After finishing with sturgeon for the day, I checked out some back bays. Weed growth is looking good, and temps were as high as 63 degrees in the isolated protected bays. I would expect you to find a mixed bag of spawning and post-spawn fish on the opener. One area of the lake (river) that is less isolated from the main water's temperature influence may be cool enough to still have spawning fish, but isolated areas protected from current and wind will probably be post-spawn already. I wouldn't be worried about any pre-spawn fish so things should start off on a good note!

I fish sturgeon on the Manitoba side of the Winnipeg River, but there are still some kicking around on the Ontario side. The MNR was doing a netting study on sturgeon a couple years ago around Minaki and only netted one sturgeon during their entire study... but it was 8 feet long... probably worth at least tossing in a line if you have nothing else to do, haha.