I have seen them there thick in early may. heck they may be real thick right now???we seen most closer to the dam than we probaly should have been. we just happened upon them hunting them like bigheads. was reading a article about them in outdoor illinois that said they average 20 lb but the biggest they caught in a survey was 60lb. they look HUGE for there size. a 15 lb will look like it is 40 lb in the water