I grew up used to the notion that the season for pike and walleye always opened the Saturday one week before the long weekend, though I believe that it's since been pushed back to the "May 24" weekend in many areas so do read the regs! Similarly, there used to be lots of popular spots to fish for spawning and post spawn walleye below many locks and dams that have in many cases been turned into fish sanctuaries for a couple of weeks longer than the opening day everywhere else, so if you hear of such a spot, do make sure that you research it before driving out two hours just to come across a No Fishing sign.
Great lakes tributaries get runs of steelhead in the spring with open seasons on select stretches of rivers before the opener at the end of April. There's usually a few fish remaining for the first week or two of May, especially if the weather's been cooler and there's been sufficient rain to bring the fish farther upstream than normal. Even in the Toronto area alone, there's considerable stretches of the Credit, Humber, Rouge and Duffins Creek that hold trout (sometimes surprisingly overlooked by the anglers travelling further to fish), though you might find the rivers flowing into Georgian Bay like the Bighead or Beaver more of an adventure.
Warm water options will in large part depend upon whether the season for walleye and pike are open on the weekend in question. If they are, it will be more of an issue of narrowing down your options and deciding whether or not you'll rent a boat, acquire/borrow a canoe or find places where you can fish from shore. If you could find a place on shore from which to catch Lake Simcoe perch at that time of year I'll be most envious! Perhaps one really neat mixed bag option would be to fish the provincial park on the Nottawasaga River near Wasaga beach, to which one of my highschool teachers brought a busload of us from Toronto many years ago on a May afternoon after school. I caught a tiny pike, a few rock bass and smallmouth (still out of season) plus a huge redhorse sucker, while others caught a mixture of fish and one girl in our group managed to land a decent size carp. There were probably walleye still in the river, the odd drop back steelhead and I'm trying to remember if anyone caught channel catfish. We had our luck with good old fashioned worms and for several of my fish, a Mepps spinner.
There are many other options. Some stretches of the Grand River should hold some interesting selections of fish, including Pike around Belwood Lake and I've also seen all sorts of fish caught below a dam on the Trent Canal (River?) in Trenton, though it could get crowded with fishermen from the city. One of these days I'm promising myself to take my float tube on the ferry to Toronto's Centre Island to try for the mixed bag of pike, bass and other fish that roam there, just a streetcar ride from where I live. That same highschool teacher that I referred to earlier had the head mounted of a nineteen pound pike that he caught there when he was a boy. I've even managed to catch salmon on two occasions casting from shore in one of Toronto's waterfront parks, so you'd be surprised where you could find fish!
Years ago there also used to be really nice runs of White Bass in many Great Lakes tributaries in May, including the Niagara, which allowed for catching large numbers of sub-one pound fish on light tackle and spinners. Sadly however, I believe that their populations in Lake Ontario have crashed in recent years due to changing environmental conditions, but if someone knows otherwise and can pipe up, that would be another interesting option.
If you have any further questions on these or other possiblities do continue asking. I'd be more than happy to oblige, even if I might decide to PM you the more detailed locations.
Regards,
Frank
