I caught a sunfish at the exact same spot, Thurs. the 23rd. Right at the mouth of the Kanaka where it meets the Fraser. I'd never seen one of them before and at first I thought, "WTF? Did someone release an aquarium fish in here?"
After putting the first fella back in the water, I realized that the little depression just 7 feet offshore that I was fishing in was literally loaded to the gills with the odd-looking little buggers. Was using a weight follwoed by 2 feet of leader and a barbless bait hook with a dew worm for bait. The sunfish robbed me blind of all my worms in under half an hour. If you're out for these guys, I'd suggest getting your worms threaded on as tight as you can.
As for Whonnock, i agree, it's sort of an unappetizing shoreline. Shares the sames characteristics as a few other lakes in the Maple Ridge area, namely: Mike Lake and Rolley. Creepy brown water, lots of lilly pads, mushy 'beach' and small fish... But your mileage may vary....