Funny how I manage to figure something new out every time I read the fishing regulations guide. I noticed that in the Montreal area (zones 7 & 8), we are allowed to use 10 lines between December 20th and March 31st.
I imagine they were thinking of ice fishing when they put this rule in place, but because of the wording, it turns out that we can fish open water with up to 10 lines per person. I confirmed this with a conservation officer just to make sure before I posted this, I wouldn't want anyone getting into trouble because of something they read here.
I doubt anyone can handle 10 lines in open water on their own, maybe 3. But it leads to some wild ideas. Imagine hitting some schooling fish, or heading out with a bunch of friends at once. It would likely make a very interesting Youtube clip.
If you do intend to take advatange of the multiple lines allowance, I suggest printing that section of the regulations, just in case you bump into some uneducated / overzealous anglers or conservation officers.