If you select to keep your old passport, Passport Canada will mail back your old passport separately to you (you will receive your new and old passports in two registered mails).
Visa is issued to a passport holder particularly for that passport. Commonly, you shall not use it with a new passport legally or technically. Also, the visa is linked with the original passport in computer system these days.
However, each visa issuer may have a "visa transferring service" available to simplify the process of applying a new visa. Good luck!