Last year I was fishing for chubs and I sometimes noticed larger fish slamming my float from time to time. It always happened just as the sun was going down so I guess they are more bold at that time of day. It must be these Pike Minnows if they get so big . Next time that happens I might even try to put a dry fly out - just to see what happens.
Some of these larger fish slamming on the surface are definitely northern pikeminnow, but depending on the time of the year, they are very likely to be large bull trout. Heading down to North, Middle and South Arms in June, you'll often see these large boils on the surface during an outgoing tide. They're feeding on outmigrating salmon smolts, eulachons and whatever small minnows they can find.
Usually the water clarity isn't great in June because of freshet, but somehow we have had outings when we would connect with a dozen bull trout on lures. The water visibility would only be around 6 inches, but the vibration on the spinner has done the trick so far.