Can't tell exactly from the picture but they look like male Redside shiners to me. They do pretty well in cold water and high elevation lakes.
From the 3rd edition of "How to Know the Freshwater Fishes" by Samuel Eddy and James C. Underhill page 82:
"Redside Shiner Richardsonius balteatus (Richardson) Dark above with silvery sides and belly, rosy in breeding males; 9-11 dorsal rays; anal rays more than 10 (16+)... Length up to 6 inches. [Native to] Colombia River drainage and Salt Lake Basin."
I know that in Scofield Reservoir in Utah these have been introduced either by bait bucket or "bucket biologists"--illegally either way. I was there last weekend and the shiners were THICK! They compete with young trout for food and are known to eat trout eggs and fry. Larger trout will feed on them, but they're next to impossible to get rid of without poisoning the whole lake.
Utah has a chub problem in some lakes too. Strawberry has Utah chubs over a pound that get caught pretty regularly by trout fishermen, but the hope is that the high number of large cutthroats will keep them in check.
They look similar to a Red belly dace but at 6" these are twice as long as the largest dace.
Out of curiosity, what kind of predatory fish are in Pearl Lake?
Yep they are some sort of sucker found on the western slope higher up lakes they get a really pretty reds stripe down there sides during spawning and at least in my experience dont get much bigger then around 8" in those lakes at least here is more info on them http://www.fishbase.org/Summary/SpeciesSummary.php?id=2962