I fish the Croix for muskies and smallies, also. Every time I go I see sturgeon from 30 inches jump to sturgeon that are 60-70 inches. Maybe 20 jump a day? I’ve caught a 57″ down there. My friend has got a 60 1/2. I am guessing you were fishing close to the st croix bridge? Sunds awesome! If you want to catch some sturgeon head out to the Taylors Falls dam and cast out a worm and a sinker. Geat fish and tight lines!!