Please note that all passengers travelling to Canada and connecting onto a domestic flight need to clear their baggage through customs at the first airport of entry in Canada and hand it over to the transfer desk. This requirement is mandatory, even if the baggage has been tagged with its final destination in Canada.
eTA (Electronic Travel Authorization)
As from 15 March 2016 visa-exempt foreign nationals who fly to or transit through Canada will need an Electronic Travel Authorization (eTA). Exceptions include U.S. citizens and travellers with a valid visa. If you are planning to transit in Canada or intend to stopover on the way to your destination, you will still need to apply for an eTA.
Please note that if you transit through or stopover in Canada to travel to the US (or viceversa), you will need both an eTA and an ESTA (Electronic System for Travel authorization for the US).