5692--,00.html
John Nagy, American
steelhead guide:
http://www.johnnagysteelheadguide.com/
Rio lines article on Great Lakes
steelhead:
http://www.rioproducts.com/blog/wint...ete-humphreys/
I'd suggest you take two and a half minutes to check into this. "Steelhead" for migratory rainbows is not southern Ontario slang. It's common usage throughout the Great Lakes region.
Whether or not the fish genuinely are "steelhead" is irrelevant, especially given that there is no genetic difference between an anadromous steelhead and a resident rainbow trout. You have said that only in southern Ontario are migratory rainbows called "steelhead." I have just proven you are full of it.
Is there anything left to say here?