I haven't seen many lamprey in the cold water fisheries, but we see quite a few in the warmer water streams. Not too many on game fish, but I have seen many on Buffalo fish in taken while gigging in the lower stretches of the Meramec river.
Dern things come of the fish in the bottom of the boat and crawl into every crevice in the boat. You won't know thier there for a day or two. Then when the sun come out and warms things up, just follow your nose.