I know what you're saying, but, theres a lot more fish than that being kept right now. I release about 90% of what I catch, I do keep the odd fish for a meal.
In all honesty though, there wouldn't be a daily limit on fish if the people in charge didn't think the fish population can survive it, I think they have better number than you or I could find. I don't know how many Canadians have a fishing license, or how many of those are C&R only or how many catch and keep. Neither do I know the number of people that poach fish, or fish without a license. All I know is that, with the exception of the Atlantic Salmon, our fishery is pretty good across Ontario.