I know this is a late post, however, I am from the Burlington/Oakville area and have fished Bronte before. From what I understand the only places you can't fish are the various sanctuaries like Lowville and Bronte Creek P.P, and a few other spots up around the Freelton area during spawning the season and they all have No-Fishing signs posted.
For fishing in posted no-fishing zones - nothing is stopping you other than your morals and the odd MNR officer lol, but we need to be responsible about our resources. I know this probably isn't what you meant, but still worth noting I think lol.
Also from what I understand a landowner cannot kick you off Bronte in a canoe, unless you are fishing from shore or wadding from shore on their property posted with signs and without permission. Again I know its late, but I have a couple friends who work at Bronte If you are still interested, I can see if they can dig up some documents on land and water rights on the river. Another place to go to check out this information would be the Centre for Inland waters by the lift bridge on theBurlington side off Birdgeport!