I'm aware of that (and that definitely fuels the majority of the politics of this diaspora) there is a large number that came over pre-USSR times as it was essentially advertised to them to come over and 'settle the west'.
Edit: What I think I mean to say is that a lot of 'Ukrainian Identity' in Canada comes from being descendants of those that arrived in the 'first-wave' section from here https://en.wikipedia.org/wiki/Ukrainian_Canadians. Which is kind of interesting because for lots of these people their last connection to the actual land of Ukraine was from over a century ago now.