I expect we will learn that a well meaning volunteer placed the signs in the wrong place having less than a sufficient amount of training from the Park staff. My experience was the same as Jim's, but the nice volunteers asked for assistance from a very busy ranger who promptly produced a fishing regulations brochure. She then went back to assisting other volunteers desparately needing help clearing an elk jam. Seems, as she said with a smile, "a particular bull has taken to showing up at other than the agreed upon time of the day."
This brochure I got at the 2009 WNC Fly Fishing Expo from a nice young Native American minding the Cherokee Fish & Game Management booth.