The vast majority of unionized postdoctoral fellows in Quebec are members of the Public Service Alliance of Canada (PSAC), except those from UQAR.
If you are from UQAR, be aware that the section Union network, from local to national is addressed mainly to PSAC members. Note also that the sections How does a local union operate? and Drawing up a collective agreement may not accurately correspond to the practices of your union.
For information on your union, see SCFP 1575