Specifically looking for a species of catfish that can handle LONG winters, grows to decent sizes, and most importantly will breed readily to keep a self sustaining population?
The only two species that fit that bill would be the channel and blue catfish. I am not sure if they are even legal to stock in BC waters as neither species is native to the Pacific drainages. I would suggest you check with your governmental fisheries agency to see if they are first legal and second if either species can be sourced locally. If legal, but not available locally, you may be able to have some airmailed to you, but I suspect they'd be quite pricey and many hatcheries will not ship catfish because their dorsal and pectoral fins have very sharp spines that can puncture the shipping bags.
