Kokanee tactics are very different here and there. In northern Cali, the common method is downrigging as the Kokes can be up to 250' deep. In the Northwest, jigging is the norm, but downrigging is gaining popularity. When I tell Koke fishermen on the west coast that we can catch Kokes nearly anytime of year on the subsurface, they freak. Water tempature is key to salmon fishing as it is for many species, the fact that early ice off is when they are jumping in Oregon is the water temp (of course).
As to your question of the schools here in Colorado, yes you can still jig for them in open water, you just don't cover much water, thus you lower your odds of finding the fish. It's interesting how techniques vary according to region. Learning different methods can sometimes really pay off.
id troll , jigging is a good method also , but kokanee are moblie fish , they are always on the move following the plankton , so if you stop to jig they might come threw once then you wont see them again , trolling covers alot of water and your odds of catching them will increase
look for them "dimpling the surface when its dead calm in the morning. them throw spoon in their direction and use a stop and go retreive. we get them till about 1100 in the am or until the wind kicks up and we cannot find them. do not let your boat get to close they will spook down. bernie