To my knowledge, the maintenance of economic services is not considered as the maintenance of essential services under any of the labour codes.
Again, the Canada Labour Code states: (2) An employer or a trade union may, no later than 15 days after notice to bargain collectively has been given, give notice to the other parties specifying the supply of services, operation of facilities or production of goods that, in its opinion, must be continued in the event of a strike or a lockout in order to comply with subsection (1) and the approximate number of employees in the bargaining unit that, in its opinion, would be required for that purpose.
It then talks about how to notify the other party in order to determine essential services. It also addresses the agreement between the parties, its wording and its filing with the CIRB.
Lastly, here's what it says about cases in which there is no agreement: [...] the Board shall, on application made by either party no later than 15 days after notice of dispute has been given, determine any question with respect to the application of subsection (1).
Is that in fact what you do?