I've got a Pakistani passport and a valid student visa for England. I'm going to travel to the Dominican Republic with a stay of 17 hours at a Canadian airport. Do I need a transit visa?
According to this nifty tool provided by the Canadian authorities, it seems that Pakistani nationals need a visa if visiting or transiting Canada:
You need a visa to visit or transit Canada.
Starting December 11, 2013: citizens of your country will need to provide biometrics (fingerprints and photograph) when applying for a visa. Learn more about biometrics.