That varies province to province.
In Nova Scotia:
No person may be
prosecuted for contravening any notice given
pursuant to this Act prohibiting entry or prohibiting
activity on "forest land" as defined in the Act if that
person is hunting as defined in the Wildlife Act,
fishing, picnicking, camping, hiking skiing or
engaged in another recreational activity or
engaged in the study of flora or fauna.
"forest land" means a wooded area, forest stand,
tract covered by underbrush, barren ground, marsh
or bog.
"hunting" means chasing, driving, flushing,
attraction, pursuing, worrying, following after or on
the trail of, searching for, trapping, attempting to
trap, snaring or attempting to snare, shooting at,
stalking or lying in wait for any wildlife whether or
not the wildlife is then or subsequently captured,
killed, taken or wounded, but does not include
stalking, attracting, searching for or lying in wait for
any wildlife by an unarmed person solely for the
purpose of watching or taking picture of it.
I've run into a similar issue back home recently. When they get into trouble is building a blind, leaving garbage, causing damage, or violating hunting regs.
WRT hunters; Basically once they break a law they are deemed to no longer be engaged in a lawful activity under the wildlife act and are then subject to trespass charges.