How is collision avoidance regulated in controlled airspace in Canada?
You are correct, it applies when operating in the vicinity of an aerodrome:


  Division V — Operations at or in the Vicinity of an Aerodrome
  
  602.96 (1) This section applies to persons operating VFR or IFR aircraft at or in the vicinity of an uncontrolled or controlled aerodrome.
  
  (3) The pilot-in-command of an aircraft operating at or in the vicinity of an aerodrome shall
  
  
    (a) observe aerodrome traffic for the purpose of avoiding a collision;
  


Also this part:


  Part VI — General Operating and Flight Rules
  
  602.19 (1) Notwithstanding any other provision of this section,
  
  
    (a) the pilot-in-command of an aircraft that has the right of way shall, if there is any risk of collision, take such action as is necessary to avoid collision; and
    
    (b) where the pilot-in-command of an aircraft is aware that another aircraft is in an emergency situation, the pilot-in-command shall give way to that other aircraft.
  


The way I'd interpret the above is vigilance in see-and-avoid is always there, unless of course you don't have ACAS and TAWS and flying IFR in instrument meteorological conditions (IMC).