Tunnel Mtn, Banff Bear Warning

I know Canada hates American guns, but bears are no fun. We are leaving for Banff this weekend. Should I bring a shotgun? I have rubber buckshot and rubber slugs to be used to drive off bears. They can get pesky where we live. What trouble will I have at customs? We've not tried to bring guns in in the past.

Also going to Lake Louise and Jasper if that makes a difference.