I found this link:  http://www.cic.gc.ca/english/information/applications/work.asp and from what I was reading, it is similar to the US in that they don't want to import people to take away jobs from citizens.  I am not sure where you would find information about volunteering but maybe if you found an agency that is taking volunteers, they would be able to help you.  We get Workamper News and rarely see many opportunities coming out of Canada.