The rivers are filled with fishies! As Dean mentioned above, the head of the
St Clair is sheer awesome for sturgeon in June / early July and large schools of pickerel about year round.
Another great river often overlooked by divers is the
upper Niagara (well before the falls). Fish abound throughout the river including spotting of muskies, occasionally / rarely a sturgeon, but lots of bass, carp, sheepshead, pickerel and in the spring large schools of killer minnows (if night diving!). A great spot is "Thompson's Hole", google it. It's a divot in the river, a swirling massive whirlpool, with large fish including muskies lingering around it's 60' depth. (the rest of the river is typically 25-30' at it's deepest). Another amazing spot on the Niagara is mid way across the river just upstream of the railroad bridge (watch that US border! or vice versa). There are quiet oases (no current) spots, where large fish comically congregate in 35' depths.. it's really quite magical.
The whole
St Lawrence River is of great scaly wonder, especially in the 1000 islands. One of my favorite temporal spots is catching the spawning channel cats at around the 40' mark in late June / early July at Ivy Lea campgrounds. (you can day dive there for a small fee). Channel Catfish are so amazingly ugly that they are utterly beautiful in their uniqueness and grace underwater, in my opinion
. They are protecting their nests so please don't harrass them! Watch from a distance, they may even come check you out if you are unobtrusive in your approach.
J.>