With gobies around, I do not think temp is as much of a variable now as it used to be. Warmer temp pockets usually hold more fish. Browns will be found in cooler water if food is there. My buddy took 2 browns in 50 fow yesterday glued to the bottom. The water was 44 degrees on the bottom. The water inside along shore was warmer but void of browns. Once the thermalcline sets up, browns can be found where the thermalcline intersects the bottom and warmer (most of the time inside the intersection of the thermalcline and the bottom). Riggers, wire divers, leadcore, coppers and plainerboards with drop weights will all work. As for a temp where browns vacate the shallows, there are many variables that change that. Most of the time the browns start to move out when the water hits upper 50's and low 60's.